Control Of Insect Pests Research Articles

Impact of diet composition of <I>Corcyra cephalonica</I> (Lepidoptera: Pyralidae) on the development and reproduction of <I>Trichogramma chilonis</I> (Hymenoptera: Trichogrammatidae)

Utilizing parasitoids for augmentative biological control frequently depends on the physiological state of the parasitoids and the pest population density at the time of release. Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) is commonly used as an egg parasitoid for biological insect pest control via augmentation and field release. A crucial component of mass production programmes is the host’s nutritional compatibility. So, the investigations were carried out to study the effect of diet composition of Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) on developmental and reproductive parameters of Trichogramma chilonis Ishii. The T. chilonis was reared on Corcyra cephalonica fed on different diets (D1-D7) in the laboratory at 25℃±1℃ with 75±5% RH. Based on pooled data of two generations T. chilonis had shown significantly highest parasitization of 85.80%, adult emergence percentage 75.00% and sex-ratio 1.62:1 on rice moth eggs obtained from Maize (48.5%) + Sorghum (48.5%) + Groundnut (3%) diet (D5). Trichogramma adult’s emergence was observed earlier (3.10 days) on the host’s eggs reared on the Bajra (100%) diet (D1). In case of adult longevity, the maximum longevity of 7.70 days was recorded on the host’s egg obtained from the D5 diet over the others. These findings may help to improve the developmental and reproductive performance of T. chilonis and an optimized D5 diet may be useful for mass rearing of this egg parasitoid.

Interactive effects of Rhizobacteria for Managing Spodoptera exigua on Shallot Plants (Allium cepa Linnaeus) under Field Conditions

Spodoptera exigua is the primary pest attacking shallot plants from the vegetative to the generative phase. Yield loss caused by S. exigua attack can reach 57%. Rhizobacteria have been known to be used as biocontrol agents for controlling insect pests. The research objectives were to determine and compare the effectiveness of Yuyaos and BPTPH rhizobacteria formula (Bacillus sp.) in suppressing the attack of S. exigua on shallot-growing areas. The study used a completely randomized design (CRD) of 3 treatments and five replications. The treatment consisted of shallot seedlings treated with two types of rhizobacteria (Yuyaos and BPTPH) and water (without rhizobacteria) as control before planting. Beneficial effects of the rhizobacteria on shallot plants were observed in the following variables, including the development of the S. exigua population, damage level of S. exigua, and shallot growth. The results showed that introducing Yuyaos rhizobacteria (RZ2.1AG1, Bacillus thuringiensis), which originated from the rhizosphere of the chili plant, was the best way to protect shallot plants from S.exigua. Effectively reduced the population of S.exigua (78.90%), leaf damage (62.12%), and damage intensity (38.88%). On the other hand, Yuyaos was also influential in increasing tuber growth (11.11%), plant height (43.29%), number of leaves (58.33%), and number of tillers (22.22%).

Effects of Two Prey Species Combinations on Larval Development of the Predatory Ladybird Cheilomenes propinqua.

Feeding on mixed, alternating, or changing diets often favor insect development. With the aim to optimize mass rearing and use for the biological control of insect pests, we investigated the effects of various combinations of high-quality (the green peach aphid Myzus persicae) and low-quality (eggs of the grain moth Sitotroga cerealella) foods on the larval development of a predatory ladybird Cheilomenes propinqua. In the first experiment, eggs and aphids were mixed in different proportions; in the second experiment, larvae switched from feeding on aphids to feeding on eggs. Although the beneficial additive effect of mixed foods was detected in some treatments with limited diets, feeding on various combinations of eggs with aphids never resulted in higher survival, faster development, or a larger size of emerging adults than those observed for feeding on unlimited amounts of aphids. For the practice of biological control, we conclude that, if necessary (for example, in the case of temporary shortage or a lack of aphids in mass rearing facilities or in the case of preventing release of C. propinqua adults in greenhouses), C. propinqua larvae can be fed with grain moth eggs by replacing, mixing, or alternating with aphids, although this will inevitably result in a proportional decrease in pre-adult survival, rate of development, weight, and size of the emerging adults. On the other hand, even a minimal addition of aphids can have a substantial positive effect on larvae fed with grain moth eggs.

Identification of a biomarker for Bacillus thuringiensis strains with high toxicity against Spodoptera frugiperda based on insecticidal gene linkage analysis.

Bacillus thuringiensis (Bt) is a Gram-positive bacterium that produces various insecticidal proteins used to control insect pests. Spodoptera frugiperda is a global insect pest which causes serious damage to crops, but bio-insecticides currently available to control this pest have limited activity and so new ones are always being sought. In this study we have tested the hypothesis that a biomarker for strain toxicity could be found that would greatly facilitate the identification of new potential products. Using genomic sequencing data we constructed a linkage network of insecticidal genes from 1957 Bt genomes and found that four gene families, namely cry1A, cry1I, cry2A and vip3A, showed strong linkage. For 95 strains isolated from soil samples we assayed them for toxicity towards S. frugiperda and for the presence of the above gene families. All of the strains that showed high toxicity also contained a member of the vip3A gene family. Two of them were more toxic than a commercially available strain and genomic sequencing identified a number of potentially novel toxin-encoding genes. The presence of a vip3A gene in the genome of a Bt strain proved to be a strong indicator of toxicity towards S. frugiperda validating this biomarker approach as a strategy for future discovery programs. © 2024 Society of Chemical Industry.

<span><strong>Enhanced thiamethoxam degradation in water  and soil by </strong><em>Phanerochaete </em><strong>sp. Th1 and </strong><em>Ensifer </em><strong>sp. Th2</strong></span>

Thiamethoxam is widely applied to control pest insects, but it causes serious environmental contamination. In this study, the degradation processes of the compound in soil and water collected from a rice field by native microorganisms, by mixed culture of Phanerochaete sp. Th1 and Ensifer sp. Th2, and by both the mixed pure culture and native microorganisms were conducted. The result showed that the mixed culture inoculation increased thiamethoxam in all media. In liquid media, the degradation percentage of the substrate in collected water was 21.8±4.4%, collected water + inoculation was 44.2±5.0%, and mineral medium + inoculation was 98.0±0.4%. Degradation determination in media with 70% collected water and 30% dry soil showed that the main degradation occurred in the liquid phase. The degradation rates in the media with 50% collected water and 50% dry soil were higher in the surface layer, and lower in the bottom. Indigenous microorganisms also played an important role in the degradation process. This study provided valuable information on the thiamethoxam degradation in simulated media of a rice field and the role of Phanerochaete sp. Th1 and Ensifer sp. Th2 to enhance the degradation.

Abamectin exposure causes chronic toxicity and trypsin/chymotrypsin damages in Chironomus kiiensis Tokunaga (Diptera: Chironomidae)

Abamectin has been extensively used in paddy fields to control insect pests. However, little information is available regarding its effects on non-target insects. In this study, we performed acute (3rd instar larvae) and chronic toxicity (newly hatched larvae <24 h) to determine the toxicity effects of abamectin on Chironomus kiiensis. The median lethal concentration (LC50) values of 24 h and 10 d were 0.57 mg/L and 68.12 μg/L, respectively. The chronic exposure significantly prolonged the larvae growth duration and inhibited pupation and emergence. The transcriptome and biochemical parameters were measured using 3rd instar larvae exposed to acute LC10 and LC25 for 24 h. Transcriptome data indicated that five trypsin and four chymotrypsin genes were downregulated, and RT-qPCR verified a significant expression decrease in trypsin3 and chymotrypsin1 genes. Meanwhile, abamectin could significantly inhibit the activities of the serine proteases trypsin and chymotrypsin. RNA interference showed that silencing trypsin3 and chymotrypsin1 genes led to higher mortality of C. kiiensis to abamectin. In conclusion, these findings indicated that trypsin and chymotrypsin are involved in the abamectin toxicity against C. kiiensis, which provides new insights into the mechanism of abamectin-induced ecotoxicity to chironomids.

SiRNA Treatments for Diabetic Neuropathy: Obstacles and Delivery Techniques.

Targeting genes using siRNA shows promise as an approach to alleviate symptoms of diabetic neuropathy. It focuses on neuropathies and distal symmetric polyneuropathy (DSPN) to explore the potential use of small interfering RNA (siRNA) as a treatment for diabetic neuropathy. Timely identification and management of neuropathy play a critical role in mitigating potential complications. RNAi success depends on understanding factors affecting small interfering RNA (siRNA) functionality and specificity. These include sequence space restrictions, structural and sequence features, mechanisms for nonspecific gene modulation, and chemical modifications. Addressing these factors enhances siRNA performance for efficient gene silencing and confidence in RNAi-mediated genomic studies. Diabetic retinopathy, particularly in South Asian, African, Latin American, and indigenous populations, is a significant concern due to its association with diabetes. Ethnicity plays a crucial role in its development and progression. Despite declining rates in the US, global trends remain concerning, and further research is needed to understand regional differences and reinforce ethnicity-based screening and treatment protocols. In this regard, siRNA emerges as a valuable instrument for early intervention strategies. While presenting promising therapeutic applications, siRNA utilization encounters challenges within insect pest control contexts, thereby providing insights into enhancing its delivery mechanisms for neuropathy treatment purposes. Recent advancements in delivery modalities, such as nanoparticles, allow for the controlled release of siRNA. More investigation is necessary to grasp the safety and efficacy of siRNA technology fully. It holds promise in transforming the treatment of diabetic neuropathy by honing in on particular genes and tackling issues such as inflammation and oxidative stress. Continuous advancements in delivery techniques have the potential to enhance patient results significantly. SiRNA targets genes in diabetic neuropathy, curbing nerve damage and pain and potentially preventing or delaying the condition. Customized treatments based on genetic variations hold promise for symptom management and enhancing quality of life.

Insecticide Efficacy of Green Synthesis Silver Nanoparticles on Diaphorina citri Kuwayama (Hemiptera: Liviidae).

Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of Liberibacter asiaticus Jagoueix et al. and Liberibacter americanus Teixeira et al., causal agents of the critical yellow dragon disease or Huanglongbing (HLB), which affects citrus production worldwide. Recently, green synthetic nanoparticles have emerged as a potential alternative to control of agricultural insect pests. The insecticide effect of silver nanoparticles (AgNPs) on 2nd instar nymphs of D. citri under laboratory and greenhouse conditions was evaluated. Mortality was recorded 24, 48, and 72 h after application on D. citri nymphs under both laboratory and greenhouse conditions. The laboratory results showed that AgNPs caused 97.84 and 100% mortality at 32 and 64 ppm, respectively, 72 h after treatment. In the greenhouse, AgNPs caused 78.69 and 80.14% mortality using 64 and 128 ppm 72 h after application. This research is the first to evaluate the green synthesis AgNPs on D. citri and are a promising strategy to control the pest.

Socioeconomic Determinants of Insect Pest Control Methods’ Utilization for Storage in North Central Nigeria

The impetus for this study is the need to understand factors influencing the use of insect pest control methods in North Central Nigeria. Specifically, the study described the socioeconomic characteristics of respondents, assessed awareness and use of insect pest control methods, examined farmers’ considerations and investigated factors influencing insect pest control decisions. Using a structured interview schedule to elicit information, data was collected by means of multi-stage sampling technique to select a total of 384 cowpea farmers for this study. A purposive selection of Kwara and Niger States paved way for the purposive choice of two agricultural zones in Kwara state and one agricultural zone in Niger state. Percentages, frequency counts, ranks, mean, and ordinary least square regression was used to analyze the data. The study revealed that the intended time of sale, time required to apply method, and time of application were the factors most considered for store insect pest control. Ordinary Least Square regression estimates demonstrate positive significant relationship between farm size (t=4.681), group membership (t=4.688), and quantity stored in tons (t=2.312) and intensity of use. Conversely, years of education (t=-2.196), years of cowpea farming experience (t=-3.419), and frequency of extension contact (t=-.534) had significant negative relationship with intensity of use. In conclusion, it is recommended that policy makers and extension staff put into consideration farm size, group membership, quantity stored, years of education, years of cowpea farming experience and frequency of extension contact in optimizing extension strategy for promotion of indigenous and alternative insect pest control methods.

Entomopathogenic fungi against the dengue vector Aedes aegypti: laboratory and semifield assessment

Aedes aegypti, in addition to its association with arboviruses of significant public health concern, poses a considerable challenge to the scientific community, which is actively working to devise innovative strategies to address this threat. Entomopathogenic fungi (EPF) are important bioagents for insect pest control. This study aimed to evaluate the virulence of EPF against Ae. aegypti larvae and adults under laboratory and semifield conditions. Conidia powder from M. anisopliae CG 153 or B. bassiana CG 479, at concentrations ranging from 1×105 to 1×108 conidia/mL, was tested against larvae (N=30) under laboratory conditions, while conidia suspension was used against adults (N=30) via the impregnated filter paper method. Survival curves were compared using the Log-rank test. Both isolates exhibited virulence against larvae and adults, with survival rates ranging from 0% to 64% and 20% to 76%, respectively. Subsequently, both fungi, at a concentration of 107 conidia/mL, were tested against larvae (N=60) and adults (N=60) under laboratory and semifield conditions. Under semifield conditions, larvae and adults showed survival rates ranging from 12% to 35% and 5% to 20%, respectively. The semifield tests produced promising results in decreasing mosquito survival rates. Consequently, this study concludes that the isolates M. anisopliae CG153 and B. bassiana CG 479 have the potential to serve as eco-friendly insecticides against mosquitoes, thus warranting further exploration in the bioprospecting of EPF-based products.

Eco-friendly and Targeted through Next-generation Approaches to Insect Pest Management

Insect pests pose significant challenges to agricultural productivity, human health, and ecosystem stability worldwide. Traditional pest management approaches, heavily reliant on broad-spectrum chemical insecticides, have led to the development of insecticide resistance, unintended effects on non-target organisms, and environmental contamination. In response to these challenges, next-generation approaches to insect pest management are emerging, focusing on eco-friendly and targeted strategies. This review article explores the latest advancements in sustainable pest management, including the use of biopesticides, semiochemicals, biotechnology-based approaches, and integrated pest management (IPM) strategies. Biopesticides, derived from natural sources such as plants, microorganisms, and insects, offer effective and environmentally benign alternatives to synthetic insecticides. Semiochemicals, including pheromones and allelochemicals, can be exploited for pest monitoring, mating disruption, and attract-and-kill strategies. Biotechnology-based approaches, such as RNA interference (RNAi), CRISPR/Cas9 gene editing, and transgenic crops, provide novel tools for targeting specific pest species and reducing reliance on chemical insecticides. IPM strategies, which combine multiple pest management tactics based on ecological principles, offer a holistic and sustainable approach to pest control. The adoption of these next-generation approaches faces challenges, including regulatory hurdles, public acceptance, and the need for further research and development. However, by embracing eco-friendly and targeted pest management strategies, we can reduce the environmental impact of insect pest control, promote biodiversity conservation, and ensure sustainable food production for a growing global population. Future research should focus on optimizing and integrating these approaches, understanding their long-term ecological impacts, and developing effective knowledge transfer mechanisms to promote their widespread adoption.

Determination of essential oil components of Ammi L. genus in Türkiye and their effects on some storage pests

Effects of essential oil components obtained by hydrodistillation of Ammi genus members (Ammi majus L., Ammi visnaga L. (Lam.)), which have important chemical and active components were investigated against two important storage pests; fig borer Cadra cautella (Walker) (Lepidoptera: Pyralidae) and flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). A total of 23 and 14 components were detected in A. majus and A. visnaga, respectively, and the product yield was found to be 96.05%, 82.53%. Among them, the major components for A. majus are 2 heptadecanone, benzoic acid, 2 pentadecanone while for A. visnaga they are linalol, nonadecane, carvacrol. Essential oil of A. visnaga extended the adult emergence times in E. kuehniella and C. cautella while the increase in pupation time was found statistically significant only in E. kuehniella. A. visnaga essential oil reduced the adult life span in E. kuehniella at the highest dose while a decrease was detected in both doses applied in C. cautella. Adult weight and number of eggs decreased due to the application of A. visnaga in both insects. Also, alterations were observed in the adult emergence, pupation time, and pupal period. In E. kuehniella and C. cautella, adult life spans, weights and egg production of females showed statistically significant decreases depending on the application of A. majus essential oil. The findings obtained within the scope of the current study reveal that the essential oils of A. majus and A. visnaga species have the potential to be used in the control of storage pest insects.

Investigating the Potency of Camphor Combined With Kerosene on the Emergence of Anopheles Gambiae

Background Camphor has a long-term application history in the control of insect pests and their mixture with kerosene is not an exception in the control of mosquitoes. Objectives Due to differences in larval biology and positioning in breeding sites, this study was designed to reassess the potency of camphor mixed with kerosene against the emergence of Anopheles mosquitoes in order to ascertain that efficacy of a treatment may not differ greatly with different mosquito species. Methodology Larvae and pupae of Anopheles mosquitoes were collected from Ndokwa West Area of Delta State, Nigeria using standard World Health Organization method and left to acclimatize for 6 h in the Insectary before exposure. Mosquitoes were confirmed as Anopheles gambiae. Camphor (2 g) and its mixture with kerosene in equal ratio were introduced into 100, 200, and 400 mL of water which equated 0.02%, 0.01%, and 0.005%, respectively. Anopheles mosquitoes exposed to only water served as control for the experiment. Twenty larvae and pupae in their third stage of larval development was first sorted into 1000 mL glass beaker and then introduced into various treatment concentrations in 3 replicates. Results Highest mortality was recorded in larvae exposed to 0.02% of camphor mixed with kerosene. Pupae exposed to same concentration compared favorably. Lethal dosage (LD50 and LD95) of camphor exposed to Anopheles larvae and pupae ranged from 0.002% to 0.004% and 0.021% to 0.491%, respectively. More so, values were 0.002% and range from 0.010% to 0.021% in camphor mixed with kerosene, respectively. Conclusion Therefore, the intensification in the use of camphor mixed with kerosene among the population in mosquito breeding sites would reduce the mosquito biting activities and diseases in the locality.

Advancing RNAi-based Strategies for Eco-friendly and Targeted Insect Pest Management in Sustainable Agriculture

The RNA interference (RNAi) has emerged as a promising approach for targeted and eco-friendly insect pest management in sustainable agriculture. The RNAi involves the silencing of specific genes through the introduction of double-stranded RNA (dsRNA), leading to the degradation of complementary mRNA and subsequent reduction in the expression of targeted proteins. This chapter provides a comprehensive overview of the current state and future prospects of RNAi-based strategies for insect pest control. We discuss the molecular mechanisms underlying RNAi, delivery methods for dsRNA, and the design and selection of effective target genes. The application of RNAi in controlling various insect pests, including lepidopterans, coleopterans, and hemipterans is extensively reviewed. also highlight the potential challenges and limitations associated with RNAi-based pest management, such as off-target effects, variable efficacy across insect species, and the development of resistance. Strategies to overcome these challenges, including the use of nanoparticle-based delivery systems and the combination of RNAi with other pest control methods, are explored. Furthermore, discuss the environmental and ecological considerations surrounding the use of RNAi in agriculture, emphasizing the importance of assessing non-target effects and the need for appropriate risk assessment frameworks. The chapter concludes by outlining future research directions and the potential for RNAi to revolutionize insect pest management, contributing to the development of sustainable and resilient agricultural systems.

Role of CYP9E2 and a long non-coding RNA gene in resistance to a spinosad insecticide in the Colorado potato beetle, Leptinotarsa decemlineata.

Spinosads are insecticides used to control insect pests, especially in organic farming where limited tools for pest management exist. However, resistance has developed to spinosads in economically important pests, including Colorado potato beetle (CPB), Leptinotarsa decemlineata. In this study, we used bioassays to determine spinosad sensitivity of two field populations of CPB, one from an organic farm exposed exclusively to spinosad and one from a conventional farm exposed to a variety of insecticides, and a reference insecticide naïve population. We found the field populations exhibited significant levels of resistance compared with the sensitive population. Then, we compared transcriptome profiles between the two field populations to identify genes associated primarily with spinosad resistance and found a cytochrome P450, CYP9E2, and a long non-coding RNA gene, lncRNA-2, were upregulated in the exclusively spinosad-exposed population. Knock-down of these two genes simultaneously in beetles of the spinosad-exposed population using RNA interference (RNAi) resulted in a significant increase in mortality when gene knock-down was followed by spinosad exposure, whereas single knock-downs of each gene produced smaller effects. In addition, knock-down of the lncRNA-2 gene individually resulted in significant reduction in CYP9E2 transcripts. Finally, in silico analysis using an RNA-RNA interaction tool revealed that CYP9E2 mRNA contains multiple binding sites for the lncRNA-2 transcript. Our results imply that CYP9E2 and lncRNA-2 jointly contribute to spinosad resistance in CPB, and lncRNA-2 is involved in regulation of CYP9E2 expression. These results provide evidence that metabolic resistance, driven by overexpression of CYP and lncRNA genes, contributes to spinosad resistance in CPB.

Chemical Composition and Mosquitocidal activity of the methanolic leaf extracts from Ziziphus mauritiana L. against Aedes aegypti L. and Culex quinquefasciatus Say.

Mosquito vectors are a significant cause of pathogen transmission to both animals and humans. Mosquitoes are responsible for transmitting various diseases, including chikungunya, filariasis, West Nile fever, dengue, malaria, and Zika fever, placing approximately 80% of the world's population at risk of infection at any given time. Controlling mosquitoes has become a multifaceted challenge, influenced by diverse environmental factors such as deforestation, urbanization, and climate change on a global scale. For centuries, medicinal plants have been utilized as bioinsecticides to control insect pests. Ziziphus mauritiana, also known as Chinese apple or Indian jujube is a deciduous thorny tree or shrub. Different parts of the Z. mauritiana plant have been traditionally used to treat various common diseases, a practice still prevalent in India and China. In the current investigation, the chemical properties of the Z. mauritiana leaf extract were examined through UV-Vis Spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR), and GC-MS Analysis. Second and fourth instar larvae, as well as pupae, of Aedes aegypti and Culex quinquefasciatus were subjected to different concentrations of the methanolic extract of Z. mauritiana for 24 h and 48 h to assess larvicidal and pupicidal activity. The FT-IR spectrum analysis revealed the presence of various functional groups in the chemical compounds extracted from Z. mauritiana, including amines, aromatics, alkanes, alkyls, carbonyls, and carboxylic acids. Additionally, GC-MS analysis identified Isoborneol (25.37%), 4-Acetylbutyric Acid (26.82%), and 2-Vinyl-9-[Beta-D-Ribofuranosyl] Hypoxanthine (24.24%) as the three major phytoconstitutents in the methanol extracts of Z. mauritiana. Regarding the larvicidal activity, the methanolic extract of Z. mauritiana exhibited LC50 values of 155.67 mg/L and 208.57 mg/L for second instar larvae, and 177.68 mg/L and 252.13 mg/L for fourth instar larvae of Cx. quinquefasciatus and Ae. aegypti, respectively, after 24 h of exposure. For pupicidal activity, the LC50 values were 502.02 mg/L and 514.99 mg/L on pupae of Cx. quinquefasciatus and Ae. aegypti, respectively, within 24 h. Overall, the GC-MS analysis provides valuable insights into the chemical composition of the Z. mauritiana extract, highlighting its potential as a natural and eco-friendly alternative for combating insect vectors and contributing to integrated mosquito management programs.

A faster killing effect of plastid-mediated RNA interference on a leaf beetle through induced dysbiosis of the gut bacteria

The expression of double-stranded RNAs (dsRNAs) from the plastid genome has been proven to be an effective method for controlling herbivorous pests by targeting essential insect genes. However, there are limitations to the efficiency of plastid-mediated RNA interference (PM–RNAi) due to the initial damage caused by the insects and their slow response to RNA interference. In this study, we developed transplastomic poplar plants that express dsRNAs targeting the β-Actin (dsACT) and Srp54k (dsSRP54K) genes of Plagiodera versicolora. Feeding experiments showed that transplastomic poplar plants can cause significantly higher mortality in P. versicolora larvae compared with nuclear transgenic or wild-type poplar plants. The efficient killing effect of PM–RNAi on P. versicolora larvae was found to be dependent on the presence of gut bacteria. Importantly, foliar application of a gut bacterial strain, Pseudomonas putida, will induce dysbiosis in the gut bacteria of P. versicolora larvae, leading to a significant acceleration in the speed of killing by PM–RNAi. Overall, our findings suggest that interfering with gut bacteria could be a promising strategy to enhance the effectiveness of PM–RNAi for insect pest control, offering a novel and effective approach for crop protection based on RNAi technology.

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.