Control Of Insect Pests Research Articles

Improved YOLOv8 and SAHI Model for the Collaborative Detection of Small Targets at the Micro Scale: A Case Study of Pest Detection in Tea

Pest target identification in agricultural production environments is challenging due to the dense distribution, small size, and high density of pests. Additionally, changeable environmental lighting and complex backgrounds further complicate the detection process. This study focuses on enhancing the recognition performance of tea pests by introducing a lightweight pest image recognition model based on the improved YOLOv8 architecture. First, slicing-aided fine-tuning and slicing-aided hyper inference (SAHI) are proposed to partition input images for enhanced model performance on low-resolution images and small-target detection. Then, based on an ELAN, a generalized efficient layer aggregation network (GELAN) is designed to replace the C2f module in the backbone network, enhance its feature extraction ability, and construct a lightweight model. Additionally, the MS structure is integrated into the neck network of YOLOv8 for feature fusion, enhancing the extraction of fine-grained and coarse-grained semantic information. Furthermore, the BiFormer attention mechanism, based on the Transformer architecture, is introduced to amplify target characteristics of tea pests. Finally, the inner-MPDIoU, based on auxiliary borders, is utilized as a replacement for the original loss function to enhance its learning capacity for complex pest samples. Our experimental results demonstrate that the enhanced YOLOv8 model achieves a precision of 96.32% and a recall of 97.95%, surpassing those of the original YOLOv8 model. Moreover, it attains an mAP@50 score of 98.17%. Compared to Faster R-CNN, SSD, YOLOv5, YOLOv7, and YOLOv8, its average accuracy is 17.04, 11.23, 5.78, 3.75, and 2.71 percentage points higher, respectively. The overall performance of YOLOv8 outperforms that of current mainstream detection models, with a detection speed of 95 FPS. This model effectively balances lightweight design with high accuracy and speed in detecting small targets such as tea pests. It can serve as a valuable reference for the identification and classification of various insect pests in tea gardens within complex production environments, effectively addressing practical application needs and offering guidance for the future monitoring and scientific control of tea insect pests.

Tripartite interactions of an endophytic entomopathogenic fungus, Asian corn borer, and host maize under elevated carbon dioxide.

Biological control of insect pests is encountering an unprecedented challenge in agricultural systems due to the ongoing rise in carbon dioxide (CO2) level. The use of entomopathogenic fungi (EPF) in these systems is gaining increased attention, and EPF as crop endophytes hold the potential for combining insect pest control and yield enhancement of crops, but the effects of increased CO2 concentration on this interaction are poorly understood. Here, the introduction of endophytic EPF was explored as an alternative sustainable management strategy benefiting crops under elevated CO2, using maize (Zea mays), Asian corn borer (Ostrinia furnacalis), and EPF (Beauveria bassiana) to test changes in damage to maize plants from O. furnacalis, and the nutritional status (content of carbon, nitrogen, phosphorus, potassium), biomass, and yield of maize. The results showed that endophytic B. bassiana could alleviate the damage caused by O. furnacalis larvae for maize plants under ambient CO2 concentration, and this effect was enhanced under higher CO2 concentration. Inoculation with B. bassiana effectively counteracted the adverse impact of elevated CO2 on maize plants by preserving the nitrogen content at its baseline level (comparable with ambient CO2 conditions without B. bassiana). Both simultaneous effects could explain the improvement of biomass and yield of maize under B. bassiana inoculation and elevated CO2. This finding provides key information about the multifaceted benefits of B. bassiana as a maize endophyte. Our results highlight the promising potential of incorporating EPF as endophytes into integrated pest management strategies, particularly under elevated CO2 concentrations. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Pan-Genome Analysis and Secondary Metabolic Pathway Mining of Biocontrol Bacterium Brevibacillus brevis

Brevibacillus brevis is one of the most common biocontrol strains with broad applications in the prevention and control of plant diseases and insect pests. In order to deepen our understanding of B. brevis genomes, describe their characteristics comprehensively, and mine secondary metabolites, we retrieved the genomic sequences of nine B. brevis strains that had been assembled into complete genomes from the NCBI database. These genomic sequences were analyzed using phylogenetic analysis software, pan-genome analysis software, and secondary metabolite mining software. Results revealed that the genome size of B. brevis strains ranged from 6.16 to 6.73 Mb, with GC content ranging from 47.0% to 54.0%. Phylogenetic analysis classified the nine B. brevis strains into three branches. The analyses of ANI and dDDH showed that B. brevis NEB573 had the potential to become a new species of Brevibacillus and needed further research in the future. The pan-genome analysis identified 10032 gene families, including 3257 core gene families, 3112 accessory gene families, and 3663 unique gene families. In addition, 123 secondary metabolite biosynthetic gene clusters of 20 classes were identified in the genomes of nine B. brevis strains. The major types of biosynthetic gene clusters were non-ribosomal peptide synthase (NRPS) and transAT polyketide synthase (transAT-PKS). Furthermore, a large number of untapped secondary metabolites were identified in B. brevis. In summary, this study elucidated the pan-genome characteristics of the biocontrol bacterium B. brevis and identified its secondary metabolites, providing valuable insights for its further development and utilization.

Assessment of Safe Vegetable Cultivation at Jashore in Bangladesh: Evidence from Country Bean, Cucumber and Pointed Gourd Cultivation

The study was designed to assess the present status and methods of safe vegetable production at farm level in selected areas of Jashore during January-May, 2023. For the study ninety sample farmer were selected by stratified sampling from three sub-district of Jashore. Average farm size was 0.79 ha in study area. Farmer doing different agronomic management such as weeding, irrigation, spraying, de-topping, stalking, earthing up etc. Farmer used different methods simultaneously such as insecticide spray, bio-pesticide, sex pheromone, yellow trap, white trap, hand picking etc. for controlling insect pest. About sixty-four percent farmer sprayed synthetic pesticide and rest of them used bio control method such as bio-pesticide (bio-chamak, eco-mac, bio-envir, bio-cin), sex pheromone trap, yellow trap and hand picking for control insect pest in their fields. About fifty-eight percent farmer used bio-fertilizer along with organic fertilizer (manure, vermin compost) and seventy-eight percent farmer used chemical fertilizer for vegetable cultivation. Total production cost of country bean was Tk.3,36,579 ha-1, cucumber was Tk.3,25,915 ha-1 and pointed gourd was Tk.4,40,106 ha-1. Among the cost item labor cost was highest. Average yield of country bean was 30.60 tha-1, cucumber was 30.08 tha-1 and pointed gourd was 41.60 tha-1. Highest benefit cost ratio was cucumber (2.13) followed by pointed gourd (2.07) and country bean (1.50), that means safe vegetable cultivation also profitable. Farmer awareness, havoc attack of pest and insect were the main problem for safe vegetable cultivation. Market facilities, demand, value chain, proper price for organic vegetable, and farmer motivation can promote and enhance safe vegetable cultivation.

Effect of faba bean nectar on longevity and fecundity of Plutella xylostella and its parasitoid Cotesia vestalis

Intercropping faba bean with vegetables provides a possibility to promote pest control and better nutrient cycling in sustainable agriculture. Faba bean produces extrafloral nectar which supports parasitoid wasps that play a role in the biological control of pest insects. However, adult lepidopteran pests also benefit from nectar, increasing their lifespan and the number of offspring they produce. Here, a laboratory-based study was conducted to assess the role of faba bean on the components of a Brassica-based host-parasitoid system. We measured how access to faba bean affected the longevity and fecundity of the brassica pest Plutella xylostella and its parasitoid Cotesia vestalis. It was also studied if odors of flowering faba bean disrupt host finding by C. vestalis in Y-tube bioassays and volatile organic compounds were analyzed to explain the olfaction-based choices made by the parasitoids. The longevity of C. vestalis was 6.6 times longer and the number of pupae produced almost 10 times greater when they had access to faba bean. Meanwhile, the longevity of P. xylostella was 3.6 times longer and it laid 4.6 times more eggs when provided access to faba bean. In Y-tube bioassays, C. vestalis females also oriented toward host-related odors of the damaged cabbage more than intact cabbage when odors of faba bean were mixed with both of them. In conclusion, faba bean provided sustenance to both pest insects and their natural enemies that prolonged their lifespans and their reproductive capacity.

Evaluation of the performance of maize storage facilities for control of storage insect pests in Ethiopia

Maize plays a vital role in Ethiopia's food security, supporting the lives of millions of people. However, postharvest grain deterioration due to insect infestation is a significant issue. To address this and improve food availability, reducing storage losses is essential. The experiments were carried out in both indoor and outdoor settings, where the indoor experiment evaluated the effectiveness of different storage facilities (jute sack, PICS bag, fertilizer bag, AgroZ® bag, and polypropylene bag) over varying durations (0, 2, 4, 6, and 8 months) in three replications. In the outdoor experiment, traditional and modified gombisa constructed in an open field at the Jimma University Research Site (Eladale), along with different storage duration (initial loading, 2, 4, 6, and 8 months after storage), were evaluated in three replications. The data collected included grain damage percentage, weight loss, seed germination, and proximate analysis. Statistical analysis revealed significant differences in grain damage, weight loss, and seed germination of grains stored in different storage types. Jute sacks showed the most severe damage to grains and weight loss, while PICS and AgroZ® bags had the lowest values. The PICS and AgroZ® bags exhibited the highest seed germination, while the Jute bags had the lowest. In particular, traditional gombisa storage resulted in more significant grain damage, weight loss, and reduced germination than modified gombisa. As storage duration increased, grain damage and weight loss increased significantly in Jute sacks, Polyethylene bags, and traditional gombisa. Furthermore, the proximate analysis showed that storage periods and facilities significantly affected the characteristics of the quality of the maize grain. The moisture content, the crude protein, and the crude fat decreased with longer storage durations in all storage types, while the crude fiber and the ash content increased. The results confirmed the effectiveness of PICS, AgroZ® bags, and modified gombisa in reducing the qualitative and quantitative losses caused by the infestation of storage insect pests. These storage methods can be recommended to protect maize grain for eight months.

The potential neuroprotective of luteolin against acetamiprid-induced neurotoxicity in the rat cerebral cortex.

Acetamiprid is a class of neuroactive insecticides widely used to control insect pests. The current study aimed to investigate the potential neuroprotective effects of luteolin against acetamiprid-induced neurotoxicity in the rat cerebral cortex. Four equal groups of adult male rats (10 in each): control, acetamiprid (40 mg/kg for 28 days), luteolin (50 mg/kg for 28 days), and acetamiprid+luteolin cotreatment were used. Acetamiprid was shown to alter the oxidative state by increasing oxidant levels [nitric oxide (NO) and malondialdehyde (MDA)] and decreasing antioxidants [glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), and catalase-(CAT)], with increased activity of nuclear factor erythroid 2-related factor 2-(Nrf2). Likewise, acetamiprid increases the inflammatory response, as evidenced by increased interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and nuclear factor kappa B-(NF-κB). In contrast, the treatment with luteolin brought these markers back to levels close to normal, showing that it protects neurocytes from oxidative damage and the neuroinflammation effects of acetamiprid-induced inflammation. Luteolin also demonstrated a neuroprotective role via the modulation of acetylcholinesterase (AChE) activity in the cerebral cortex tissue. Histopathology showed severe neurodegenerative changes, and apoptotic cells were seen in the acetamiprid-induced cerebral cortex layer, which was evident by increased protein expression levels of Bax and caspase-3 and decreased Bcl-2 levels. Histochemistry confirmed the neuronal degeneration, as proven by the change in neurocyte colour from brown to black when stained with a silver stain. Luteolin may have a neuroprotective effect against biochemical and histopathological changes induced by acetamiprid in the rat cerebral cortex.

Chromosome-level genome assembly of the bethylid ectoparasitoid wasp Sclerodermus sp. ‘alternatusi’

The Bethylidae are the most diverse of Hymenoptera chrysidoid families. As external parasitoids, the bethylids have been widely adopted as biocontrol agents to control insect pests worldwide. Thus far, the genomic information of the family Bethylidae has not been reported yet. In this study, we crystallized into a high-quality chromosome-level genome of ant-like bethylid wasps Sclerodermus sp. ‘alternatusi’ (Hymenoptera: Bethylidae) using PacBio sequencing as well as Hi-C technology. The assembled S. alternatusi genome was 162.30 Mb in size with a contig N50 size of 3.83 Mb and scaffold N50 size of 11.10 Mb. Totally, 92.85% assembled sequences anchored to 15 pseudo-chromosomes. A total of 10,204 protein-coding genes were annotated, and 23.01 Mb repetitive sequences occupying 14.17% of genome were pinpointed. The BUSCO results showed that 97.9% of the complete core Insecta genes were identified in the genome, while 97.1% in the gene sets. The high-quality genome of S. alternatusi will not only provide valuable genomic information, but also show insights into parasitoid wasp evolution and bio-control application in future studies.

Establishment of RNAi-Mediated Pest Control Method for Red Imported Fire Ant, Solenopsis invicta.

RNAi plays a crucial role in insect gene function research and pest control field. Nonetheless, the variable efficiency of RNAi across diverse insects and off-target effects also limited its further application. In this study, we cloned six essential housekeeping genes from Solenopsis invicta and conducted RNAi experiments by orally administering dsRNA. Then, we found that mixing with liposomes significantly enhanced the RNAi efficiency by targeting for SiV-ATPaseE. Additionally, we observed a certain lethal effect of this dsRNA on queens by our established RNAi system. Furthermore, no strict sequence-related off-target effects were detected. Finally, the RNAi effect of large-scale bacteria expressing dsRNA was successfully confirmed for controlling S. invicta. In summary, this study established an RNAi system for S. invicta and provided a research template for the future development of nucleic acid drugs based on RNAi.

Insect pests incidence of peanut (Arachis hypogaea L.) in the dryland of Kupang District, East Nusa Tenggara, Indonesia

The presence of insect pests is one of the obstacles in efforts to increase peanut production in Kupang District. This study aimed to evaluate farmers’ knowledge of peanut insect pests and assess their adopted control measures and to identify the types of insect pests and their respective incidence rates in peanut crops. Within each sub-district, two villages were selected on the advice of the local extension agents; five farmers were interviewed using predefined checklists. The checklists were designed to gather information about the farmers’ awareness of various pests affecting their peanut crops and the measures they employed to safeguard their crops. The second part of the study involved examining peanut fields in the chosen locations to assess pest infestation. The results revealed that farmers demonstrated a comprehensive understanding of the insect pests frequently linked to peanut cultivation, but the majority of farmers (64.3%) did not try to control insect pests on their peanut plants. Five insect pests were identified on peanut plants: Aphis craccivora, Anoplocnemis phasiana, Aulacophora indica, Chrysodeixis chalcites, and Lamprosema indicata. The incidences of the identified pests varied between 14.1% to 26.8%. Lamprosema indicata exhibited the lowest incidence, while Aphis craccivora had the highest.

ACCOMPLISHMENTS AND FUTURE OF BIOLOGICAL CONTROL AND INTEGRATED CONTROL IN BRAZIL – PART 1

Efforts to biologically control insect pests in Brazil though modest in the past have in recent years been increasing, and the future possibilities of biological control are most promising if certain facilities and conditions are provided. We shall deal here mainly with biological control. Biological control is a natural ecological phenomenon. It is the regulation of plant and animal numbers by natural enemies. Natural enemies are parasites, predators and pathogens.

Genetic Diversity Analysis of Rhynocoris marginatus Fabricius Based on 18S Ribosomal RNA Gene (Heteroptera: Reduviidae)

The R. marginatus are essential components of ecosystem, but also important in the biological control of insect pest, infesting a varity of agro ecosystem and medicine. The present investigation was carried out in the insect molecular genetic variation of 18S Ribosomal RNA gene from R. marginatus. The study was represent by the reduviid insect R. marginatus nucleotide gene sequences were translate amino acid sequence and obtained hydropathy, Domain, Transmembranes of proteins were calculated. The multiple gene sequence alignment of in-silico translated amino acid sequence of the partial ribosomal genes protein of R. marginatus were generated and the phylogenetic relationships were observed.

Viral diversity in the European spruce bark beetle Ips typographus as revealed through high-throughput sequencing

The European spruce bark beetle, Ips typographus is the economically most important biotic damaging agent of Norway spruce. Efforts to delimit beetle populations by trapping, application of chemical insecticides, or mechanically excluding the beetles from their breeding substrates are often expensive and mostly inadequate. The use of natural enemies and viruses is receiving increased research interest as a potential environmentally healthy approach to control pest insect populations, but practical biocontrol methods against I. typographus are still lacking. To learn more about putative enemies of this pest species, we used high-throughput sequencing to determine its viral community using beetles collected at a Finnish forest site. The analysis revealed a diverse community of RNA viruses associated with I. typographus, including novel viruses that could be affiliated with the classified families Benyviridae, Metaviridae, Narnaviridae, Partitiviridae, Phenuiviridae, Solemoviridae, Virgaviridae, Tombusviridae, and proposed family Spiciviridae, as well as unclassified “quenyaviruses”. Based on phylogenetic analysis, the viruses were distinct from, but resembled, unclassified viruses originating from other arthropods, and many of them were distantly related to previously described viruses. The possibility that the viruses could be hosted by other organisms than the beetle itself (associated fungi, nematodes and protozoa) was addressed by bioinformatic and phylogenetic analyses and is discussed.

The effect of chitin on the effectiveness of Beauveria bassiana formulation product to control cocoa pod borer in vitro

Fungal entomopathogens are suggested to be used as a bioinsecticide due to their biological persistence and ecological friendliness. Beauveria bassiana is an entomopathogenic fungus that can effectively control insect pests, including cocoa pod borer. This study aims to determine the level of effectivity of the B. bassiana (Bb) formulation product from Palu against cocoa pod borer pupae in vitro . This research used a completely randomized design (CRD) consisting of two factors: conidia concentrations and chitin treatments, which were repeated thrice. The conidia concentrations consisted of two levels, that were 106 and 107 conidia/mL. The chitin treatment included seven treatments: isolate from Kediri without formulation with chitin (Bb-K), isolate from Palu without formulation with chitin (Bb-P0), four formulations of isolates from Palu with the addition of chitin to various growth media (Bb-P1, Bb-P2, Bb-P3, and Bb-P4), and control (without Bb suspension). Bb-P0 and Bb-P2 treatments at a concentration of 107conidia/mL began to colonize CPB on the third day after the treatment application, while the other formulations started on the fifth day. However, Bb-P0 showed the lowest infection rate at the end of the observation. Contrarily, the data on the pupa-infected ratio showed that the Bb-P2 treatment was the highest compared to other treatments. It conformed to the adult emergence ratio that Bb-P2 exhibited the lowest, which means Bb-P2 has the most virulence of other formula. The result showed that PDA and PDB media-supplemented chitin was the most effective for culturing B. bassiana origin Palu before mass production.

Key residues involved in the interaction between chlorpyrifos and a chemosensory protein in Rhopalosiphum padi: Implication for tracking chemical residues via insect olfactory proteins

The development of advanced biosensors for tracking chemical residues and detecting environmental pollution is of great significance. Insect chemical sensory proteins, including chemosensory proteins (CSPs), are easy to synthesize and purify and have been used to design proteins for specific biosensor applications. Chlorpyrifos is one of the most commonly used chemicals for controlling insect pests in agriculture. This organophosphate is harmful to aquatic species and has long-term negative consequences for the ecosystem. CSPs can bind and carry a variety of environmental chemicals, including insecticides. However, the mechanism by which CSPs bind to insecticides in aphids has not been clarified. In this study, we discovered that RpCSP1 from Rhopalosiphum padi has a higher affinity for chlorpyrifos, with a Ki value of 4.763 ± 0.491 μM. Multispectral analysis revealed the physicochemical binding mechanism between RpCSP1 and chlorpyrifos. Computational simulation analysis demonstrated that the main factor promoting the development of the RpCSP1-chlorpyrifos complex is polar solvation energy. Four residues (Arg33, Glu94, Gln145, Lys153) were essential in facilitating the interaction between RpCSP1 and chlorpyrifos. Our research has improved knowledge of the relationship between CSPs and organophosphorus pesticides. This knowledge contributes to the advancement of biosensor chips for tracking chemical residues and detecting environmental pollution through the use of CSPs.

The Bombyx mori singed Gene Is Involved in the High-Temperature Resistance of Silkworms.

Temperature is an important factor in the growth, development, survival, and reproduction of organisms. The high-temperature resistance mechanism of insects may be significant for use in the prevention and control of insect pests. The silkworm, Bombyx mori, is an important Lepidoptera model species for studies on pest control in agriculture and forestry. We identified a gene in B. mori, the B. mori singed (Bmsn) gene, which is involved in the high-temperature resistance of silkworms. Sn proteins are highly conserved among species in many taxonomic groups. The overexpression of the Bmsn gene promoted the proliferation of silkworm cells, reduced oxidation, and reduced the accumulation of reactive oxygen species under stress. Interfering with the Bmsn gene had the opposite result. We constructed a transgenic B. mori strain that overexpressed the Bmsn gene. The physiological traits of the transgenic strain were significantly improved, and it had stronger high-temperature resistance. The Bmsn gene is involved in the process by which fat bodies respond to high-temperature stress. These findings provide insights into the mechanism of high-temperature resistance of insects and offer a new perspective on agricultural and forestry pest control.

Botanical extracts control the fungal pathogen Colletotrichum boninense in smallholder production of common bean

Anthracnose caused by Colletotrichum spp. remains an intractable problem in the most common bean (Phaseolus vulgaris) production areas worldwide and can cause total yield loss. Many smallholder farmers are familiar with using botanical extracts to control insect pests; however, there is less familiarity with their use to control fungal diseases due to a lack of evidence. Here, we demonstrate that anthracnose could be controlled effectively by pesticidal plant species that are used for insect control. In laboratory trials, water extracts from 11 plant species could inhibit fungal growth (100%) and spore germination (75–100%) equally well to two commercially available fungicides, the synthetic Mancolaxyl and biofungicide Bioderma. In screenhouse trials, anthracnose disease was reduced by the extracts of three plant species. Moreover, bean crop growth in these botanical treatments did not differ significantly from that observed in the commercial fungicide treated plants. Field trials in a smallholder community reporting severe problems with anthracnose showed an effect similar to the screenhouse results. Field trials resulted in bean seed yields approximately 350 kg/ha higher in bean plants treated with Azadirachta indica and Lippia javanica at 10% w/v compared to the negative control untreated plants. In all trials, botanical extracts were as effective as commercially available fungicides, suggesting that these botanical extracts could provide dual-purpose pest and disease management for anthracnose and crop pest insects. The outcomes of this research show that prospects for using locally available resources to control anthracnose on common bean are credible and can be combined with controlling insect pests.

Entomopathogens and their role in insect pest management

Agricultural production faces significant challenges due to the loss of crop yields, highlighting the need for improvements in pest management methods to enhance productivity. Crop growers are increasingly pressured to minimize the use of chemical pesticides without compromising yields. However, managing pests has become more challenging due to pesticide resistance and limited product availability. Consequently, there is an urgent requirement for alternative approaches. Entomopathogens such as fungi, bacteria, viruses, and nematodes emerge as promising alternatives to broad-spectrum chemical insecticides. They have been widely employed to control insect pests in cultivated crops, employing successful strategies such as augmentation and classical biological control. These methods involve applying or introducing bacteria, baculoviruses, fungi, and nematodes. Utilizing entomopathogens offers numerous benefits beyond their effectiveness. These advantages encompass the capacity to treat expansive areas with a sole application, ensuring safety for both humans and non-target organisms. Additionally, their use leads to decreased pesticide residues in food, the conservation of natural enemies, and a boost in biodiversity within managed ecosystems. Entomopathogens present a viable solution by offering effective pest control while addressing environmental, human health, and ecosystem sustainability concerns. The primary emphasis of this review is on the present condition of bio-formulations, the pathogenicity associated with entomopathogens, their mode of action, and the possible implementation of diverse microbial formulations aimed at achieving sustainable pest management.

Negative association between host plant suitability and the fitness cost of resistance to Bacillus thuringiensis (Bacillales:Bacillaceae).

Transgenic crops producing Bacillus thuringiensis (Bt) toxins are commonly used for controlling insect pests. Nearby refuges of non-Bt host plants play a central role in delaying the evolution of resistance to Bt toxins by pests. Pervasive fitness costs associated with resistance, which entail lower fitness of resistant than susceptible individuals in refuges, can increase the ability of refuges to delay resistance. Moreover, these costs are affected by environmental factors such as host plant suitability, implying that manipulating refuge plant suitability could improve the success of the refuge strategy. Based on results from a previous study of Trichoplusia ni resistant to Bt sprays, it was proposed that low-suitability host plants could magnify costs. To test this hypothesis, we investigated the association between host plant suitability and fitness costs for 80 observations from 30 cases reported in 18 studies of 8 pest species from 5 countries. Consistent with the hypothesis, the association between plant suitability and fitness cost was negative. With plant suitability scaled to range from 0 (low) to 1 (high), the expected cost was 20.7% with a suitability of 1 and the fitness cost increased 2.5% for each 0.1 decrease in suitability. The most common type of resistance to Bt toxins involves mutations affecting a few types of midgut proteins to which Bt toxins bind to kill insects. A better understanding of how such mutations interact with host plant suitability to generate fitness costs could be useful for enhancing the refuge strategy and sustaining the efficacy of Bt crops.

Biopesticides: Uses and importance in insect pest control: A review

Biopesticides: Uses and importance in insect pest control: A review