Susceptibility Profiles of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) to Deltamethrin Reveal a Contrast between the Northern and the Southern Benin

Determination of chlorantraniliprole for managing Helicoverpa armigera and Spodoptera litura in cotton ecosystem

Cotton bollworm incidence and damages are high in India. In addition, it causes considerable yield loss. A new insecticide formulation Chlorantraniliprole 600 g/L SC was used along with recommended insecticides for managing Spodoptera litura and Helicoverpa armigera in two consecutive experimental trials during the period October 2021 to September 2022. Two foliar applications of Chlorantraniliprole (40 and 30 g a. i/ha) at ten days interval period reduced significantly the larval populations of H. armigera, S. litura without any phytotoxic symptoms in cotton. Chlorantraniliprole application in open field condition was found to be harmless to natural enemy (coccinellids and spiders). Even though, a temporary lessening of natural enemy populations was noticed after spray, progressively the population was increased within a week time. Cotton yield was high in chlorantraniliprole @ 40 g a. i/ha treated plot (22.66, 22.12 q/ha) when compared to untreated control. Similar effect was also noticed in the dose at 30 g a. i/ha (22.35, 21.81 q/ha) and it was statistically on par in both experiments. Residue analysis results confirming that, cotton lint, cotton seed and soil samples collected from treated (30 and 60 g a. i/ha) and untreated samples during harvest were free from chlorantraniliprole residues (below detectable levels of 0.008 μg/g).

In Silico and In Vivo Evaluation of Synthesized SCP-2 Inhibiting Compounds on Life Table Parameters of Helicoverpa armigera (Hübner)

For environment-friendly, safe and nonpersistent chemical control of a significant polyphagous insect pest, Helicoverpa armigera, discovery of growth-regulating xenobiotics can offer a sustainable alternative to conventional insecticides. For this purpose, chemically synthesized compounds to inhibit sterol carrier protein (SCP-2) function using in silico and in vivo assays were evaluated to estimate their impact on the survivals and lifetable indices of H. armigera. From nine chemically synthesized compounds, OA-02, OA-06 and OA-09 were selected for this study based on binding poses mimicking cholesterol, a natural substrate of sterol carrier protein and molecular dynamics simulations. In vivo bioassays revealed that all compounds significantly reduced the larval and pupal weight accumulations and stadia lengths. Subsequently, the pupal periods were prolonged upon treatment with higher doses of the selected compounds. Moreover, OA-09 significantly reduced pupation and adult emergence rates as well as the fertility of female moths; however, fecundity remained unaffected, in general. The life table parameters of H. armigera were significantly reduced when treated with OA-09 at higher doses. The population treated with 450 μM of OA-09 had the least net reproductive rates (Ro) and gross reproductive rate (GRR) compared to the control population. The same compound resulted in a declining survival during the early stages of development coupled with reduced larval and pupal durations, and fertility. These results have a significant implication for developing an effective and sustainable chemical treatment against H. armigera infestation.

Helicoverpa genus on the edge of the continental U.S.: Flight phenology, analysis of hybrid presence, and insecticide performance in high-input field crops in Puerto Rico

The genus Helicoverpa includes several agricultural pests globally. Helicoverpa armigera was reported in several countries in South America in 2013, and in Puerto Rico, in 2014. This territory is considered an agricultural hub, with a high-input system of seed production in the southern region of the island, and also at the edge of the continental U.S. Possible natural dispersion of populations of H. armigera from the Caribbean or other Central American regions poses a continuing risk to the U.S. This study was performed during the post-detection scenario of H. armigera in Puerto Rico, from 2018 to 2021. A year-round pheromone trapping program of adult males indicated an increase in the population from October to March and differences in the occurrence of Helicoverpa spp. between the municipalities Juan Diaz and Salinas. The proportion of H. armigera/H. zea and detection of congeneric hybrids between these species were assessed based on genital morphology and DNA analysis. Interestingly, neither H. armigera nor expected hybrids were detected in the present study. The susceptibility of H. zea populations to the insecticides Spinetoram, Emamectin benzoate, Chlorantraniliprole, and Esfenvalerate was assessed, and an overall significant effect of insecticide susceptibility was detected. Chlorantraniliprole and Emamectin benzoate had the highest efficacy. These results contribute to the Integrated Pest Management and Insect resistance management programs to Helicoverpa spp. in Puerto Rico. In addition, provide validated information to be considered in mitigation plans, in the scenario of an invasion of H. armigera in the continental U.S.

Genetic Variation and Population Structure of the Old World Bollworm Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae) in Ethiopia

Helicoverpa armigera is one of the most destructive insect pests of economically valuable crops in the world. Despite its economic importance, the population genetic structure of this insect remains unexplored in Ethiopia. To investigate the genetic diversity and population structure of H. armigera, we sampled 170 individuals from 15 populations throughout Ethiopia. We sequenced a fragment of the mitochondrial cytochrome b (cyt b) gene and five exon-primed intron-crossing (EPIC) markers. Twenty cyt b haplotypes with low-to-moderate haplotype diversity (mean Hd = 0.537) and high nucleotide diversity (mean Pi = 0.00339) were identified. The most frequently observed and widely distributed cyt b haplotype was designated as Hap_1 (67.058%), which is identical to sequences found across the globe. Tajima's D and Fu's F for the cyt b data were negative, supporting a model of population expansion. Within populations, a mean of 2.493 alleles/locus was recorded across the five EPIC loci, ranging from 1.200 to 3.600 alleles/locus. The highest mean effective number of alleles/population was 2.369 and the lowest was 1.178. The mean observed heterozygosity (HO) of the five loci (0-0.289; mean 0.104 ± 0.020) was lower than the expected heterozygosity (HE) (0.095-0.523; mean 0.258 ± 0.028). AMOVA detected significant genetic structure with 61% of the total molecular genetic variation of EPIC genotypes occurring between populations, suggesting a considerable degree of differentiation among populations. STRUCTURE analyses clustered the H. armigera populations into three distinct population groups but very low isolation by distance (R2 = 0.0132, P < 0.05).

Efficacy of Biopesticides in the Management of the Cotton Bollworm, Helicoverpa armigera (Noctuidae), under Field Conditions

Simple Summary

Cotton remains the most important cash crop in the world. The key insect pests of cotton include the African bollworm Helicoverpa armigera. This pest causes damage to crops estimated at greater than USD 2 billion per year worldwide. Excessive use of insecticides to control this pest has a negative effect on the environment, and is expensive for the farmers. The aim of this study is to explore the field efficacy of different biopesticides as an alternative to control H. armigera. Four biopesticides—namely, Eco-Bb^® (Beauveria bassiana), Bb endophyte (Beauveria bassiana), Bolldex^® (nucleopolyhedrovirus), and Delfin^® (Bacillus thuringiensis)—were evaluated and compared with the pyrethroid Karate^® (lambda-cyhalothrin) and an untreated control. Plots treated with Karate^® had significantly lower numbers of H. armigera larvae compared to the untreated control, and were comparable to the plots treated with Bolldex^®. On average, plots treated with Bolldex^® had a high seed cotton yield compared to the other treatments. Biopesticides showed a moderate reduction in the numbers of H. armigera larvae, and could thus be used within an integrated pest management programme.

Abstract

Cotton is one of the most valuable materials in the world, popularly used in the clothing industry and other products. However, its production is limited by the high infestation of insect pests. A study was conducted to evaluate the effects of different biopesticides on the control of the African bollworm (Helicoverpa armigera) under cotton field conditions. Four biopesticides—namely, Eco-Bb^® (Beauveria bassiana), Bb endophyte (Beauveria bassiana), Bolldex^® (Nucleopolyhedrovirus), and Delfin^® (Bacillus thuringiensis)—were evaluated and compared with the pyrethroid Karate^® (lambda-cyhalothrin) and an untreated control against H. armigera. Field trials were conducted at the Agriculture Research Council, Rustenburg, in the North West Province of South Africa during the 2017 and 2018 cotton seasons. The results revealed that in plots sprayed with Karate^® and Bolldex^®, the numbers of H. armigera were significantly reduced compared to the untreated controls. Plots treated with Bolldex^® had the lowest number of damaged bolls in 2017, while those treated with Karate^® had the lowest number of damaged bolls in 2018. All treated plots had significantly fewer damaged bolls when compared to the controls. A seed cotton yield of 5987 kg/ha was recorded in the plots that were treated with Bolldex^®—significantly higher than the yields from plots treated with Eco-Bb^®, Delfin^®, and Bb endophyte—in 2017. However, the yield in treatments with Eco-Bb^®, Delfin^®, and Bb endophyte was lower than that from the untreated controls during this season. In 2018, plots treated with Bolldex^® had the highest yield, at 6818 kg/ha, which was not different from the other treatments. The highest average seed cotton yield of 6400 kg/ha was recorded in the plots treated with Bolldex^®, followed by Karate^®. In summary, the efficacy of different biopesticides against H. armigera varied significantly, while the synthetic pesticide (Karate^®) and Bolldex^® resulted in more consistent control of this pest. The results suggest that biopesticides may, however, have the potential for use in the sustainable control of cotton bollworms as part of integrated pest management programmes, although further work is required to support this hypothesis.

Extraction and determination of flubendiamide insecticide in food samples: A review

Flubendiamide (FBD) is the first commercially available phthalic acid diamide that targets ryanodine receptors (RyRs) in insects, which play a major role in lepidoptera control. However, excessive use of FBD can influence the quality of treated products leading to toxic effects on human health. The availability of rapid and convenient methods for evaluating FBD amount in the environment is necessary. Therefore, analytical methods were developed for the determination of residues of FBD and its metabolite desiodo in different food matrices like tomato, cabbage, pigeon pea, apple, chilli and rice. The current review carries forward methods for FBD residues analysis in foods by using several chromatographic techniques including sample preparation steps. The comparison between the different methods employed for quantitative and qualitative analysis of food quality and safety is also discussed. Liquid chromatography (LC) is the predominant analytical method for assessing the quality of foods treated with FBD. Studies related to LC coupled multichannel detector (Ultraviolet (UV), Mass spectrometry (MS)) are also applied to detect pesticide residues. Extraction and clean up steps are essential to obtain reliable results. Moreover, this review reports the allowed limits of residues for the safety of consuming products treated with FBD.

Comparative TMT Proteomic Analysis Unveils Unique Insights into Helicoverpa armigera (Hübner) Resistance in Cajanus scarabaeoides (L.) Thouars

Pigeonpea [Cajanus cajan (L.) Millspaugh] is an economically important legume playing a crucial role in the semi-arid tropics. Pigeonpea is susceptible to Helicoverpa armigera (Hübner), which causes devastating yield losses. This pest is developing resistance to many commercially available insecticides. Therefore, crop wild relatives of pigeonpea, are being considered as potential sources of genes to expand the genetic base of cultivated pigeonpea to improve traits such as host plant resistance to pests and pathogens. Quantitative proteomic analysis was conducted using the tandem mass tag platform to identify differentially abundant proteins between IBS 3471 and ICPL 87 tolerant accession and susceptible variety to H. armigera, respectively. Leaf proteome were analysed at the vegetative and flowering/podding growth stages. H. armigera tolerance in IBS 3471 appeared to be related to enhanced defence responses, such as changes in secondary metabolite precursors, antioxidants, and the phenylpropanoid pathway. The development of larvae fed on an artificial diet with IBS 3471 lyophilised leaves showed similar inhibition with those fed on an artificial diet with quercetin concentrations with 32 mg/25 g of artificial diet. DAB staining (3,3'-diaminobenzidine) revealed a rapid accumulation of reactive oxygen species in IBS 3471. We conclude that IBS 3471 is an ideal candidate for improving the genetic base of cultivated pigeonpea, including traits for host plant resistance.

Waste candle soot derived carbon nanoparticles: A competent alternative for the management of Helicoverpaarmigera

Helicoverpaarmigera (Lepidoptera: Noctuidae) is considered as one of the foremost pests of global agriculture. This pest is contemplated for substantial economic loss apart from the socio-economic and environmental costs associated with its control. Farmers adopt several strategies for the control of this pest but the cost associated with these strategies is always a big question. This is the first time when waste-candle soot (CS) derived carbon nanoparticles (CNPs) are explored for the putative toxicity to H. armigera. In the present study, the entomotoxic effects of CNPs on H. armigera were investigated and compared with that of commercially available multi-walled carbon nanotubes (MWCNTs). Larvae fed on both the nanomaterials exhibited significant weight reduction and enhanced levels of antioxidant enzymes. Moths developed from the treated larvae exhibit very poor egg-laying capacity and poor egg hatchability. However, these entomotoxic effects were found more noticeable in larvae and moths fed on CNPs that eventually led to the complete cessation of the population build-up of H. armigera. These findings advocate the candidature of CNPs as a cost-effective alternative for efficient control of H. armigera in pest management programs.

Karyomorphological effects of two new oil formulations on Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

The cotton bollworm Helicoverpa armigera is a serious pest of many economically important crops. Since this pest has become resistant to the conventional synthetic insecticides, newer compounds and formulations are being developed against this insect pest. Many natural compounds isolated from the plants were tested against this pest. Among them Hyptis suaveolens and Melochia corchorifolia showed insecticidal properties against H. arnigera. Based on bioefficacy studies, caryophyllene and β-sitosterol were isolated from H. suaveolens and M. corchorifolia respectively. The isolated natural compounds were further developed as formulations in various combinations with neem (Azadirachta indica) and karanj (Pongamia pinnata) oils. The present study indicated that the formulations influenced the karyomorphology of H. armigera.