Pest Control Strategies Research Articles

Initial ingestion of CMV-infected plants reduces subsequent aphid performance

The tritrophic interactions among plant virus, host plants, and insect vectors directly influence the natural ecosystem, which, in turn, has tremendous practical implications in the sustainable pest control strategies. Cucumber mosaic virus (CMV), transmitted by aphids in a non-persistent manner, causes severe damage in diverse crops worldwide. There is a wealth of information on the initial round of interactions within this tritrophic system. However, knowledge on the subsequent round of interactions is very limited. In this research, we focused on their interactions among Nicotiana tabacum cv. Samsum plants, CMV, and green peach aphids, Myzus persicae specifically after the initial round of aphid feeding on CMV-infected plants. Our results show that initial aphid feeding on CMV-infected plants reduces the fitness of the subsequent aphids. The reproduction capacity, longevity, and survival rate of M. persicae are reduced on CMV-infected plants, previously foraged by M. persicae. Furthermore, the initial aphid feeding on CMV-infected plants induce gene expression involved in the salicylic acid (SA) signaling pathway and suppresses the expression of downstream genes associated with jasmonic acid (JA) signaling pathway. Besides, plant chlorophyll content and nitrogen source are reduced on those CMV-infected plants, previously foraged by aphids. The negative impacts on the fitness and performance of the subsequent aphids may have significant implications in virus transmission, distribution, and epidemiology.

Regulatory Mechanisms of Vitellogenesis in Insects.

Vitellogenesis is pre-requisite to insect egg production and embryonic development after oviposition. During insect vitellogenesis, the yolk protein precursor vitellogenin (Vg) is mainly synthesized in the fat body, transported by the hemolymph through the intercellular spaces (known as patency) in the follicular epithelium to reach the membrane of maturing oocytes, and sequestered into the maturing oocytes via receptor-mediated endocytosis. Insect vitellogenesis is governed by two critical hormones, the sesquiterpenoid juvenile hormone (JH) and the ecdysteriod 20-hydroxyecdysone (20E). JH acts as the principal gonadotropic hormone to stimulate vitellogenesis in basal hemimetabolous and most holometabolous insects. 20E is critical for vitellogenesis in some hymenopterans, lepidopterans and dipterans. Furthermore, microRNA (miRNA) and nutritional (amino acid/Target of Rapamycin and insulin) pathways interplay with JH and 20E signaling cascades to control insect vitellogenesis. Revealing the regulatory mechanisms underlying insect vitellogenesis is critical for understanding insect reproduction and helpful for developing new strategies of insect pest control. Here, we outline the recent research progress in the molecular action of gonadotropic JH and 20E along with the role of miRNA and nutritional sensor in regulating insect vitellogenesis. We highlight the advancements in the regulatory mechanisms of insect vitellogenesis by the coordination of hormone, miRNA and nutritional signaling pathways.

Moderately decreasing fertilizer in fields does not reduce populations of cereal aphids but maximizes fitness of parasitoids

Examination of the tradeoff between the extent of decreasing nitrogen input and pest suppression is crucial for maintaining the balance between essential yield and an efficient, sustainable pest control strategy. In this study, an experiment with four manipulated nitrogen fertilizer levels (70, 140, 210, and 280 kg N ha−1 = conventional level) was conducted to explore the effects of decreasing nitrogen on cereal aphids (Sitobion avenae and Rhopalosiphum padi) (Hemiptera: Aphididae), Aphidiinae parasitoids (Hymenoptera: Braconidae: Aphidiinae), and body sizes of parasitoids. The results indicated that nitrogen application, in the range of 70–280 kg N ha−1, has the potential to impact the populations of cereal aphids and their parasitoids. However, both differences between densities of cereal aphids and their parasitoids in moderate (140–210 kg N ha−1) and those in high nitrogen input (280 kg N ha−1) were not significant, and the parasitism rate was also unaffected. A higher parasitism rate reduced population growth of the cereal aphid (S. avenae). Additionally, a moderate decrease of nitrogen fertilizer from 280 to 140–210 kg N ha−1 maximized the body sizes of Aphidiinae parasitoids, indicating that a moderate decrease of nitrogen fertilizer could facilitate biocontrol of cereal aphid by parasitoids in the near future. We conclude that a moderate decrease in nitrogen application, from 280 to 140–210 kg N ha−1, does not quantitatively impact the densities of cereal aphids or the parasitism rate but can qualitatively maximize the fitness of the parasitoids.

Silencing of Double-Stranded Ribonuclease Improves Oral RNAi Efficacy in Southern Green Stinkbug Nezaraviridula.

Variability in RNA-interference (RNAi) efficacy among different insect orders poses a big hurdle in the development of RNAi-based pest control strategies. The activity of double-stranded ribonucleases (dsRNases) in the digestive canal of insects can be one of the critical factors affecting oral RNAi efficacy. Here, the involvement of these dsRNases in the southern green stinkbug Nezaraviridula was investigated. First, the full sequence of the only dsRNase (NvdsRNase) in the transcriptome of N. viridula was obtained, followed by an oral feeding bioassay to evaluate the effect of NvdsRNase-silencing on oral RNAi efficacy. The NvdsRNase was first silenced in nymphs by NvdsRNase-dsRNA injections, followed by exposure to an artificial diet containing a lethal αCop-specific dsRNA. A significantly higher mortality was observed in the NvdsRNase-silenced nymphs when placed on the dsαCop-containing diet (65%) than in the dsGFP injected and dsαCop fed control (46.67%). Additionally, an ex vivo dsRNA degradation assay showed a higher stability of dsRNA in the saliva and midgut juice of NvdsRNase-silenced adults. These results provide evidence for the involvement of NvdsRNase in the reduction of oral RNAi efficacy in N. viridula. This information will be useful in further improving potential RNAi-based strategies to control this pest.

Minimizing Honey Bee Exposure to Pesticides


 
 
 
 
 
 
 To safely solve a pest problem, growers and pesticide applicators must be aware of the potential impacts of some pest-control strategies on bees, other pollinators, and beneficial arthropods. This 14-page fact sheet written by J. D. Ellis, J. Klopchin, E. Buss, and others and published by the UF/IFAS Entomology and Nematology Department explains the issue and provides strategies to protect honey bees and other beneficial insects from pesticides. https://edis.ifas.ufl.edu/in1027
 
 
 
 
 
 

Intron-assisted, viroid-based production of insecticidal circular double-stranded RNA in Escherichia coli

ABSTRACT RNA interference (RNAi) is a natural mechanism for protecting against harmful genetic elements and regulating gene expression, which can be artificially triggered by the delivery of homologous double-stranded RNA (dsRNA). This mechanism can be exploited as a highly specific and environmentally friendly pest control strategy. To this aim, systems for producing large amounts of recombinant dsRNA are necessary. We describe a system to efficiently produce large amounts of circular dsRNA in Escherichia coli and demonstrate the efficient insecticidal activity of these molecules against Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte), a highly damaging pest of corn crops. In our system, the two strands of the dsRNA are expressed in E. coli embedded within the very stable scaffold of Eggplant latent viroid (ELVd), a small circular non-coding RNA. Stability in E. coli of the corresponding plasmids with long inverted repeats was achieved by using a cDNA coding for a group-I autocatalytic intron from Tetrahymena thermophila as a spacer. RNA circularization and large-scale accumulation in E. coli cells was facilitated by co-expression of eggplant tRNA ligase, the enzyme that ligates ELVd during replication in the host plant. The inserted intron efficiently self-spliced from the RNA product during transcription. Circular RNAs containing a dsRNA moiety homologous to smooth septate junction 1 (DvSSJ1) gene exhibited excellent insecticide activity against WCR larvae. Finally, we show that the viroid scaffold can be separated from the final circular dsRNA product using a second T. thermophila self-splicing intron in a permuted form.

Predicting the Presence of Leptospires in Rodents from Environmental Indicators Opens Up Opportunities for Environmental Monitoring of Human Leptospirosis

Leptospirosis, an environmental infectious disease of bacterial origin, is the infectious disease with the highest associated mortality in Seychelles. In small island territories, the occurrence of the disease is spatially heterogeneous and a better understanding of the environmental factors that contribute to the presence of the bacteria would help implement targeted control. The present study aimed at identifying the main environmental parameters correlated with animal reservoirs distribution and Leptospira infection in order to delineate habitats with highest prevalence. We used a previously published dataset produced from a large collection of rodents trapped during the dry and wet seasons in most habitats of Mahé, the main island of Seychelles. A land use/land cover analysis was realized in order to describe the various environments using SPOT-5 images by remote sensing (object-based image analysis). At each sampling site, landscape indices were calculated and combined with other geographical parameters together with rainfall records to be used in a multivariate statistical analysis. Several environmental factors were found to be associated with the carriage of leptospires in Rattus rattus and Rattus norvegicus, namely low elevations, fragmented landscapes, the proximity of urbanized areas, an increased distance from forests and, above all, increased precipitation in the three months preceding trapping. The analysis indicated that Leptospira renal carriage could be predicted using the species identification and a description of landscape fragmentation and rainfall, with infection prevalence being positively correlated with these two environmental variables. This model may help decision makers in implementing policies affecting urban landscapes and/or in balancing conservation efforts when designing pest control strategies that should also aim at reducing human contact with Leptospira-laden rats while limiting their impact on the autochthonous fauna.

Integration of dsRNA against host immune response genes augments the virulence of transgenic Metarhizium robertsii strains in insect pest species.

SummaryThe slow lethality of fungal biopesticides to insects restrains their widespread application as a strategy of pest control. In this study, unary, binary and ternary transgenic Metarhizium robertsii were created by integrating genes that encode the scorpion neurotoxin BjαIT, the cuticle‐degrading protease Pr1A, and a double‐stranded RNA (dsRNA) that targets host gnbp3, individually or collectively under a constitutive promoter to enhance virulence. Compared with the parental wild type, all unary transgenic strains had increased virulence against four insect species, Tenebrio molitor, Locusta migratoria, Plutella xylostella and Galleria mellonella, whereas the binary transgenic strain expressing both pr1A and BjαIT had increased virulence to T. molitor and L. migratoria, with no change in virulence against P. xylostella and G. mellonella. Importantly, all ternary transgenic strains simultaneously expressing pr1A, BjαIT, and the dsRNA specific to host gnbp3 exhibited the highest increase in insect‐specific virulence. This finding highlights a novel strategy for genetic engineering of dsRNAs that target genes associated with the host immune response alongside virulence genes to maximize fungal virulence and lethality against insect pests.

Intercropping Rosemary (Rosmarinus officinalis) with Sweet Pepper (Capsicum annum) Reduces Major Pest Population Densities without Impacting Natural Enemy Populations.

Simple SummaryDue to the harmful effects of pesticides on the environment and human health, alternative control methods have become more favored in vegetable pest management. Intercropping and natural enemy release are two widely implemented environmentally friendly control methods. In this study, the impact of sweet pepper/rosemary intercropping on pest population suppression was evaluated under greenhouse conditions and the effect of rosemary intercropping on natural enemy population dynamics was investigated. The results showed that intercropping rosemary with sweet pepper significantly reduced the population densities of three major pest species on sweet pepper, Frankliniella intonsa, Myzus persicae, and Bemisia tabaci, but did not affect the population densities of released natural enemies, predatory bug Orius sauteri, and parasitoid Encarsia formosa. Significant pest population suppression with no adverse effect on released natural enemy populations in the sweet pepper/rosemary intercropping system suggests this could be an approach for integrated pest management of greenhouse-cultivated sweet pepper.Intercropping of aromatic plants provides an environmentally benign route to reducing pest damage in agroecosystems. However, the effect of intercropping on natural enemies, another element which may be vital to the success of an integrated pest management approach, varies in different intercropping systems. Rosemary, Rosmarinus officinalis L. (Lamiaceae), has been reported to be repellent to many insect species. In this study, the impact of sweet pepper/rosemary intercropping on pest population suppression was evaluated under greenhouse conditions and the effect of rosemary intercropping on natural enemy population dynamics was investigated. The results showed that intercropping rosemary with sweet pepper significantly reduced the population densities of three major pest species on sweet pepper, Frankliniella intonsa, Myzus persicae, and Bemisia tabaci, but did not affect the population densities of their natural enemies, the predatory bug, Orius sauteri, or parasitoid, Encarsia formosa. Significant pest population suppression with no adverse effect on released natural enemy populations in the sweet pepper/rosemary intercropping system suggests this could be an approach for integrated pest management of greenhouse-cultivated sweet pepper. Our results highlight the potential of the integration of alternative pest control strategies to optimize sustainable pest control.

Gambling in the garden: Pesticide use and risk exposure in Ugandan smallholder farming

The use and promotion of pesticides is on the increase in many sub-Saharan African countries, including in the smallholder sector. This paper stems from placed-based research in Uganda and aims at advancing current knowledge on smallholder farmers' motivations for pesticide use, the extent and character of such use, as well as on lived experiences regarding the impacts of pesticides. Data was generated through a household survey, in-depth interviews and focus group discussions with farmers, complemented by field observations and interviews with local agricultural actors. Conceptually, we draw on political ecology to link local practice to broader conditions and processes and their social-environmental outcomes. Our findings demonstrate that a large majority of farmers have resorted to pesticides as their primary strategy for pest control. Current practices entail substantial human health and environmental risks which tend to be socially differentiated, including along gender lines. Many farmers are concerned about the impacts and uncertainties surrounding pesticides, but face numerous barriers to behavioral change. While intensifying pest pressure is one such immediate barrier, our findings also suggest that deep structural forces shape farmers' adoption of pesticides and prevent adequate protective measures. Rapid market liberalization combined with poor regulation enforcement have resulted in widespread promotion of agro-chemicals and a large informal market for cheap, poor-quality products, including counterfeits. Low public spending on the agricultural sector, a malfunctioning extension system and systematic lack of development and promotion of strategies not centered on synthetic pesticides furthermore severely constrain farmers’ access to support on, and indeed options for, pest control. This lacking capacity and effort to adequately protect smallholders from pesticide exposure and ensure their ability to make informed decisions on pest management clearly places the burden of risk disproportionately on an already vulnerable group.

Behavioural response of the fungus gnat, Bradysia impatiens (Diptera: Sciaridae) towards certain edible mushrooms and saprophytic fungi

AbstractThe fungus gnat Bradysia impatiens (Johannsen) is a worldwide pest inhabiting organic‐rich environments, including mushroom‐cultivation substrates, which leads to massive production losses of edible mushrooms. To promote a non‐insecticidal pest control strategy, we evaluated adult behavioural response towards two saprophytic fungal strains Aspergillus flavus Link and Mucor circinelloides Tiegh., isolated from B. impatiens‐inhabiting substrates and six edible mushrooms species. Our results indicated that (a) B. impatiens was most attracted to the oyster mushroom Pleurotus ostreatus among all six edible mushrooms; (b) males and females demonstrated a significant attraction for M. circinelloides over A. flavus and P. ostreatus; (c) adults demonstrated dynamic attraction tendencies that varied with the culture periods of A. flavus and M. circinelloides, wherein females represented most (mean = 78.6%) of the attracted individuals; and (d) larvae that fed on mycelial cultures of M. circinelloides could complete their entire life cycles, but larvae could not survive on a non‐fungal or A. flavus diet. These results demonstrate the potential for the development of M. circinelloides in a push‐pull strategy to biocontrol this pest in edible mushroom cultivation.

Landscape-dependent effects of varietal mixtures on insect pest control and implications for farmer profits.

Intraspecific plant diversity can significantly impact insect herbivore populations in natural systems. Yet, its role as an insect pest control strategy in agriculture has received less attention, and little is known about which crop traits are important to herbivores in different landscape contexts. Moreover, empirical economic analyses on the cost‐effectiveness of varietal mixtures are lacking. We used varietal mixtures of Brassica oleracea crops on working farms to examine how two metrics of intraspecific crop diversity, varietal richness and number of plant colors (color richness), affect crop damage and the incidence and abundance of two insect pest species: Pieris rapae and Phyllotreta spp. We evaluated the context‐dependency of varietal mixtures by sampling early‐ and late‐season plantings of B. oleracea crops in farms across a gradient of landscape composition. We developed crop budgets and used a net present value analysis to assess the impact of varietal mixtures on input and labor costs, crop revenues, and profit. We found context‐dependent effects of varietal mixtures on both pests. In early‐season plantings, color richness did not affect Phyllotreta spp. populations. However, increasing varietal richness reduced Phyllotreta spp. incidence in simple landscapes dominated by cropland, but this trend was reversed in complex landscapes dominated by natural habitats. In late‐season plantings, color richness reduced the incidence and abundance of P. rapae larvae, but only in complex landscapes where their populations were highest. Varietal richness had the same effect on P. rapae larvae as color richness. Unexpectedly, we consistently found lower pest pressure and reduced crop damage in simple landscapes. Although varietal mixtures did not affect crop damage, increasing color richness corresponded with increased profits, due to increased revenue and a marginal reduction in labor and input costs. We demonstrate varietal mixtures can significantly impact pest populations, and this effect can be mediated by intraspecific variation in crop color. However, the strength and direction of these effects vary by season, landscape composition, and pest species. The association between varietal color richness and profitability indicates farmers could design mixtures to enhance economic returns. We recommend additional research on the benefits of intraspecific trait variation for farmers.

OBP2 in the Midlegs of the Male Bactrocera dorsalis Is Involved in the Perception of the Female-Biased Sex Pheromone 4-Allyl-2,6-dimethoxyphenol.

Short-range semiochemicals convey individual-specific information, which is important for final successful courtship and copulation. In this study, an electroantennography (EAG) instrument was used to determine the legs of male Bactrocera dorsalis that might participate in the perception of 4-allyl-2,6-dimethoxyphenol (4-DMP), a female-biased cuticular hydrocarbon (CHC) component. By performing comparative RNA-seq analysis, nine differentially expressed OBPs between 4-DMP-stimulated (M4-DMP) and unstimulated (M) male flies were screened out. Among the four downregulated OBPs, BdorOBP2 exhibited the strongest binding to 4-DMP than BdorOBP4, BdorOBP19a, and BdorOBP56h. Functional analyses confirmed that the reduction in transcript abundance of BdorOBP2 led to a significant decrease in behavioral responses of male flies to 4-DMP. In silico simulation revealed dramatic changes in the key residues and conformation between the two complexes, implying that BdorOBP2 might activate different receptors after binding to 4-DMP or methyl eugenol (ME). The results of this study suggest that BdorOBP2 mediates behavioral responses to 4-DMP and could be a promising molecular target for strategies of pest control.

Green Copper Nano-Pesticide Synthesized by Using Annona Squamosa L., Seed and their Efficacy on Insect Pest as well as Non-Target Species

Insect pest resistance challenge to existing classes of insecticides is jeopardizing the currently attained achievements in pests control for the public health and economy worldwide. Alternative pesticides with different mode of action are of paramount importance. The pesticidal efficacy of Annona squamosa L. seed derived green copper nanoparticles (CuNPs) against Anopheles stephensi, Tenebrio molitor and non-targeting organism Artemia nauplii at 24h post treatment at laboratory condition was conducted. A. squamosa L., seed derived cupper nanoparticles were characterized through, UV-vis spectrophotometer, FT-IR, XRD, and EDaX, HR-SEM, TEM and AFM analysis. Insect larvae were exposed to discriminating dosage of 170μg/ml deliver significant mortality rate comparable to other concentrations against An. stephensi and T. molitor. The synthesis CuNPs lower toxicity was observed on non-targeting organism A. nauplii. The present study suggests this bio-rational green copper nano-pesticide from A. squamosa L., seed displays a significant effect to reduce the larvae of insect pest and lower toxicity to beneficial organism. These results suggest that, use of A. squamosa L., seed derived CuNPs is a rapid, environmentally safer, and greener approach for insect control. This could lead to a new avenue in pest control strategy.

Fauna Pests Infesting Pepper (<i>Piper nigrum</i> L.) in Penja-Cameroon

Pepper is one of the spices used in the fight against covid-19 in Cameroon. But its production faces many constraints, including arthropods and Molluscs. The purpose of this study in the Penja production basin was to invent the fauna associated with pepper and support trees, as well as pest damage for the development of an appropriate control program. To achieve this, a weekly fauna collection was conducted in 2020 on Lonpomg and Muntok pepper varieties and pest damage was identified. The individuals were captured using an entomological net and a mouth aspirator or with the hand and identified at the Phytopathology and Agricultural Zoology Research Unit, University of Dschang. The identification of this fauna was done under a binocular magnifying glass using the available identification keys. A total of 278 Insecta and Gastropoda were captured. The Insecta class consists of 9 orders (Coleoptera, Diptera, Hemiptera, Hymenoptera, Isoptera, Lepidoptera, Odonata, Orthoptera and Phasmatodea), and the order of Stylommatophora. Orthoptera was more representative in terms of individuals (85) and Isoptera and Odonata, the least representative (01 individual). Lonpomg variety was found to be the most attractive to pests. Fauna of useful insects is counted in Hymenoptera, others being pests. The presence of these useful insects shows that biological control is possible. The data collected provide a basis for preliminary knowledge of Piper nigrum's fauna and should be taken into consideration in the design of integrated control strategies for pepper pests in Cameroon.

Silver nanoparticles loaded pyrrole based pesticidal metabolites (AgNps-PFM) nanoconjugate induced impact on the gut microbion and immune response against lepidopteron pest Spodoptera litura (Fab.)

Pest control measures using nanobiotechnology principles is now being extensively utilized in the various parts of the world. Understanding the molecular mechanism behind the pestiicdal activity of the nanomaterials is essential to exploit the principles of nanomaterials as an effective pest control strategy. In the present investigation, impact of the nanoconjugate prepared from biogenic silver nanoparticles-fungal based insecticidal metabolites (AgNps-FM) on the gut microbion and immune response against major lepidopteron pest Spodoptera litura (Fab.) was studied. Nanoconjugate was prepared from silver nanoparticles from Pomegranate (Punica granatum) peel extract with the fungal based pesticidal metabolites. Highly stable nano structural nano conjugate thus obtained was evaluated against gut microbion and immune response of Spodoptera litura. Gut microbion status was studied by determination of microbial count, extra cellular enzymes potential of the gut microbial isolates adopting culture dependent methods. Nanoconjugate induced effect on the immune response was done by recording total hemocyte count and reduced total haemocyte count, phenol oxidase activity and lectin expression pattern Synthesized nanoconjugate brought about notable impact on the gut microbion count and their extra cellular enzyme potential. Reduced haemocytes count, poor lectin expression and reduced phenol oxidase production reveals the immune suppressive activity. High efficacy of the Nanoconjugate thus obtained would suggest the possible utilization of Nanoconjugate as an effective, safe pesticidal agent against economic important insect pests.

Fitness and mating compatibility of Chrysodeixis includens (W.) (Lepidoptera: Noctuidae) populations collected in different provinces and crops in Argentina.

Chrysodeixis includens, is an important Plusiinae pest that feeds on soybean, beans, and cotton. This species has a genetic structure determined by molecular markers in populations collected in soybean crops in Brazil and has developed resistance to insecticides. This had led to an increased interest in the genetic diversity of its populations in Argentina. This study aimed to characterize the fitness parameters and mating compatibility of geographically distant C. includens populations and on different host plants in Argentina. Intra- and inter-population crosses revealed that C. includens populations from Tucumán and Santiago del Estero provinces did not present any evidence of prezygotic and postzygotic incompatibilities, suggesting that both populations collected from soybean plants belonged to a single wide-ranging species. Prezygotic and postzygotic incompatibilities were detected between populations collected from different crops (soybean and bean). These incompatibilities may be caused by the different nutrients that each plant species renders, or the specific pest control strategies which may affect C. includens behavior. Studies of the genetic structure of C. includens populations based on mating isolation on other crops, as well as of the impact of management strategies on the specie, will increase understanding of the reproductive compatibility revealed by the present study.

Evaluation of The Diversity of Durum Wheat Coleoptera (Triticum Durum Desf.) in the Region of Sigus Oum El Bouaghi (Eastern Algeria)

The Oum El Bouaghi region in Eastern Algeria, long considered as a cereal-growing area is nowadays a durum wheat production region par excellence. Although the damage caused by Coleoptera is very significant, studies on the knowledge of their diversity are few and remain limited for some entomological groups. Our work is the first step to evaluate the diversity of Coleoptera and the long-term impact of taking biological management measures against harmful fauna in favour of more environment friendly agriculture. To assess the beetle community, different sampling methods were combined (Barber trap, coloured traps, mowing net and sight hunting). Evaluation of the results of a single campaign showed that Coleoptera infested with durum wheat vary in abundance and diversity. We identified more than 100 species of Coleoptera belonging to 22 different families for a total number of 5698 individuals belonging mainly to the Carabidae, Curculionidae, Chrysomelidae, Scarabidae and Staphylinidae families. Although the majority of Coleoptera collected are pests of durum wheat crops (47.57%) the case of Tropinota hirta, Notaris sp or Oulema melanopus in particular, there was an interesting presence of predators (28.15%) the case of Carabidae or Staphylinidae in particular even with low relative abundance. The temporal evolution of the Coleoptera showed that the species diversity indicated a peak of abundance at the full tillering stage following an accentuated vegetative development of the host plant, and the presence of weeds. The data collected in this way constitute a basis for a preliminary knowledge of the durum wheat Coleoptera and can thus be used to design pest control strategies.

Efficacy of Partially Purified Soybean Protease Inhibitor on The Development of Cotton Leafworm, Spodoptera littoralis (Bosid.)

Plant protease inhibitors) PIs) are one of the plant strategies to maintain favorable growth and survival. Soybean trypsin inhibitor is the most well-known of the plant serine proteinase. The present study aims to detect the inhibitory activity of two concentrations of partially purified trypsin inhibitors from seeds of soybean(Glycine max). Comparing the results of feeding larvae on partially purified soybean inhibitors with control, revealed that the larval weight reduction caused by soybean PI was noticed after seven days of treatment. The highest larval weight reduction was obtained due to treatment with SPI at levels SPI 30% and SPI 60%, and there was no significant difference between the two levels. Feeding larvae on SPI 60% caused higher larval mortality about 20% than the control followed by SPI 30% which caused 16% larval mortality. The pupation in treated larvae was delayed two days by comparing to control. The highest weight reduction in pupal weight was 3.5± 0.3 gm at SPI 60% compared with control. Besides, the pupation rate decreased from 83% at SPI 60% to 80% at SPI 30%. Also, the reduction in adult emergency % was recorded at SPI level 30% by 41% and at SPI level 60% by 16% compared with the control. Results reveal that soybean protease inhibitors inhibit the growth and development of S. littoralis, and may be used in integrated pest control strategies.

Computational approach to explore the inhibitory potential of biologically derived compounds against Spodoptera litura vitellogenin receptor (VgR) using structure based virtual screening and molecular dynamics

In the everlasting combat against the pests of agricultural importance, it is essential to come up with a novel strategy for pest control. This can be achieved through understanding the insect pest at cellular and molecular levels. Vitellogenin (Vg) and vitellogenin receptor (VgR) are essential for successful reproduction in insect. The N-terminal Ligand Binding Domain (LBD) of VgR is responsible for the transportation of vital protein (Vg) to the developing oocyte through receptor mediated endocytosis pathway. This can be implemented to various predicaments and betterments for exploitation in pest management, in a target specific and eco-friendly manner. For this, natural metabolites isolated from various biological sources were used as ligand. The purpose of this study was to analyze the inhibitory potential of 14 biologically derived compounds against N-terminal (Ligand Binding Repeats) LBRs of S. litura by computational docking. 3 D structure of LBRs of S. litura was generated by Raptor X software and the structure was refined and validated. The validated structure was docked using autodock vina. Docking results revealed that spinosyn A and milbemycin A4 have inhibitory activity against VgR. Molecular dynamics (MD) simulation confirms the stable binding of the ligand. From the above results, spinosyn A and milbemycin A4 may be exploited for the pest management. Communicated by Ramaswamy H. Sarma