Control Strategies of Stored Product Pests

Feasibility of polylactic acid and essential oil composite with insecticidal properties for prevention of Sitophilus oryzae and Oryzophilus surinamensis in Sorghum and Pearl millet

Current study provides insight on the feasibility of polylactic acid (PLA) integrated with (1:1 ratio) of essential oils belonging to Ocimum gratissimum (OG) and Mentha spicata (MS) for prevention of major stored insect pests (Sitophilus oryzae and Oryzophilus surinamensis) in Sorghum and Pearl millet. A combination of OG and MS essential oils (1:1) was incorporated into the PLA polymer matrix. Further, SPME analysis of synthesized PLA showed the presence of volatiles corresponding to carvone (6.44 %) and thymol (6.22 %). Synthesized PLA composites were tested against S. oryzae and O. surinamensis using Sorghum and Pearl millets, and insect mortality was equivalent to commercial super bags (CSB). The head space oxygen decreased significantly in CSB and slightly in PLA bags. Thickness of EO blended PLA composite was increased (99 μm), tensile strength (23.94 MPa), WVTR (1.42 g/m2.hr) analysis, significant folding ability, and swelling capacity (0.24 %) showed slight reduction in composite film. TGA showed good thermal stability (334˚C) and XRD displayed the increased crystallinity (38.35 %) in PLAOM films, SEM and FTIR analysis of the synthesized composite films revealed complete homogenization of EO and PLA matrix. In addition, SEM analysis of insects (control & treated) revealed less topology changes in the elytra. Biodegradability study confirmed the weight loss in PLA films. Hence, current approach of using composite EO's with PLA offers sustainable solution for prevention of infestation during storage of millets.

Predicted multispecies unintended effects from outdoor genome editing

CRISPR/Cas9, a potent genetic engineering tool widely adopted in agriculture, is capable of introducing new characteristics into plants on a large scale and without conventional breeding methods. Despite its remarkable efficiency, concerns have arisen regarding unintended consequences in uncontrolled environments. Our aim was to assess potential activity in organisms that could be exposed to genome editing in uncontrolled environments. We developed three scenarios, using irrigation, fumigation and fertilization as delivery methods, based on outdoor uses in agriculture, namely pest and disease control. Using publicly available software (Cas-OFFinder, NCBI Genome Data Viewer and STRING), off-target effects were predicted in multiple species commonly found in the agroecosystem, including humans (16 of 38 (42 %) sampled). Metabolic enrichment analysis (gene IDs), by connecting off-target genes into a physiological network, predicted effects on the development of nervous and respiratory systems. Our findings emphasize the importance of exercising caution when considering the use of this genome editing in uncontrolled environments. Unintended genomic alterations may occur in unintended organisms, underscoring the significance of understanding potential hazards and implementing safety measures to protect human health and the environment.

Life history correlations and trade-offs resulting from selection for dispersal in Tribolium castaneum

Dispersal is an important facet of the life history of many organisms and is, therefore, subject to selective pressure but does not evolve in isolation. Across nature, there are examples of dispersal syndromes and life history strategies in which suites of traits coevolve and covary with dispersal in combinations that serve to maximize fitness in a given ecological context. The red rust flour beetle, Tribolium castaneum, is a model organism and globally significant post-harvest pest that relies on dispersal to reach new patches of ephemeral habitat. Dispersal behaviour in Tribolium has a strong genetic basis. However, a robust understanding of the relationship between dispersal and other life-history components, which could elucidate evolutionary processes and allow pest managers to control their spread and reduce the impact of infestation, is currently lacking. Here, we use highly replicated lines of T. castaneum previously artificially selected for divergent small-scale dispersal propensity to robustly test several important life history components: reproductive strategy, development time, and longevity. As predicted, we find that a suite of important changes as a result of our selection on dispersal: high dispersal propensity is associated with a lower number of longer mating attempts by males, lower investment in early life reproduction by females, slower development of later-laid offspring, and longer female life span. These findings indicate that correlated intraspecific variation in dispersal and related traits may represent alternative life history strategies in T. castaneum. We therefore suggest that pest management efforts to mitigate the species' agro-economic impact should consider the eco-evolutionary dynamics within multiple life histories. The benefits of doing so could be felt both through improved targeting of efforts to reduce spread and also in forecasting how the selection pressures applied through pest management are likely to affect pest evolution.

Genetic architecture of dispersal behaviour in the post-harvest pest and model organism Tribolium castaneum

Dispersal behaviour is an important aspect of the life-history of animals. However, the genetic architecture of dispersal-related traits is often obscure or unknown, even in well studied species. Tribolium castaneum is a globally significant post-harvest pest and established model organism, yet studies of its dispersal have shown ambiguous results and the genetic basis of this behaviour remains unresolved. We combine experimental evolution and agent-based modelling to investigate the number of loci underlying dispersal in T. castaneum, and whether the trait is sex-linked. Our findings demonstrate rapid evolution of dispersal behaviour under selection. We find no evidence of sex-biases in the dispersal behaviour of the offspring of crosses, supporting an autosomal genetic basis of the trait. Moreover, simulated data approximates experimental data under simulated scenarios where the dispersal trait is controlled by one or few loci, but not many loci. Levels of dispersal in experimentally inbred lines, compared with simulations, indicate that a single locus model is not well supported. Taken together, these lines of evidence support an oligogenic architecture underlying dispersal in Tribolium castaneum. These results have implications for applied pest management and for our understanding of the evolution of dispersal in the coleoptera, the world's most species-rich order.

Farmers’ Perception of the Use and Benefits of Cowpea Storage Methods in Northern Ghana

Insect infestation during the storage of cowpea is a major challenge among smallholder farmers in sub-Saharan Africa (SSA). Farmers use various postharvest storage methods to deal with insect pests, including insecticides, which may result in health and environmental hazards. Four hundred (400) cowpea farmers were interviewed on their perceptions and preference of different storage methods in Northern Ghana. About 58% of farmers applied insecticides, 50% used ash, and 42% used hermetic triple-layer bags (Purdue Improved Crop Storage, PICS) to store cowpea. Most farmers (85.6%) preferred the PICS technology for its effectiveness (compared to insecticides, ash, and botanicals). Reasons for the non-use of PICS bags included unavailability (39.5%) and high price (11.7%). Farmers perceived that storing cowpea in PICS bags lowered pesticide-related health risks for both farmers and consumers. Thus, there is a need to improve the availability and affordability of PICS bags in Northern Ghana.

Management of stored grain pest with special reference to Callosobruchus maculatus, a major pest of cowpea: A review

Bruchids are most pernicious pest of stored grain pulses, especially in the tropical and subtropical areas. They penetrate into the fully grown matured pods, grains in fields and also during post-harvest storage. Among bruchids, Callosobruchus maculatus is the prominent pest having ubiquitous distribution. Chemical/synthetic insecticides provides adequate control against the C. maculatus on the pulses. However, the use of synthetic insecticides induces adverse health outcomes in agricultural workers and many causes various diseases such as cancers, genomic damage, oxidative stress, neurological disorders and respiratory, metabolic and thyroid effects. Therefore, alternative effective, safe and sustainable pest control, integration of different compatible methods should be taken into considerations. One of the possible managements might be use of traditional as well modern pest management practices. Traditional techniques include sealed containers, inert materials, harvesting time, alternate host, intercropping, storing un-threshed pulses, cleanliness, vegetable oil etc. Modern techniques such as temperature, freezing and heating, radiation treatments, resistance varieties, natural control, botanical extracts, chemical and microbial, transgenic approach, cold plasma treatments etc. thus integrated pest management might be alternative approach to combat the effect of pest. Therefore, present review aims to considers various measures for the handling of bruchids with special reference to Callosobruchus maculatus and integrated molecular inventions to decrease bruchids populations and enhance pulse productivity in pulses.

Tribolium beetles as a model system in evolution and ecology

Flour beetles of the genus Tribolium have been utilised as informative study systems for over a century and contributed to major advances across many fields. This review serves to highlight the significant historical contribution that Tribolium study systems have made to the fields of ecology and evolution, and to promote their use as contemporary research models. We review the broad range of studies employing Tribolium to make significant advances in ecology and evolution. We show that research using Tribolium beetles has contributed a substantial amount to evolutionary and ecological understanding, especially in the fields of population dynamics, reproduction and sexual selection, population and quantitative genetics, and behaviour, physiology and life history. We propose a number of future research opportunities using Tribolium, with particular focus on how their amenability to forward and reverse genetic manipulation may provide a valuable complement to other insect models.

Application of Ozone against the Larvae of Plodia interpunctella (Hübner) and Its Impacts on the Organoleptic Properties of Walnuts

ABSTRACT

One of the most important products grown in Iran is walnut (Juglans regia L.), but it can be threatened by storage pests such as insects. Ozonation is an environmentally friendly method for killing pest insects; accordingly, ozone efficacy in the control of a pest species of walnut, Indian meal moth (Plodia interpunctella (Hübner)), was assessed in this research. The selected walnut samples were infested with larvae of Indian meal moth and then subjected to various combinations of ozone concentration (3, 4.5, and 6 ppm) and exposure time (20, 30, 40, and 50 min). After exposure to the treatment combinations, larval mortality rates and changes to the sensory properties (color, taste, smell, crispness, stiffness, and overall acceptability), indicating consumer preference, of the walnuts were evaluated. Our results revealed enhanced mortality rates of P. interpunctella with an increase in both ozone concentration and exposure time: 99% mortality was recorded at the concentration and exposure time of 6 ppm and 50 min, respectively. Sensory assessments of the samples showed that ozone treatments had no significant impacts on the color, taste, crispness, stiffness, and overall acceptability of the product. Also, few changes were recorded for its smell, which could be improved over time after being exposed to the air. We conclude that application of higher ozone concentrations might provide acceptable levels of insect pest control for stored walnuts with no associated reduced trade-off for their quality attributes.

HIGHLIGHTS

Susceptibility of Alabama argillacea and Chrysodeixis includens (Lepidoptera: Noctuidae) larvae to Beauveria bassiana associated with kaolin

The mortality of the Alabama argillacea and Chrysodeixis includens (Lepidoptera: Noctuidae) larvae caused by the kaolin inert powder and the entomopathogenic fungus Beauveria bassiana were determined under laboratory conditions. Using the caterpillar submersion method, the CG 138 B. bassiana isolate was more pathogenic to A. argillacea than the CG 70, GC 82, ESALQ 634, and ESALQ 645. All five tested isolates caused similar mortality of C. includens. The mortality of first-instar larvae of A. argillacea and C. includens by feeding on leaf-disc impregnated with B. bassiana (CG 138) and kaolin was also determined. Higher A. argillacea mortalities were observed in the B. bassiana (CG 138) treatments, regardless of the presence of kaolin. However, the activity of kaolin + B. bassiana (CG 138) against C. includens was higher than each ingredient alone, indicating an additive action against C. includes larvae. The mortality of A. argillacea and C. includens larvae treated with kaolin + B. bassiana (CG 138) was similar, and the A. argillacea mortality was higher than that of C. includens with kaolin and B. bassiana (GC 138) separated. The treatment kaolin + B. bassiana (CG 138) is promising for the simultaneous management of these two defoliator pests, mainly A. includes. In addition, the monophagous A. argillacea is more susceptible to both kaolin and B. bassiana (GC 138) than the polyphagous C. includens, suggesting that the nutritional ecology plays an important role in the susceptibility of these defoliator species to alternative insecticides.

Effect of Diallyl Trisulfide on the Reproductive Behavior of the Grain Moth, Sitotroga cerealella (Lepidoptera: Gelechiidae)

The Angoumois grain moth, Sitotroga cerealella (Olivier, 1789) (Lepidoptera: Gelechiidae), is primarily a pest of stored products, that feeds inside the grain as larvae inducing significant economic loss in various stored commodities. Our previous studies proved that garlic essential oil and its active substances inhibit oviposition in moths. To further explore the effect on reproductive behavior and accurately interpret the results in terms of effective control of the moth population, moths were treated with diallyl trisulfide (DATS), an active substance of garlic essential oil, at a dose of 0.015 µL/L in air (LC₂₀, sub-lethal concentration). The results showed that fecundity and the proportion of viable eggs significantly decreased when the moths were treated with LC₂₀ DATS. Furthermore, female circadian mating rhythms and calling periodicity changed significantly after treatment. Compared with controls, the peak in mating occurred approximately 1 h earlier on the first day after DATS treatment, while it was significantly later on days 2 and 3. Moreover, mating frequency declined in presence of DATS compared with the controls. The percentage of females engaging in calling behavior decreased significantly with time, to less than 50%, 2 days after treatment, while a high calling percentage (>80%) was recorded for control moths on all 4 days. In addition, DATS had an inhibitory effect on the mating duration of S. cerealella. Moreover, a significant reduction was observed in the amount of sex pheromones extracted 8 h and 9 h after treatment. Our findings suggested that DATS has the potential to manipulate the moth population at LC₂₀ and would be an efficient alternative to synthetic insecticides for the control of pests having low toxicity to non-target organisms and ecosystems.

Habrobracon hebetor and Pteromalus cerealellae as Tools in Post-Harvest Integrated Pest Management

Consumers are increasingly demanding pesticide-free grain/legumes and processed foods. Additionally, there are more restrictions, or complete loss, of insecticides labelled for use in managing stored grain insects in post-harvest ecosystems. Suppression of post-harvest pests using parasitic wasps is a more sustainable alternative than chemical pesticides. Habrobracon hebetor (Say) (Hymenoptera: Braconidae) and Pteromalus cerealellae Ashmead (Hymenoptera: Pteromalidae) are two important parasitoids that limit economically important pests of stored products. Host searching ability and reproductive performances of H. hebetor and P. cerealellae depend on a wide range of factors, such as host species, commodities, and environmental conditions. Further, use of entomopathogens can complement the ability of parasitoids to regulate pest populations. This review provides information on aspects of H. hebetor and P. cerealellae biology and successful regulation of post-harvest pest populations.

New Insights into the Microbiota of Moth Pests

In recent years, next generation sequencing (NGS) technologies have helped to improve our understanding of the bacterial communities associated with insects, shedding light on their wide taxonomic and functional diversity. To date, little is known about the microbiota of lepidopterans, which includes some of the most damaging agricultural and forest pests worldwide. Studying their microbiota could help us better understand their ecology and offer insights into developing new pest control strategies. In this paper, we review the literature pertaining to the microbiota of lepidopterans with a focus on pests, and highlight potential recurrent patterns regarding microbiota structure and composition.

Application of Ozone to Control Dried Fig Pests-Oryzaephilus surinamensis (Coleoptera: Silvanidae) and Ephestia kuehniella (Lepidoptera: Pyralidae)-and Its Organoleptic Properties

Ozone is a powerful oxidant which can be used for killing insects and microorganisms. In this study, ozone was applied in the gaseous form to control two species of pests in stored dried figs. The samples of figs (50 g each) were infested with adults of Oryzaephilus surinamensis L. and larvae of Ephestia kuehniella Zeller and were subjected to different combinations of ozone concentrations (2, 3, and 5 ppm) and exposure times (15, 30, 45, 60, and 90 min). Changes in organoleptic properties (color, sweetness, firmness, aroma, and overall acceptability) during ozonation were studied. The results showed that the mortality rate increased with an increase in ozone concentration and exposure time. The total mortality of both pests was achieved at an ozone concentration of 5 ppm and exposure time of 90 min. Sensory evaluation showed that ozone only had a negligible effect on aroma. Therefore, the usage of ozone is recommended during the postharvest process instead of other chemical fumigants, such as methyl bromide and phosphine.

Microwave Heating as an Alternative Quarantine Method for Disinfestation of Stored Food Grains

Insects and pests constitute a major threat to food supplies all over the world. Some estimates put the loss of food grains because of infestation to about 40% of the world production. Contemporary disinfestation methods are chemical fumigation, ionizing radiation, controlled atmosphere, conventional hot air treatment, and dielectric heating, that is, radio frequency and microwave energy, and so forth. Though chemical fumigation is being used extensively in stored food grains, regulatory issues, insect resistance, and environmental concerns demand technically effective and environmentally sound quarantine methods. Recent studies have indicated that microwave treatment is a potential means of replacing other techniques because of selective heating, pollution free environment, equivalent or better quality retention, energy minimization, and so forth. The current paper reviews the recent advances in Microwave (MW) disinfestation of stored food products and its principle and experimental results from previous studies in order to establish the usefulness of this technology.