Microbial biopesticides for invertebrate pests and their markets in the United States

Strategic Analysis of Collaborative Networks in Spodoptera frugiperda (Lepidoptera: Noctuidae) Research for Improved Pest Management Strategies

The fall armyworm (FAW) poses a significant global threat to food security, and economics. Timely detection is crucial, and this research explores innovative techniques like data analysis, remote sensing, satellite imagery, and AI with machine learning algorithms for predicting and managing outbreaks. Emphasizing the importance of community engagement and international collaboration, social network analysis (SNA) is employed to uncover collaborative networks in FAW management research. The study analyzes a decade of research, revealing trends, influential institutions, authors, and countries, providing insights for efficient FAW management strategies. The research highlights a growing interest in Spodoptera frugiperda (Smith and Abbott 1797) research, focusing on biological control, chemical insecticides, plant extracts, and pest resistance. Co-Citation analysis identifies key research concepts, while collaboration analysis emphasizes the contributions of actors and institutions, such as China, the USA, and Brazil, with international collaboration playing a vital role. Current research trends involve evolving resistance, insecticidal protein gene discovery, and bio-control investigations. Leveraging insights from collaborative networks is essential for formulating effective strategies to manage fall armyworm and ensure global food security. This comprehensive analysis serves as a valuable resource for researchers and stakeholders, guiding efforts to combat this pervasive agricultural pest.

Complex nitrogen sources from agro-industrial byproducts: impact on production, multi-stress tolerance, virulence, and quality of Beauveria bassiana blastospores

We investigated the impact of various complex organic nitrogen sources on the submerged liquid fermentation of Beauveria bassiana, a versatile entomopathogenic fungus known for producing hydrophilic yeast-like single cells called blastospores. Specifically, we examined yeast extract, autolyzed yeast, inactive yeast, cottonseed flour, corn bran, and corn gluten meal as nitrogen compounds with different carbon-to-nitrogen (C:N) ratios. Our comprehensive analysis encompassed blastospore production, tolerance to abiotic stresses, shelf stability after drying, and virulence against mealworm larvae, crucial attributes for developing effective blastospore-based biopesticides. Notably, cottonseed flour emerged as the optimal nitrogen source, yielding up to 2.5 × 109 blastospores/mL within 3 days in a bioreactor. These blastospores exhibited the highest tolerance to heat stress and UV-B radiation exposure. The endogenous C:N ratio in blastospore composition was also impacted by nitrogen sources. Bioassays with mealworm larvae demonstrated that blastospores from cottonseed flour were the most virulent, achieving faster lethality (lower LT50) and requiring a lower inoculum (LC50). Importantly, blastospores produced with cottonseed flour displayed extended viability during storage, surpassing the retention of viability compared to those from autolyzed yeast over 180 days at 4°C. Despite differences in storage viability, both nitrogen sources conferred similar long-term blastospore bioactivity against mealworms. In summary, this research advances our understanding of the crucial impact of complex organic nitrogen selection on the phenotypic traits of blastospores in association with their intracellular C:N ratio, contributing to the production of ecologically fit, shelf-stable, and virulent propagules for effective pest biocontrol programs.

IMPORTANCE

Biological control through entomopathogenic fungi provides essential ecological services in the integrated management of agricultural pests. In the context of submerged liquid fermentation, the nutritional composition significantly influences the ecological fitness, virulence and quality of these fungi. This study specifically explores the impact of various complex organic nitrogen sources derived from agro-industrial byproducts on the submerged liquid fermentation of Beauveria bassiana, a versatile entomopathogenic fungus known for producing hydrophilic yeast-like blastospores. Notably, manipulating the nitrogen source during submerged cultivation can influence the quality, fitness, and performance of blastospores. This research identifies cottonseed flour as the optimal low-cost nitrogen source, contributing to increased production yields, enhanced multi-stress tolerance, heightened virulence with extended shelf life and long-term bioactivity. These findings deepen our understanding of the critical role of nitrogen compound selection in liquid media formulation, facilitating the production of ecologically fit and virulent blastospores for more effective pest biocontrol programs.

Emulsifiable oil-formulated Beauveria bassiana competes with imidacloprid for seasonal control of cereal aphids in Zhejiang, China

BACKGROUND

Alternatives to neonicotinoids against cereal aphids are needed to mitigate aphid resistance and non-target effects. The emulsifiable oil formulations of two Beauveria bassiana strains, namely Bb registered as a mycoinsecticide and TBb overexpressing an endogenous virulence factor, were tested for seasonal control of cereal aphids at the elongating (April 7) to milk ripening (May 12) stages of winter wheat crop in Yuhang, Zhejiang. Each of three field trials consisted of blank control and the treatments (three randomized 100-m2 plots per capita) of each fungal strain sprayed biweekly at rates of 1.0 × 1013 and 1.5 × 1013 conidia ha-1 and 10% imidacloprid WP sprayed biweekly at a label rate.

RESULTS

Tiller infestation percentage and aphid density in the 5-week field trials after the first spray were reduced to 18.7-22.4% and 9.1-12.4 aphids per tiller in the fungal treatments, and 12.8-25.3% and 2.8-20.9 aphids per tiller in the chemical treatment, contrasting with 49.2-60.3% and 37.1-108.5 aphids per tiller in the control. Percent control efficacies (±SD) computed with weekly aphid densities over the period averaged 84.0 ± 1.6 and 85.3 ± 1.8 versus 78.0 ± 4.0 and 79.9 ± 3.2 in the high-rate versus low-rate treatments of Bb and TBb, respectively, and 84.5 ± 7.8 in the chemical treatment. Imidacloprid showed faster kill action but more variable efficacy than the fungal treatments throughout the trials.

CONCLUSION

Either Bb or TBb formulation competes with imidacloprid in reducing percent infestation and aphid density. The overall efficacy was significantly higher in the treatments of TBb than of Bb. © 2024 Society of Chemical Industry.

Factor-Dependent Internal Ribosome Entry Site and -1 Programmed Frameshifting Signal in the Bemisia-Associated Dicistrovirus 2

The dicistrovirus intergenic (IGR) IRES uses the most streamlined translation initiation mechanism: the IRES recruits ribosomes directly without using protein factors and initiates translation from a non-AUG codon. Several subtypes of dicistroviruses IRES have been identified; typically, the IRESs adopt two -to three overlapping pseudoknots with key stem-loop and unpaired regions that interact with specific domains of the ribosomal 40S and 60S subunits to direct translation. We previously predicted an atypical IGR IRES structure and a potential -1 programmed frameshift (-1 FS) signal within the genome of the whitefly Bemisia-associated dicistrovirus 2 (BaDV-2). Here, using bicistronic reporters, we demonstrate that the predicted BaDV-2 -1 FS signal can drive -1 frameshifting in vitro via a slippery sequence and a downstream stem-loop structure that would direct the translation of the viral RNA-dependent RNA polymerase. Moreover, the predicted BaDV-2 IGR can support IRES translation in vitro but does so through a mechanism that is not typical of known factorless dicistrovirus IGR IRES mechanisms. Using deletion and mutational analyses, the BaDV-2 IGR IRES is mapped within a 140-nucleotide element and initiates translation from an AUG codon. Moreover, the IRES does not bind directly to purified ribosomes and is sensitive to eIF2 and eIF4A inhibitors NSC1198983 and hippuristanol, respectively, indicating an IRES-mediated factor-dependent mechanism. Biophysical characterization suggests the BaDV-2 IGR IRES contains several stem-loops; however, mutational analysis suggests a model whereby the IRES is unstructured or adopts distinct conformations for translation initiation. In summary, we have provided evidence of the first -1 FS frameshifting signal and a novel factor-dependent IRES mechanism in this dicistrovirus family, thus highlighting the diversity of viral RNA-structure strategies to direct viral protein synthesis.

Rad6, a ubiquitin conjugator required for insect-pathogenic lifestyle, UV damage repair, and genomic expression of Beauveria bassiana

The E2 ubiquitin conjugator Rad6 is required for DNA damage bypass in budding yeast but remain functionally unknown in filamentous fungi. Here, we report pleiotropic effect of Rad6 ortholog in Beauveria bassiana, a wide-spectrum fungal insecticide. Global ubiquitination signal was greatly attenuated in the absence of rad6. The blocked ubiquitination led to severe growth defect, blocked asexual development, and abolished infectivity/insect pathogenicity, which correlated with compromised conidial quality (including viability, hydrophobicity, adherence to insect cuticle, and thermotolerance) and blocked secretion of cuticle-degrading enzymes including Pr1 family proteases. Importantly, Rad6 played much greater role in photoreactivation of UVB-impaired conidia by a 3- or 5-h light plus 9- or 7-h dark incubation than in dark reactivation of those impaired conidia by a 12-h dark incubation. The high activity of Rad6 in photoreactivation in vivo was derived from its link to a protein complex cored by the photolyase regulators WC1 and WC2 via the strong interactions of Rad6 with the E3 partner Rad18 and Rad18 with WC2 revealed in yeast two-hybrid assays. Transcriptomic analysis resulted in identification of 2700 differentially regulated genes involved in various function categories and metabolism pathways, indicating a regulatory role of Rad6-mediated ubiquitination in gene expression networks and genomic stability. Conclusively, Rad6 is required for asexual and insect-pathogenic lifecycles, solar UV damage repair, and genomic expression of B. bassiana. The primary dependence of its strong anti-UV role on photoreactivation in vivo unveils a scenario distinct from the core role of its yeast ortholog in DNA damage bypass.

Microbial Biofungicides as a Substitute for Chemical Fungicides in the Control of Phytopathogens: Current Perspectives and Research Directions

These days, two important issues are causing concern in the global community: the alarmingly growing trend of the human population and the issue of food security. To this end, people around the world have been searching for solutions that could feed the needy in a sustainable way. In response to this urgent call, scientists from around the world started working on increasing crop production and productivity by controlling crop pathogens that could harm the productivity of crops. Synthetic fungicides have been in use for controlling crop diseases for several decades, but later, due to the evidenced side effects of the fungicides, there have been attempts to shift towards a less cost-effective and eco-friendly method of controlling crop diseases, and so far, many remarkable results have been achieved. However, due to the less effective and shorter shelf life of microbial biofungicides, as well as the less accessibility of these microbial biofungicides to growers around the world, it became difficult to remove the fungicides totally from the market. To minimize this problem, researchers suggested an integrated approach: the combination of microbial biofungicides with a reduced dose of synthetic fungicides. Hence, this review explored the status as well as the merits and demerits of microbial biofungicides as compared to synthetic fungicides.

Toward an Integrated Understanding of the Lepidoptera Microbiome

Research over the past 30 years has led to a widespread acceptance that insects establish widespread and diverse associations with microorganisms. More recently, microbiome research has been accelerating in lepidopteran systems, leading to a greater understanding of both endosymbiont and gut microorganisms and how they contribute to integral aspects of the host. Lepidoptera are associated with a robust assemblage of microorganisms, some of which may be stable and routinely detected in larval and adult hosts, while others are ephemeral and transient. Certain microorganisms that populate Lepidoptera can contribute significantly to the hosts' performance and fitness, while others are inconsequential. We emphasize the context-dependent nature of the interactions between players. While our review discusses the contemporary literature, there are major avenues yet to be explored to determine both the fundamental aspects of host-microbe interactions and potential applications for the lepidopteran microbiome; we describe these avenues after our synthesis.

Effect of fluorescent brighteners on the insecticidal activity of Bacillus thuringiensis var. kurstaki and LdMNPV on Lymantria dispar asiatica in Korea

Stilbene-based fluorescent brighteners (FBs) have been demonstrated to improve the insecticidal activities of entomopathogenic viruses; however, there is limited information regarding their effect on entomopathogenic bacteria. We conducted this study to investigate the effect of two FBs (FB 28 and FB 71) on the insecticidal activities of Bacillus thuringiensis var. kurstaki (Btk) and Lymantria dispar multiple nuclear polyhedrosis virus (LdMNPV) on Lymantria dispar asiatica. FB 28 and Btk combination at low concentration (1.6 × 102  IU/mL) increased the mortality, whereas FB 71 and Btk combination at intermediate and high concentrations (1.6 × 103 and 1.6 × 104  IU/mL) slightly reduced the mortality compared with that with Btk alone. The lethal time was also shorter with combinations of Btk and FB 28 than with FB 71. Both FB 28 and FB 71 increased the mortality in combination with LdMNPV at all concentrations (3 × 102 , 3 × 104 , and 3 × 106  polyhedral occlusion bodies/mL compared with that with LdMNPV alone. Our results suggest that FBs improve the insecticidal activities of Btk and LdMNPV, and their activities depend on their interactions with the midgut structures of the host insect species.

Greater wax moth control in apiaries can be improved by combining Bacillus thuringiensis and entrapments

The greater wax moth (GWM), Galleria mellonella (Lepidoptera: Pyralidae), is a major bee pest that causes significant damage to beehives and results in economic losses. Bacillus thuringiensis (Bt) appears as a potential sustainable solution to control this pest. Here, we develop a novel Bt strain (designated BiotGm) that exhibits insecticidal activity against GWM larvae with a LC50 value lower than 2 μg/g, and low toxicity levels to honey bee with a LC50 = 20598.78 μg/mL for larvae and no observed adverse effect concentration = 100 μg/mL for adults. We design an entrapment method consisting of a lure for GWM larvae, BiotGm, and a trapping device that prevents bees from contacting the lure. We find that this method reduces the population of GWM larvae in both laboratory and field trials. Overall, these results provide a promising direction for the application of Bt-based biological control of GWM in beehives, although further optimization remain necessary.

Biological control of Cimex lectularius with Beauveria bassiana: Effects of substrate, dosage, application strategy, and bed bug physiology

BACKGROUND

Cimex lectularius L. (bed bug) (Hemiptera: Cimicidae) is a serious indoor pest worldwide, and this nuisance needs to be controlled using different methods in integrated pest management (IPM). Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) kills bed bugs, and insect pathogenic fungi may be utilized to control bed bugs in IPM. To increase knowledge of this methodology, forced exposure experiments were conducted with different formulations, doses, and substrates, using bed bugs in variable physiological states.

RESULTS

Both oil- and water-formulated fungal products showed significant improvement when conidial concentrations were raised in five steps from 0.02 to 2.0%. At low concentrations (0.02% in water) effects from substrate and application strategy were observed. Application on soft substrates (cotton and polyester) yielded significantly higher bed bug mortality rates than on harder substrates (paper, wood, and linoleum) with a final mortality of 35-63% against 8-10%. Multiple applications over time also improved B. bassiana's ability to kill bed bugs, and at low concentrations only a triple application on cotton showed 100% final mortality. Bed bug age and reproductive status significantly affected survival. Older and reproducing individuals showed higher mortality compared to newly emerged adults. Differences in feeding status also yielded differences in mortality timing, but only minor differences in final mortality rates. Egg production and hatching success were significantly reduced by some treatments.

CONCLUSION

B. bassiana appears to be an asset in the fight against bed bugs. Substrate, dosage, application strategy, and bed bug physiology are important factors to consider for optimal efficacy and safe indoor control with insect pathogenic fungi. © 2023 Society of Chemical Industry.

Metabolomics Analysis of Sporulation-Associated Metabolites of Metarhizium anisopliae Based on Gas Chromatography-Mass Spectrometry

Metarhizium anisopliae, an entomopathogenic fungus, has been widely used for the control of agricultural and forestry pests. However, sporulation degeneration occurs frequently during the process of successive culture, and we currently lack a clear understanding of the underlying mechanisms. In this study, the metabolic profiles of M. anisopliae were comparatively analyzed based on the metabolomics approach of gas chromatography-mass spectrometry (GC-MS). A total of 74 metabolites were detected in both normal and degenerate strains, with 40 differential metabolites contributing significantly to the model. Principal component analysis (PCA) and potential structure discriminant analysis (PLS-DA) showed a clear distinction between the sporulation of normal strains and degenerate strains. Specifically, 23 metabolites were down-regulated and 17 metabolites were up-regulated in degenerate strains compared to normal strains. The KEGG enrichment analysis identified 47 significant pathways. Among them, the alanine, aspartate and glutamate metabolic pathways and the glycine, serine and threonine metabolism had the most significant effects on sporulation, which revealed that significant changes occur in the metabolic phenotypes of strains during sporulation and degeneration processes. Furthermore, our subsequent experiments have substantiated that the addition of amino acids could improve M. anisopliae's spore production. Our study shows that metabolites, especially amino acids, which are significantly up-regulated or down-regulated during the sporulation and degeneration of M. anisopliae, may be involved in the sporulation process of M. anisopliae, and amino acid metabolism (especially glutamate, aspartate, serine, glycine, arginine and leucine) may be an important part of the sporulation mechanism of M. anisopliae. This study provides a foundation and technical support for rejuvenation and production improvement strategies for M. anisopliae.

Efficacy and nontarget effects of broadcast treatments to manage spotted lanternfly (Hemiptera: Fulgoridae) nymphs

Management to control the spotted lanternfly, Lycorma delicatula (White), would ideally achieve managers' goals while limiting impacts on nontarget organisms. In a large-scale field study with 45 plots at least 711 m2, we tested foliar applications of dinotefuran and 2 formulations of Beauveria bassiana (Balsamo) Vuillemin, each applied from the ground and separately by helicopter. Applications targeted early instar nymphs. For both application methods, a single treatment with dinotefuran significantly reduced L. delicatula numbers, as measured by catch on sticky bands (91% reduction by air and 84% reduction by ground 19 days after application) and by timed counts (89% reduction by air and 72% reduction by ground 17 days after application). None of the B. bassiana treatments significantly reduced L. delicatula numbers, even after 3 applications. Beauveria bassiana infection in field-collected nymphs ranged from 0.4% to 39.7%, with higher mortality and infection among nymphs collected from ground application plots. Beauveria bassiana conidia did not persist for long on foliage which probably contributed to low population reduction. Nontarget effects were not observed among arthropods captured in blue vane flight intercept traps, San Jose Scale pheromone sticky traps or pitfall traps, but power analysis revealed that small reductions of less than 40% may not be detected despite extensive sampling of 48,804 specimens. These results demonstrate that dinotefuran can markedly reduce local abundance of L. delicatula with little apparent effect on nontarget insects when applied shortly after hatch, and that aerial applications can match or exceed the effectiveness of applications from the ground.

Post-Application Field Persistence and Efficacy of Cordyceps javanica against Bemisia tabaci

Previously, Cordyceps javanica Wf GA17, a causing agent of whitefly epizootics in southern Georgia, demonstrated superior temperature tolerance and higher virulence against the whitefly Bemisia tabaci than commercial strains in the laboratory. The post-application persistence and efficacy of this fungus against B. tabaci were compared with that of the commercially available C. javanica Apopka97 strain over a two-year field study in cotton and vegetable crops. When blastospores of both strains were applied alone, whitefly populations were not effectively suppressed. Thus, JMS stylet oil was added to fungal treatments for enhancing efficacy and persistence. For 0-day samples, all fungal treatments caused similar but significant levels of immature mortality regardless of fungal strain, propagule form (conidia vs. blastospores), and application method (alone or mixed with JMS). In follow-up samplings, Wf GA17 blastospores + JMS achieved higher control levels than other treatments in some trials, but the efficacy did not last long. The JMS oil alone caused significant mortality and suppressed whiteflies. Over 90% of spores lost viability 24 h after treatment in all fungal treatments. Across evaluation times, there was no difference between the two fungal strains (conidia or blastospores, alone or combined with JMS), but conidia persisted better than blastospores for both strains. Overall, the field persistence and efficacy of C. javanica did not last long; therefore, improved delivery methods and formulations are needed for enhancement.

Assessment of nematicidal and plant growth-promoting effects of Burkholderia sp. JB-2 in root-knot nematode-infested soil

Root-knot nematodes (RKN), Meloidogyne spp., are plant-parasitic nematodes that are responsible for considerable economic losses worldwide, because of the damage they cause to numerous plant species and the inadequate biological agents available to combat them. Therefore, developing novel and eco-friendly nematicides is necessary. In the present study, Burkholderia sp. JB-2, isolated from RKN-infested rhizosphere soil in South Korea, was evaluated to determine its nematicidal and plant growth-promoting effects under in vitro and in vivo conditions. Cell-free filtrates of the JB-2 strain showed high levels of nematicidal activity against second-stage juveniles (J2) of M. incognita, with 87.5% mortality following two days of treatment. In addition, the assessment of the activity against other six plant parasitic nematodes (M. javanica, M. hapla, M. arenaria, Ditylenchus destructor, Aphelenchoides subtenuis, and Heterodera trifolii) showed that the cell-free filtrates have a broad nematicidal spectrum. The three defense-responsive (MiMIF-2, MiDaf16-like1, and MiSkn1-like1) genes were activated, while Mi-cm-3 was downregulated when treated with cell-free filtrates of JB-2 cultures on J2. The greenhouse experiments suggested that the cell-free filtrates of the JB-2 strain efficiently controlled the nematode population in soil and egg mass formations of M. incognita in tomato (Solanum lycopersicum L., cv. Rutgers). An improvement in the host plant growth was observed, in which the shoot length and fresh weights of shoots and roots increased. The treatment with 10% of JB-2 cell-free filtrates significantly upregulated the expression levels of plant defenses (SlPR1, SlPR5, and SlPAL) and growth-promoting (ACO1, Exp18, and SlIAA1) genes compared with the corresponding parameters of the control group. Therefore, JB-2 could be a promising candidate for the sustainable management of RKN.

Key amino acids residues enhance the ability of CpcR to activate cry gene expression in Bacillus thuringiensis

Typical Bacillus thuringiensis (Bt) produces one or more parasporal crystals composed of insecticidal Cry proteins during the sporulation, and the parasporal crystals and spores are produced from the same cell. Strain Bt LM1212 is different from typical Bt strains in that its crystals and spores are produced in different cells. Previous studies have found that the cell differentiation process of Bt LM1212 is related to the transcription factor CpcR which activates the cry-gene promoters. In addition, CpcR could activate the Bt LM1212 cry35-like gene promoter (P35) when introduced in the heterologous HD73- strain. It was shown that P35 was only activated in non-sporulating cells. In this study, the peptidic sequences of CpcR homologous proteins found in other strains of the Bacillus cereus group were used as references to identify two key amino acid sites for CpcR activity. The function of these amino acids was investigated by measuring P35 activation by CpcR in strain HD73-. These results will lay a foundation for the optimization of the insecticidal protein expression system in non-sporulating cells.

De novo genome assembly of Akanthomyces muscarius, a biocontrol agent of insect agricultural pests

The entomopathogenic fungus Akanthomyces muscarius is commonly used in agriculture to manage insect pests. Besides its use as a commercially important biological control agent, it also presents a potential model for studying host-pathogen interactions and the evolution of virulence in a laboratory setting. Here, we describe the first high-quality genome sequence for A. muscarius. We used long- and short-read sequencing to assemble a sequence of 36.1 Mb with an N50 of 4.9 Mb. Genome annotation predicted 12347 genes, with 96.6 % completeness based on the core Hypocrealen gene set. The high-quality assembly and annotation of A. muscarius presented in this study provides an essential tool for future research on this commercially important species.

Plant Seeds Commonly Host Bacillus spp., Potential Antagonists of Phytopathogens

In agriculture, horticulture and plantation forestry, Bacillus species are the most commonly applied antagonists and biopesticides, targeting plant pathogens and insect pests, respectively. Bacillus isolates are also used as bacterial plant biostimulants, or BPBs. Such useful isolates of Bacillus are typically sourced from soil. Here, we show that Bacillus - and other antagonistic microbes - can be sourced from a broad range of plant seeds. We found that culturable Bacillus isolates are common in the seeds of 98 plant species representing 39 families (i.e., 87% of the commonly cultured bacteria belonged to Bacillales). We also found that 83% of the commonly cultured fungi from the seeds of the 98 plant species belonged to just three orders of fungi-Pleosporales, Hypocreales and Eurotiales-that are also associated with antagonism. Furthermore, we confirmed antagonism potential in agaro with seed isolates of Bacillus from Pinus monticola as a representative case. Eight isolates each of seed Bacillus, seed fungi, and foliar fungi, all from P. monticola, were paired in a total of 384 possible pair-wise interactions (with seed and foliar fungi as the targets). Seed Bacillus spp. were the strongest antagonists of the seed and foliar fungi, with a mean interaction strength 2.8 times greater than seed fungi (all either Eurotiales or Hypocreales) and 3.2 times greater than needle fungi. Overall, our study demonstrates that seeds host a taxonomically narrow group of culturable, antagonistic bacteria and fungi.

Effects of Lymantria dispar multiple nucleopolyhedrovirus and Bacillus thuringiensis var. kurstaki on different larval instars of Lymantria dispar asiatica

Outbreaks of Lymantria dispar asiatica (the Asian spongy moth; Lepidoptera: Erebidae) occur sporadically, causing widespread damage to forest and fruit trees. Owing to the development of pesticide resistance and environmental contamination, biopesticides, including L. dispar multiple nucleopolyhedrovirus (LdMNPV) and Bacillus thuringiensis var. kurstaki (Btk), can significantly contribute to controlling overall larval stage of this species. Although both pathogens are highly effective at the larval stage, their effects on different instar stages have not been investigated. In this study, we analyzed the mortality and lethality in different L. dispar asiatica instars exposed to single or combined pathogen treatments. Treatments with low or medium LdMNPV concentrations induced lower mortality and had higher LT₅₀ values at the 4th and 5th instars compared with other instars, whereas high LdMNPV treatments induced high mortality in all instars, with higher LT₅₀ values at later instars. Treatment with Btk induced a rapid 100% mortality in all instars, with higher LT₅₀ values for the later instars. The combination of LdMNPV and Btk delayed the killing time compared with the effects of single treatments, with the effect being more pronounced in the 1st and 5th instar stage than at other stages at low Btk concentrations. Our findings indicate that the pathogenic effects of LdMNPV and Btk on L. dispar asiatica differ according to larval stage, thereby providing novel insights into enhancing the biological control efficacy of these agents against L. dispar asiatica in the field.

Cryptic diversity and virulence of Beauveria bassiana recovered from Lycorma delicatula (spotted lanternfly) in eastern Pennsylvania

The entomopathogenic fungus Beauveria bassiana is cosmopolitan and known to infect a variety of sap-sucking pests like aphids, mealybugs, and scales in the order of Hemiptera. In Fall 2017, spotted lanternfly (SLF) adults killed by the fungal entomopathogen B. bassiana were found in Berks County, Pennsylvania. In 2018-2020 we collected SLF and nearby non-target insects killed by Beauveria spp. from 18 field sites in southeastern Pennsylvania. We identified 159 Beauveria isolates from SLF and six isolates from non-targets. Five isolates of B. bassiana and one isolate of B. brongniartii were identified from the non-targets. Based on sequence data from the nuclear B locus (Bloc) intergenic region, all the isolates from SLF were identified as B. bassiana, but there were 20 different strains within this species, grouped into two clades. Three B. bassiana strains (A, B, and L) were found in most field sites and were the most prevalent. Representative isolates for these three strains were used in laboratory bioassays and were compared to a commercial B. bassiana strain (GHA). Strain B was inferior to A, L, and GHA against nymphs; strains A and L had greater efficacy than B and GHA against adults. We also quantified conidial production on SLF cadavers. This paper discusses the diversity of these B. bassiana strains in SLF populations and implications for biological control of this abundant invasive.

Integrated pest management of Hypsipyla robusta shoot-tip borer (Lepidoptera: Pyralidae) in Chukrasia tabularis (Sapindales: Meliaceae)

Chukrasia tabularis A. Juss produces a valuable timber but plantations are susceptible to attack by the shoot-tip borer Hypsipyla robusta Moore. An integrated pest management (IPM) approach is desirable to limit the extent of damage. Therefore, this study was undertaken to evaluate the deployment of IPM measures in plantations in Vietnam. Data on tree damage and the biology of H. robusta were gathered in 4 provinces over one year and used to build an investigation schedule. Two preliminary IPM trials were then established in which Bacillus thuringiensis and Metarhizium anisopliae were applied to the foliage when the damage incidence (P%) was in the range 5-10%; and insecticides (Carbaryl, Carbosulfan) were applied when the P% exceeded 10%. In addition, larvae and pupae were removed manually over time. In the first trial, the combination of manual and biological control methods reduced the damage index (DI) of trees from 4 tolerant families by 82% compared to the untreated control plots. In the second trial using standard planting stock, application of insecticides was required to reduce the DI by 83%. Six extended IPM trials were undertaken using the same IPM protocols and these reduced the DI to the same extent as in the preliminary trials. Over an 18-month period, the deployment of IPM increased height growth by 19-22% and diameter growth by 38-41% compared to the controls. These findings highlight the value of planting improved seed and the benefit of adopting an IPM approach to manage the shoot-tip borer.

Volatile Metabolites from Brevundimonas diminuta and Nematicidal Esters Inhibit Meloidogyne javanica

Brevundimonas diminuta is broadly distributed in terrestrial and aquatic environments and has various biological activities. In this study, we found that B. diminuta exhibited nematicidal activity against the plant root-knot nematode, Meloidogyne javanica. A total of 42 volatile organic compounds (VOCs) from B. diminuta were identified using gas chromatography-mass spectrometry (GC-MS). The nematicidal activity of the 10 main VOCs was tested against M. javanica. Butyl butanoate (4 µL) caused the mortality of 80.13% of M. javanica after 4 h. The nematicidal activity of an additional 38 butyl-butyrate-like volatile esters was also investigated. Of these, seven had strong nematicidal activity against M. javanica, five of which showed egg-hatching inhibitory activity. This study is the first to report that butyl butanoate, ethyl 2-methylbutanoate, ethyl 4-methylpentanoate, ethyl pent-4-enoate, and methyl undecanoate have nematicidal activity against M. javanica. The results indicated that B. diminuta could serve as a candidate microorganism for the biocontrol of plant root-knot nematodes, showing that volatile esters have great potential as nematicides.

Bacillus thuringiensis-Based Bioproduct: Characterization and Performance Against Spodoptera frugiperda Strains in Maize Under Different Environmental Temperatures

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is an important pest in several regions being the use of Bacillus thuringiensis-based bioproducts an alternative for its control. Firstly, 3 L of an aqueous bioproduct suspension was produced and characterized. Its 50% lethal concentration against molecularly identified corn and rice S. frugiperda strains using an artificial diet were 77.01% (95% CL, 68.16-90.47) and 2.22% (95% CL, 0.01-6.68), respectively. The next objective of this work was to evaluate the performance of this bioproduct in maize against S. frugiperda strains under different simulated agrological regions mimicking their corresponding periodic day/night temperatures. Thus, the impact of environmental temperature on the bioproduct efficacy (E) was studied. It was observed that a warmer scenario (35 °C day/30 °C night) could favor the tolerance of corn S. frugiperda strain to the bioproduct (E = 56.36 ± 0.61%) maintaining a high efficacy (92.44 ± 6.55%) when it was tested against rice S. frugiperda strain. Conversely, under temperate conditions, efficacy values ranged from 84 to 95% for both S. frugiperda strains. On the other hand, based on a foliar feeding damage analysis, our bioproduct displayed a significant foliar protection in maize plants infested with either corn or rice S. frugiperda strains.

Genomic–proteomic analysis of a novel Bacillus thuringiensis strain: toxicity against two lepidopteran pests, abundance of Cry1Ac5 toxin, and presence of InhA1 virulence factor

Bacillus thuringiensis (Bt) is a biological alternative to the indiscriminate use of chemical insecticides in agriculture. Due to resistance development on insect pests to Bt crops, isolating novel Bt strains is a strategy for screening new pesticidal proteins or strains containing toxin profile variety that can delay resistance. Besides, the combined genomic and proteomic approaches allow identifying pesticidal proteins and virulence factors accurately. Here, the genome of a novel Bt strain (Bt TOL651) was sequenced, and the proteins from the spore-crystal mixture were identified by proteomic analysis. Toxicity bioassays with the spore-crystal mixture against larvae of Diatraea saccharalis and Anticarsia gemmatalis, key pests of sugarcane and soybean, respectively, were performed. The toxicity of Bt TOL651 varies with the insect; A. gemmatalis (LC₅₀ = 1.45 ng cm^-2) is more susceptible than D. saccharalis (LC₅₀ = 73.77 ng cm^-2). Phylogenetic analysis of the gyrB gene indicates that TOL651 is related to Bt kenyae strains. The genomic analysis revealed the presence of cry1Aa18, cry1Ac5, cry1Ia44, and cry2Aa9 pesticidal genes. Virulence factor genes such as phospholipases (plcA, piplc), metalloproteases (inhA), hemolysins (cytK, hlyIII, hblA, hblC, hblD), and enterotoxins (nheA, nheB, nheC) were also identified. The combined use of the genomic and proteomic data indicated the expression of Cry1Aa18, Cry1Ac5, and Cry2Aa9 proteins, with Cry1Ac5 being the most abundant. InhA1 also was expressed and may contribute to Bt TOL651 pathogenicity. These results provide Bt TOL651 as a new tool for the biocontrol of lepidopteran pests.

Preparation and Evaluation of Zeolite Nanoparticles as a Delivery System for Helicoverpa armigera Nucleopolyhedrovirus (HaNPV) against the Spodoptera litura (Fabricius, 1775) Larvae

Synthetic insecticides frequently cause pest resistance and destroy non-target organisms. Thus, virus formulation is an issue that deserves considerable attention in developing virus-based insecticides. The hindrance of using nucleopolyhedrovirus alone as a virus-based insecticide is due to slow lethal time, though its mortality remains high (100%). This paper reports the formulation of zeolite nanoparticles as a delivery system to accelerate lethal time in controlling Spodoptera litura (Fabr.). Zeolite nanoparticles were prepared using the beads-milling method. The statistical analysis was carried out by a description exploration method with six replications. The occlusion bodies’ concentration in the virus formulation was 4 × 107 OBs in 1 mL medium. Zeolite nanoparticles formulation sped up the lethal time significantly (7.67 days) compared to micro-size zeolite (12.70 days) and only nucleopolyhedrovirus (8.12 days) and received acceptable mortality (86.4%). The zeolite nanoparticles delivery system provides an alternative formulation for nucleopolyhedrovirus with a significantly improved speed of killing the virus while maintaining suitable efficacy of the virus preparation in terms of the prevalence of mortality.

Biopesticides as a promising alternative to synthetic pesticides: A case for microbial pesticides, phytopesticides, and nanobiopesticides

Over the years, synthetic pesticides like herbicides, algicides, miticides, bactericides, fumigants, termiticides, repellents, insecticides, molluscicides, nematicides, and pheromones have been used to improve crop yield. When pesticides are used, the over-application and excess discharge into water bodies during rainfall often lead to death of fish and other aquatic life. Even when the fishes still live, their consumption by humans may lead to the biomagnification of chemicals in the body system and can cause deadly diseases, such as cancer, kidney diseases, diabetes, liver dysfunction, eczema, neurological destruction, cardiovascular diseases, and so on. Equally, synthetic pesticides harm the soil texture, soil microbes, animals, and plants. The dangers associated with the use of synthetic pesticides have necessitated the need for alternative use of organic pesticides (biopesticides), which are cheaper, environment friendly, and sustainable. Biopesticides can be sourced from microbes (e.g., metabolites), plants (e.g., from their exudates, essential oil, and extracts from bark, root, and leaves), and nanoparticles of biological origin (e.g., silver and gold nanoparticles). Unlike synthetic pesticides, microbial pesticides are specific in action, can be easily sourced without the need for expensive chemicals, and are environmentally sustainable without residual effects. Phytopesticides have myriad of phytochemical compounds that make them exhibit various mechanisms of action, likewise, they are not associated with the release of greenhouse gases and are of lesser risks to human health compared to the available synthetic pesticides. Nanobiopesticides have higher pesticidal activity, targeted or controlled release with top-notch biocompatibility and biodegradability. In this review, we examined the different types of pesticides, the merits, and demerits of synthetic pesticides and biopesticides, but more importantly, we x-rayed appropriate and sustainable approaches to improve the acceptability and commercial usage of microbial pesticides, phytopesticides, and nanobiopesticides for plant nutrition, crop protection/yield, animal/human health promotion, and their possible incorporation into the integrated pest management system.

Spodoptera exigua Multiple Nucleopolyhedrovirus Increases the Susceptibility to Insecticides: A Promising Efficient Way for Pest Resistance Management

Spodoptera exigua is a polyphagous pest of diverse crops and causes considerable economic losses. The overuse of chemical insecticides for controlling this pest results in insecticide resistance, environmental pollution and toxicity to other non-target organisms. Therefore, a sustainable and efficient way for pest management is urgently required. In this study, laboratory bioassays of eleven commonly used insecticides, the specific entomopathogen of S. exigua (Spodoptera exigua multiple nucleopolyhedrovirus, SeMNPV), and SeMNPV-insecticide combinations against the S. exigua laboratory population and two field populations were tested. Our results indicated that the two field populations had developed resistance to almost half of the tested insecticides, while SeMNPV had good virulence in all populations. Interestingly, the combined use of SeMNPV enhanced the toxicity of the tested insecticides against all populations to a different extent and considerably reduced the insecticide resistance of S. exigua field populations or even recovered the susceptibility to above insecticides. Furthermore, the field trial showed that the combined application of SeMNPV contributed to promoting the control efficacy of emamectin benzonate and chlorfenapyr. These results provide a promising efficient way for pest resistance management and an environmentally friendly approach for controlling S. exigua with the combined application of nucleopolyhedroviruses and insecticides.

Towards Sustainable Green Adjuvants for Microbial Pesticides: Recent Progress, Upcoming Challenges, and Future Perspectives

Microbial pesticides can be significantly improved by adjuvants. At present, microbial pesticide formulations are mainly wettable powders and suspension concentrations, which are usually produced with adjuvants such as surfactants, carriers, protective agents, and nutritional adjuvants. Surfactants can improve the tension between liquid pesticides and crop surfaces, resulting in stronger permeability and wettability of the formulations. Carriers are inert components of loaded or diluted pesticides, which can control the release of active components at appropriate times. Protective agents are able to help microorganisms to resist in adverse environments. Nutritional adjuvants are used to provide nutrients for microorganisms in microbial pesticides. Most of the adjuvants used in microbial pesticides still refer to those of chemical pesticides. However, some adjuvants may have harmful effects on non-target organisms and ecological environments. Herein, in order to promote research and improvement of microbial pesticides, the types of microbial pesticide formulations were briefly reviewed, and research progress of adjuvants and their applications in microbial pesticides were highlighted, the challenges and the future perspectives towards sustainable green adjuvants of microbial pesticides were also discussed in this review.

A comprehensive review on advances in storage pest management: Current scenario and future prospects

Modernization of the agricultural production system led to a significant increase in annual food production intended to meet the ever-growing consumer demand. In many countries, most of the food grains produced is stored for contingency and regular supply. These stored grains, in general, are directly or indirectly infested by insects, resulting in severe grain damages and storage losses, thus, causing a threat to food safety and security. Although a variety of insect management options, such as physical, mechanical, biological, and chemical methods, are available, fumigation has been practiced for decades in storage. However, opportunities for fumigation are narrowing after the phase-out of methyl bromide. Besides, safe food and health concerns paved the path for green chemistry and non-chemical management practices. This review includes the list of stored-grain insects and their detection methods. The different management strategies such as the modern storage structures (hermetic and low-pressure storages), modified or controlled storage atmosphere, application of ozone as fumigant, irradiation, and physical options are presented. Further, the details on sustainable biological options, such as semiochemicals, natural enemies, biopesticides, and entomopathogenic nematodes, are supplemented. The use of inert dusts as grain protectant and in combination with the biological entity is included. Studies on alternative fumigants', novel management options, such as molecular biology tools (RNAi and CRISPR) and nanotechnology in stored grain protection, are also highlighted. This review helps the reader to understand the overall factors affecting grain storage and the different options to manage the insects causing storage losses.

High-Throughput Sequencing as a Tool for the Quality Control of Microbial Bioformulations for Agriculture

Microbial bioformulations, due to their positive impact on the growth and development of plants, as well as the absence of harmful effects on the environment and humans, have a vast potential for mass introduction into agriculture. Assessing the quality of bioformulations, especially complex ones, is a difficult task. In this study, we show that high-throughput sequencing can be an effective tool for the quality control and safety of microbial bioformulations. By the method of high-throughput sequencing on the MiSeq platform, we studied 20 samples of commercially available microbial bioformulations. In parallel with this, bioformulations were studied by classical microbiological methods. The analysis showed the presence of extraneous undeclared bacterial genera by the manufacturer. Only 10% of the bioformulations fully corresponded to the commercial composition, and another 10% of the bioformulations did not contain the bacteria declared by the manufacturer in their composition at all. The bacterial composition of 80% of the bioformulations partially corresponded to the composition indicated on the package. The most frequent microbial bioformulations contaminants were Enterococcus, Lactobacillaceae, Klebsiella, Escherichia-Shigella and Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium. Universal methods for the quality control of bioformulations are needed. The advantages of high-throughput sequencing for the evaluation of bioformulations are considered in this work.

Larval Mortality and Ovipositional Preference in Aedes albopictus (Diptera: Culicidae) Induced by the Entomopathogenic Fungus Beauveria bassiana (Hypocreales: Cordycipitaceae)

Entomopathogenic fungi allow chemical-free and environmentally safe vector management. Beauveria bassiana (Balsamo-Crivelli) Vuillemin is a promising biological control agent and an important component of integrated vector management. We investigated the mortality of Aedes albopictus (Skuse) larvae exposed to five concentrations of B. bassiana using Mycotrol ESO and adult oviposition behavior to analyze the egg-laying preferences of wild Ae. albopictus in response to different fungal concentrations. We examined the mortality of mid-instars exposed to B. bassiana concentrations of 1 × 104, 1 × 105, 1 × 106, 1 × 107, and 1 × 108 conidia/ml every 24 h for 12 d. In the oviposition behavior study, the fungus was applied to wooden paddles at 1 × 105, 1 × 107, and 1 × 109 conidia/ml, and the paddles were individually placed into quad-ovitraps. Both experiments contained control groups without B. bassiana. Kaplan-Meier survival analysis revealed that larval mortality was concentration dependent. The median lethal concentration was 2.43 × 105 conidia/ml on d 12. The median lethal time was 3.68 d at 1 × 106 conidia/ml. Oviposition monitoring revealed no significant difference in egg count between the control and treatment paddles. We observed an inverse relationship between the concentration of B. bassiana and the percentage of paddles with eggs. We concluded that concentrations above 1 × 106 conidia/ml are larvicidal, and Ae. albopictus laid similar numbers of eggs on fungus-impregnated and control wooden substrates; however, they were more likely to oviposit on substrates without B. bassiana. With these findings, we suggest that B. bassiana-infused ovitraps can be used for mosquito population monitoring while also delivering mycopesticides to adult mosquitoes.

Laboratory Risk Assessment of Three Entomopathogenic Fungi Used for Pest Control toward Social Bee Pollinators

The use of fungal-based biopesticides to reduce pest damage and protect crop quality is often considered a low-risk control strategy. Nevertheless, risk assessment of mycopesticides is still needed since pests and beneficial insects, such as pollinators, co-exist in the same agroecosystem where mass use of this strategy occurs. In this context, we evaluated the effect of five concentrations of three commercial entomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae, and Cordyceps fumosorosea, by direct contact and ingestion, on the tropical stingless bees Scaptotrigona depilis and Tetragonisca angustula, temperate bee species, the honey bee Apis mellifera, and the bumble bee Bombus terrestris, at the individual level. Furthermore, we studied the potential of two infection routes, either by direct contact or ingestion. In general, all three fungi caused considerable mortalities in the four bee species, which differed in their response to the different fungal species. Scaptotrigona depilis and B. terrestris were more susceptible to B. bassiana than the other fungi when exposed topically, and B. terrestris and A. mellifera were more susceptible to M. anisopliae when exposed orally. Interestingly, increased positive concentration responses were not observed for all fungal species and application methods. For example, B. terrestris mortalities were similar at the lowest and highest fungal concentrations for both exposure methods. This study demonstrates that under laboratory conditions, the three fungal species can potentially reduce the survival of social bees at the individual level. However, further colony and field studies are needed to elucidate the susceptibility of these fungi towards social bees to fully assess the ecological risks.

Biopesticides and insect pollinators: Detrimental effects, outdated guidelines, and future directions

As synthetic pesticides play a major role in pollinator decline worldwide, biopesticides have been gaining increased attention to develop more sustainable methods for pest management in agriculture. These biocontrol agents are usually considered as safe for non-target species, such as pollinators. Unfortunately, when it comes to non-target insects, only the acute or chronic effects on survival following exposure to biopesticides are tested. Although international boards have highlighted the need to include also behavioral and morphophysiological traits when assessing risks of plant protection products on pollinators, no substantial concerns have been raised about the risks associated with sublethal exposure to these substances. Here, we provide a comprehensive review of the studies investigating the potential adverse effects of biopesticides on different taxa of pollinators (bees, butterflies, moths, beetles, flies, and wasps). We highlight the fragmentary knowledge on this topic and the lack of a systematic investigation of these negative effects of biopesticides on insect pollinators. We show that all the major classes of biopesticides, besides their direct toxicity, can also cause a plethora of more subtle detrimental effects in both solitary and social species of pollinators. Although research in this field is growing, the current risk assesment approach does not suffice to properly assess all the potential side-effects that these agents of control may have on pollinating insects. Given the urgent need for a sustainable agriculture and wildlife protection, it appears compelling that these so far neglected detrimental effects should be thoroughly assessed before allegedly safe biopesticides can be used in the field and, in this view, we provide a perspective for future directions.

Acaricidal Activity and Field Efficacy Analysis of the Potential Biocontrol Agent Bacillus vallismortis NBIF-001 against Spider Mites

In recent years, spider mites have caused considerable economic losses to global agriculture. However, currently available management strategies are limited because of the rapid development of resistance. In this study, Bacillus vallismortis NBIF-001 was isolated and evaluated for its acaricidal activity. NBIF-001 exhibited a significant lethal effect on spider mites within 48 h. The median lethal concentration (LC₅₀) of the culture powders (3.2 × 10¹⁰ CFU/g) was 50.2 µg/mL for Tetranychus urticae (red form), 18.0 µg/mL for T. urticae (green form), and 15.7 µg/mL for Panonychus citri (McGregor). Cultivation optimisation experiments showed that when the number of spores increased, fermentation toxicity also increased. Moreover, field experiments demonstrated that NBIF-001 performed well in the biocontrol of P. citri, which showed a similar corrected field efficacy with the chemical control (67.1 ± 7.9% and 71.1 ± 6.4% after 14 days). Genomics analysis showed that NBIF-001 contains 231 factors and seven gene clusters of metabolites that may be involved in its acaricidal activity. Further bioassays of the fermentation supernatants showed that 50× dilution treatments killed 72.5 ± 5.4% of the mites in 48 h, which was similar with those of the broth. Bioassays of the supernatant proteins confirmed that various proteins exhibited acaricidal activity. Five candidate proteins were expressed and purified successfully. The bioassays showed that the small protein BVP8 exhibited significant acaricidal activity with an LC₅₀ of 12.4 μg/mL (T. urticae). Overall, these findings suggest that B. vallismortis NBIF-001 is a potential biocontrol agent for spider mite management.

Efficient and Scalable Process to Produce Novel and Highly Bioactive Purified Cytosolic Crystals from Bacillus thuringiensis

Bacillus thuringiensis (Bt) is a Gram-positive soil bacterium that is widely and safely applied in the environment as an insecticide for combatting insect pests that damage crops or are disease vectors. Dominant active ingredients made by Bt are insect-killing crystal (Cry) proteins released as crystalline inclusions upon bacterial sporulation. Some Bt Cry proteins, e.g., Cry5B (formally Cry5Ba1), target nematodes (roundworms) and show exceptional promise as anthelmintics (cures for parasitic nematode diseases). We have recently described inactivated bacteria with cytosolic crystal(s) (IBaCC) in which bioactive Bt Cry crystals (containing Cry5B) are fully contained within the cytosol of dead bacterial ghosts. Here, we demonstrate that these IBaCC-trapped Cry5B crystals can be liberated and purified away from cellular constituents, yielding purified cytosolic crystals (PCC). Cry5B PCC contains ~95% Cry5B protein out of the total protein content. Cry5B PCC is highly bioactive against parasitic nematode larvae and adults in vitro. Cry5B PCC is also highly active in vivo against experimental human hookworm and Ascaris infections in rodents. The process was scaled up to the 100-liter scale to produce PCC for a pilot study to treat two foals infected with the ascarid Parascaris spp. Single-dose Cry5B PCC brought the fecal egg counts of both foals to zero. These studies describe the process for the scalable production of purified Bt crystals and define a new and attractive pharmaceutical ingredient form of Bt Cry proteins.

IMPORTANCEBacillus thuringiensis crystal proteins are widely and safely used as insecticides. Recent studies have shown they also can cure gastrointestinal parasitic worm (nematode) infections when ingested. However, reproducible, scalable, and practical techniques for purifying these proteins have been lacking. Here, we address this severe limitation and present scalable and practical methods for large-scale purification of potently bioactive B. thuringiensis crystals and crystal proteins. The resultant product, called purified cytosolic crystals (PCC), is highly compatible with ingestible drug delivery and formulation. Furthermore, there are growing applications in agriculture and insect control where access to large quantities of purified crystal proteins is desirable and where these methods will find great utility.

Lethal and Sublethal Toxicity Assessment of Cyclosporin C (a Fungal Toxin) against Plutella xylostella (L.)

Secondary metabolites/toxins produced by Purpeocillium lilacinum (Hypocreales; Phiocordycipitaceae), a well-known insect pathogen, can be used for the management of different insect pests. We report the lethal and sublethal effects of cyclosporin C (a toxin produced by P. lilacinum) against a major vegetable pest, Plutella xylostella, at specific organismal (feeding rate, larval growth, adult emergence, fecundity, and adult longevity) and sub-organismal levels (changes in antioxidant and neurophysiological enzyme activities). The toxicity of cyclosporin C against different larval instars of P. xylostella increased with increasing concentrations of the toxin and the maximum percent mortality rates for different P. xylostella larval instars at different times were observed for the 300 µg/mL cyclosporin C treatment, with an average mortality rate of 100% for all larval instars. The median lethal concentrations (LC₅₀) of cyclosporin C against the first, second, third, and fourth larval instars of P. xylostella 72 h post-treatment were 78.05, 60.42, 50.83, and 83.05 μg/mL, respectively. Different concentrations of cyclosporin C caused a reduction in the average leaf consumption and average larval weight. Different life history parameters, such as the pupation rate (%), adult emergence (%), female fecundity, and female longevity were also inhibited when different concentrations of cyclosporin C were applied topically. The cyclosporin C concentrations inhibited the activities of different detoxifying (glutathione S-transferase, carboxylesterase, and acetylcholinesterase) and antioxidant enzyme (superoxide dismutase, catalase, and peroxidase) activities of P. xylostella when compared to the control. These findings can serve as baseline information for the development of cyclosporin C as an insect control agent, although further work on mass production, formulation, and field application is still required.

First Evidence of CpGV Resistance of Codling Moth in the USA

Codling moth (Cydia pomonella L.) is a very important pest in apple, pear, and walnut orchards worldwide, including the USA. Cydia pomonella granulovirus (CpGV) is used to control codling moth in organic and conventional production. Due to increasing codling moth infestations from organic apple orchards in Washington State, USA, five codling moth colonies (WA1-WA5) were screened for their susceptibility relative to the isolate GV-0001, the main active ingredient of Cyd-X^®, using a discriminating concentration of 6 × 10⁴ OB/mL. Compared to a susceptible laboratory colony, the observed results indicated that GV-0001 lacked efficacy against codling moth colony WA3. It was confirmed that WA3 was the first case of codling moth resistance to CpGV in the USA. Further testing of WA3 was performed on a range of CpGV isolates and a lack of efficacy was observed against additional isolates. However, three newly developed CpGV preparations can efficiently infect larvae from the resistant colony WA3. Our results suggest that there is an urgent need to monitor the situation in the USA, aiming to prevent the emergence or spread of additional codling moth populations with CpGV resistance. Strategies to sustain the efficacy of codling moth control using novel CpGV formulations need to be developed.

Selection and characterization of thermotolerant Beauveria bassiana isolates and with insecticidal activity against the cotton-melon aphid Aphis gossypii (Glover) (Hemiptera: Aphididae)

BACKGROUND

Cotton-melon aphid Aphis gossypii (Glover) causes severe damage mainly to cucurbits. Twenty-two Beauveria sp. isolates were simultaneously assessed for their pathogenicity and heat tolerance. The selected isolates were identified molecularly and characterized in terms of conidial germination rate, mycelial growth, conidial yield and endophytic activity.

RESULTS

Screening bioassays showed that the B. bassiana isolates B3, B7, B9 and B12 were the most toxic, inducing mortality equal to or slightly higher than the commercialized strain B. bassiana BNat (70.7%). Median lethal concentration (LC₅₀ ) bioassays revealed that only isolate B12 had a significantly lower LC₅₀ value (5.4 × 10⁵ conidia ml^-1 ) than strain BNat (5 × 10⁶ conidia ml^-1 ). The heat tolerance screening test (1 h of exposure to 45°C) allowed us to select isolates B3, B7, B9 and B12 with germination rates of 57.5% to 80.1% after 24 h incubation at 25°C, all significantly higher than strain BNat (22.1%). The germination rates of all isolates decreased significantly after 2 h of exposure to 45°C, with the exception of isolate B12 which displayed the highest thermotolerance (72% germination). The four selected isolates were able to endophytically colonize cucumber leaves when applied to the foliage. Inoculation of cucumber plants with isolate B12 did not affect cucumber plant growth. However, several plant growth parameters were improved 5 weeks after root inoculation.

CONCLUSION

On the basis of its potent toxicity and thermotolerance, isolate B12 is a good candidate for further development as a biopesticide for use in integrated pest management strategies for aphid control. © 2022 Society of Chemical Industry.

Effectiveness of a Buffalo Turbine and A1 Mist Sprayer for the Areawide Deployment of Larvicide for Mosquito Control in an Urban Residential Setting

The control of medically important container-inhabiting mosquitoes is an ongoing challenge for mosquito control operations. Truck-mounted application equipment is a common option for rapid areawide larvicide deployment utilized by mosquito control operations. We tested the effectiveness of two truck-mounted sprayers (A1 Super Duty + Buffalo Turbine CSM3), for the deployment of water-dispersible biopesticides (VectoBac WDG:VectoLex WDG 50:50). Sixty residences within four residential neighborhoods in New Jersey were treated in 2019 and 2020. Three empty bioassay cups were placed in specific locations on each property (front yard/ back yard/ side of house), with an additional cup placed in an adjacent catch basin. This approach was replicated in two untreated control neighborhoods. Following larvicide application, cups were subjected to bioassays wherein larval mortality was tracked through adult eclosion. Overall, average larval mortality rates were 56% higher in treated cups compared against untreated controls. Mortality rates were affected by cup location, with 39% mortality in bioassay cups from back yards, 54% in those from the sides of houses, 73% in front yards, and 76% from cups in catch basins. Mortality did not differ significantly between the four treated neighborhoods, nor by the type of sprayer used. Our research shows that truck-mounted sprayers can be an effective method for larvicide deployment in residential neighborhoods, but effectiveness may depend upon the location of the target treatment area in relation to residences and other geographic obstacles.

Biological Control of Plant Pathogens: A Global Perspective

The increase in the world population has generated an important need for both quality and quantity agricultural products, which has led to a significant surge in the use of chemical pesticides to fight crop diseases. Consumers, however, have become very concerned in recent years over the side effects of chemical fungicides on human health and the environment. As a result, research into alternative solutions to protect crops has been imposed and attracted wide attention from researchers worldwide. Among these alternatives, biological controls through beneficial microorganisms have gained considerable importance, whilst several biological control agents (BCAs) have been screened, among them Bacillus, Pantoea, Streptomyces, Trichoderma, Clonostachys, Pseudomonas, Burkholderia, and certain yeasts. At present, biopesticide products have been developed and marketed either to fight leaf diseases, root diseases, or fruit storage diseases. However, no positive correlation has been observed between the number of screened BCAs and available marketed products. Therefore, this review emphasizes the development of biofungicides products from screening to marketing and the problems that hinder their development. Finally, particular attention was given to the gaps observed in this sector and factors that hamper its development, particularly in terms of efficacy and legislation procedures.

A Review of Commercial Metarhizium- and Beauveria-Based Biopesticides for the Biological Control of Ticks in the USA

Simple Summary

Microbial biopesticides containing entomopathogenic fungi have potential in tick management. In this review, we compiled a comprehensive list of the use of commercialized Metarhizium and Beauveria-based biopesticides in the USA that have been tested against ixodid ticks under laboratory and field conditions and when used as a part of integrated tick management. Despite considerable progress in the development of fungal biopesticides over the past 20 years, the establishment of commercial products available for use against ticks continues to be slow. There is a need for the development of sustainable, nonchemical tick management strategies. Until efficacious fungus-based products become more available, tick management will rely primarily on synthetic chemical acaricides, with natural-product acaricides as the alternative.

Abstract

There is a need for the development of sustainable, nonchemical tick management strategies. Mycoacaricide and mycoinsecticide product development worldwide has focused primarily on fungi in the genera Beauveria (Hypocreales: Cordycipitaceae) and Metarhizium (Hypocreales: Clavicipitaceae). Microbial biopesticides containing entomopathogenic fungi have potential in tick management. However, despite considerable progress in the development of fungal biopesticides over the past 20 years, the establishment of commercial products available for use against ticks continues to be slow. We reviewed published scientific literature and compiled a comprehensive list of reports of the effectiveness of commercial biopesticides based on the fungal genera Metarhizium and Beauveria and registered for use in the USA against ixodid ticks under laboratory and field conditions. We also report on results when these biopesticides were used as a part of integrated tick management. Until efficacious fungus-based products become more available, tick management will rely primarily on synthetic chemical acaricides, with natural-product acaricides as the alternative.

A review of physiological resistance to insecticide stress in Nilaparvata lugens

Insecticides are widely used in agriculture as effective means to control pests. However, pests have not been completely mitigated with the increased use of insecticides. Instead, many side effects have arisen, especially the '3Rs' (resistance, resurgence, and residue). The brown planthopper, Nilaparvata lugens, is one of the most threatening rice pests. The main insecticides for controlling N. lugens belong to organochlorine, organophosphorus, carbamate, neonicotinoid and pyrethroid groups. However, metabolic enzymes, including cytochrome P450s, esterases, glutathione-S-transferases, and ATP-binding cassette transporters, effectively promote the detoxification of insecticides. Besides, mutations of neurological target sites, such as acetylcholinesterase, nicotinic acetylcholine, γ-aminobutyric acid receptor, and ryanodine receptor, result in insensitivity to insecticides. Here, we review the physiological metabolic resistance in N. lugens under insecticide stress to provide a theoretical basis for identifying and developing more effective and harmless insecticides.

Pathogenic potential of bacteria isolated from commercial biostimulants

Microbial-based products are a promising alternative to agrochemicals in sustainable agriculture. However, little is known about their impact on human health even if some of them, i.e., Bacillus and Paenibacillus species, have been increasingly implicated in different human diseases. In this study, 18 bacteria were isolated from 2 commercial biostimulants, and they were genotypically and phenotypically characterized to highlight specific virulence properties. Some isolated bacteria were identified as belonging to the genus Bacillus by BLAST and RDP analyses, a genus in-depth studied for plant growth-promoting ability. Moreover, 16S rRNA phylogenetic analysis showed that seven isolates grouped with Bacillus species while two and four clustered, respectively, with Neobacillus and Peribacillus. Unusually, bacterial strains belonging to Franconibacter and Stenotrophomonas were isolated from biostimulants. Although Bacillus species are generally considered nonpathogenic, most of the species have shown to swim, swarm, and produced biofilms, that can be related to bacterial virulence. The evaluation of toxins encoding genes revealed that five isolates had the potential ability to produce the enterotoxin T. In conclusion, the pathogenic potential of microorganisms included in commercial products should be deeply verified, in our opinion. The approach proposed in this study could help in this crucial step.

Genomic and biological characteristics of an alphabaculovirus isolated from Trabala vishnou gigantina

The oak lappet moth, Trabala vishnou gigantina is a forest insect pest that damages broad-leaf trees severely. Trabala vishnou gigantina nucleopolyhedrovirus (TrviNPV) has been isolated from a naturally infected T. vishnou gigantina larva and investigated for its biology and the potential to be a biological control agent against its insect host. TrviNPV was characterized by electron microscope of occlusion bodies (OBs), genomic sequencing and field control efficacy. TrviNPV OBs exhibited an irregular polyhedral shape varying in size from 0.99 to 3.99 μm with multiple nucleocapsids per virion. The genome of this virus was 165 657 bp in length with 40.33% GC content and encoded 146 putative ORFs including the 38 baculovirus core genes. TrviNPV is a group II alphabaculovirus that encodes F protein and lacks the gp64 gene specific to group I alphabaculoviruses. Phylogeny and Kimura-2 parameter analysis revealed TrviNPV to be a novel species and closest to ArdiNPV, EupsNPV and OrleNPV. Bioassays and field trials in a shrubland revealed that TrviNPV was virulent and effective to control T. vishnou gigantina in arid semi-desert region. This work firstly reported the whole genome of TrviNPV as well as its biological characters for a possibility to develop this virus as bio-pesticide in the future.

Selection for and Analysis of UV-Resistant Cryptophlebia Leucotreta Granulovirus-SA as a Biopesticide for Thaumatotibia leucotreta

Cryptophlebia leucotreta granulovirus-SA (CrleGV-SA) is used as a commercial biopesticide for the false codling moth, Thaumatotibia leucotreta, in citrus and other crops. The virus is sensitive to UV irradiation from sunlight, which reduces its efficacy as a biopesticide in the field. We selected a UV-resistant CrleGV-SA isolate, with more than a thousand-fold improved virulence compared to the wild-type isolate, measured by comparing LC₅₀ values. CrleGV-SA purified from infected T. leucotreta larvae was exposed to UV irradiation under controlled laboratory conditions in a climate chamber mimicking field conditions. Five cycles of UV exposure, followed by propagating the virus that retained infectivity in vivo with re-exposure to UV, were conducted to isolate and select for UV-resistant virus. Serial dilution bioassays were conducted against neonates after each UV exposure cycle. The concentration-responses of the infectious UV-exposed virus populations were compared by probit analysis with those from previous cycles and from the original CrleGV-SA virus population. NGS sequences of CrleGV-SA samples from UV exposure cycle 1 and cycle 5 were compared with the GenBank CrleGV-SA sequence. Changes in the genomes of infective virus from cycles 1 and 5 generated SNPs thought to be responsible for establishing UV tolerance. Additional SNPs, detected only in the cycle 5 sequence, may enhance UV tolerance and improve the virulence of the UV-tolerant population.

Entomopathogenic Fungi Biodiversity in the Soil of Three Provinces Located in Southwest China and First Approach to Evaluate Their Biocontrol Potential

Entomopathogenic fungi (EF), who represent active agents to control insect natural populations, usually persist in terrestrial habitats. Southwest area in China has various climate conditions and abundant plant biodiversity (crop, forest, grassy, orchard and arable areas). Nevertheless, the potential of soil-inhabitant EF as insect pest biocontrol agents, is unknown. In this study, first the EF biodiversity from soil of three provinces (Guizhou, Sichuan, and Yunnan) was surveyed. Then, the virulence of 29 isolated strains against Bemesia tabaci and Spodoptera litura was assessed. After analyzing 212 soil samples, 497 isolated fungi were identified. Out of them, 490 isolates were classified in 45 species of 24 genera, whereas the other seven isolates, belonging to Paecilomyces and Purpureocillium genera, were not identified under species level. Furthermore, the EF biodiversity from soil of Sichuan, Yunan, and Guizhou areas, analyzed by Shannon Wiener Index (SWI) was rated at 2.98, 1.89, and 2.14, while SWIs-biodiversity in crop, forest, grassy, orchard and arable areas was rated at 2.88, 2.74, 3.05, 2.39, and 2.47. SWI data suggested that soil from Sichuan area and grassy had higher EF biodiversity compared with other analyzed provinces and areas. Virulence bioassay results indicated that, out of the 29 isolates tested, 24 were pathogenic against B. tabaci and S. litura, resulting in mortality rates >10%. In conclusion, this study reports the EF distribution and biodiversity in soil from three provinces located at Southwest China, whereas their potential use as a tool for the B. tabaci and S. litura biocontrol must be further investigated.

Discovery of two hypocrealean fungi infecting spotted lanternflies, Lycorma delicatula: Metarhizium pemphigi and a novel species, Ophiocordyceps delicatula

In the eastern United States, populations of the invasive spotted lanternfly, Lycorma delicatula, can be infected by native fungal entomopathogens, including Batkoa major and Beauveria bassiana. In some areas of southeastern Pennsylvania, localized population collapses have been observed in L. delicatula populations to be caused by these pathogens. Two additional fungal pathogens were discovered infecting L. delicatula at low levels, and these were identified as Metarhizium pemphigi and Ophiocordyceps delicatula, a new species that has not been previously described. Therefore, four species of native entomopathogenic fungi have now been documented infecting this abundant, invasive planthopper that is spreading in the United States.

Efficacy of Purpureocillium lilacinum AUMC 10149 as biocontrol agent against root-knot nematode Meloidogyne incognita infecting tomato plant

Root-knot nematode Meloidogyne incognita is among the biotic factors which has greatly affected both the yield and the quality of the tomato crop. The egg parasitic nematode, Purpureocillium lilacinum (Pl) is considered as one of the most promising agents in controlling and overcoming this plant pathogen. The nematicidal effect of the native isolate Pl AUMC 10149 on second stage juvenile's survival and egg hatching of M. incognita at different times of exposure was tested in vitro. The obtained data showed that Pl gave a maximum percentage of J2 mortality (97.6%) and egg hatching inhibition (79.8%) after 72 hours of exposure. The potentiality of Pl as well as Bio-Nematon to control M. incognita infecting tomato was conducted using different times of application in vivo. Nine treatments with five replicates were used for such bioagents compared with the nematicide Oxamyl. Each seedling was inoculated with 1000 J2s of nematode/pot and 10 mL of Pl (1x1010 CFU/mL) or Bio-Nematon spore suspension (1x108 CFU/mL) 10mL/pot. The results indicated that the most effective treatments in reducing nematode population, number of galls and egg masses of M. incognita in plant roots was performed with treatment by Pl pre-planting and post-infection with Pl (Rf 1.9) giving a significant enhancement in plant length (64.9%), fresh weight (72.52%) and shoot dry weight (163.41%) without negatively impacting environment. Therefore, the present study confirmed that using P. lilacinum AUMC 10149 can be used as a practical supplement to environmentally friendly disease management of root-knot nematodes in Egypt.