Polyphagous Insect Research Articles

Planting date in South Kivu, eastern DR Congo: A real challenge for the sustainable management of Spodoptera frugiperda (Lepidoptera: Noctuidae) by smallholder farmers.

There is growing research interest in the fall armyworm (FAW) Spodoptera frugiperda, a polyphagous insect that is a major pest of maize crops worldwide. We investigated the relationship between planting date of maize and FAW infestation in South Kivu, eastern Democratic Republic of Congo, in two sampling seasons (September to October 2020 and February to March 2021). Five planting dates were considered for 45 fields in each season. The incidence, severity of attack and larval density of FAW were assessed at the 8-leaf stage (V8) of maize development in monoculture and intercropping systems. Planting period, classified as late or early, had a strong influence on FAW larval density, incidence and severity. The results showed that the late planting period (mainly on 30 October in season-1 and 30 March in season-2) had the highest larval density, incidence and severity of attack compared to the early planting period (15 September in season-1 and 01 Mars in season-2). During the season-1, five larval stages were found in the same field, whereas all larval stages were present in season-2, regardless of planting period. High densities of L4, L5 and L6 larvae were much more associated with late planting and incidence appeared to be highest when these larvae were present. The presence of L2 and L3 larval stages was observed in maize cropping systems intercropped with soybean and peanuts, while maize in monoculture and intercropped with cassava and beans was colonized by L4, L5 and L6 larvae. This study highlights the existence of different maize planting dates in South Kivu and demonstrates that late plantings have significant FAW infestations compared to early plantings. It provides a basis for developing climate-smart integrated pest management.

Ex vivo delivery of dsRNA targeting ryanodine receptors for control of Tuta absoluta.

RNA interference (RNAi) is an endogenous eukaryote viral defence mechanism representing a unique form of post-transcriptional gene silencing. Owing to its high specificity, this technology is being developed for use in dsRNA-based biopesticides for control of pest insects. Whilst many lepidopteran species are recalcitrant to RNAi, Tuta absoluta, a polyphagous insect responsible for extensive crop damage, is sensitive. Ryanodine receptors (RyRs) are intracellular calcium channels regulating calcium ion (Ca2+) release. The chemical pesticide class of diamides functions agonistically against lepidopteran RyR, resulting in uncontrolled Ca2+ release, feeding cessation and death. Resistance to diamides has emerged in T. absoluta, derived from RyR point mutations. RNAi was used to target RyR transcripts of T. absoluta. Data presented here demonstrate the systemic use of exogenous T. absoluta RyR-specific (TaRy) dsRNA in tomato plants (Solanum lycopersicum) to significantly downregulate expression of the target gene, resulting in significant insect mortality and reduced leaf damage. Using a leaflet delivery system, daily dosing of 3 μg TaRy dsRNA for 72 h resulted in 50% downregulation of the target gene and 50% reduction in tomato leaf damage. Corrected larval mortality and adult emergence were reduced by 38% and 33%, respectively. TaRy dsRNA demonstrated stability in tomato leaves ≤72 h after dosing. This work identifies TaRy as a promising target for RNAi control of this widespread crop pest. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluation of the insecticidal activity of Acorus calamus rhizome and Chrysopogon zizanioides roots essential oils against mealybug, Phenacoccus solenopsis

The mealybug, Phenacoccus solenopsis, a polyphagous insect pest, is considered a destructive pathogen and has invaded almost all parts of the world. The main aim of the study is to extract essential oil from Acorus calamus rhizome and Chrysopogon zizanioides roots against P. solenopsis. The essential oils were subjected to an in vitro toxicity analysis on the second and third instar stages of papaya mealybugs. At 10 μL/mL, A. calamus showed 33 ± 1.2% mortality after 24 h, and it was high (61 ± 1.7% mortality) at 50 μL/mL essential oil (p < 0.01). The combination of A. calamus and C. zizanioides essential oils exhibited a lower LC50 value than individual essential oils and revealed a synergistic effect. The essential oils inhibited the expression of acetylcholinesterase and glutathione-S-transferase in mealybugs and were dose-dependent (p < 0.05). The mealybugs were exposed to different concentrations of A. calamus rhizome, roots of C. zizanioides, a mixture of these two essential oils, imidacloprid (the positive control), and water (the negative control). The amount of total protein content was 0.47 ± 0.01 µg/g in the control animals, and it was reduced in the essential oil (A. calamus)-treated mealybug (p < 0.01). Similarly, the essential oil of C. zizanioides treated mealybugs showed reduced carbohydrate (p < 0.01) and lipid content (p < 0.05). The 2nd and 3rd instar stages of mealybugs were used to inoculate papaya trees. The spray treatment was used to analyze the effect of essential oils on the mealybug population. After 24 h treatment, 1.25% A. calamus induced 47 ± 1.2 mortality and was increased to 49.5 ± 0.4% after 72 h. The mortality increased with an increasing concentration of essential oil spray than treatment time (p < 0.01). The combination of these two essential oils improved mortality more than individual essential oils revealed synergy (p < 0.01). The present finding provides for the use of essential oils to control mealybugs in papaya plantations, and the application of eco-friendly pesticides could reduce the usage of synthetic pesticides.

Disentangling the worldwide invasion process of Halyomorpha halys through approximate Bayesian computation.

Halyomorpha halys is a polyphagous insect pest, which was first found outside its native regions in 1996, and since then it has rapidly spread worldwide causing damage to agriculture. Investigating the genetic diversity among H. halys populations is essential to understand the colonization history out of its native areas. Analyses based on mtDNA indicate multiple invasions from Asia to European and American continents, as well as serial invasions within invaded countries, but the colonization dynamics are still debated. Recently, genome-wide data (ddRAD) have been published to investigate the genomic structure of H. halys, proposing China as a putative source of multiple serial invasion events to Europe and the Americas. In this study we re-analyze published ddRAD sequences from worldwide populations of H. halys to better elucidate the colonization process. We assessed the genetic diversity in native populations identifying genetic differentiation between populations in China. Furthermore, we observed a complex pattern of population structure in the invaded countries, that may have originated from the occurrence of multiple independent colonization waves through time, from sub-populations present in the native range to Europe and the Americas. We tested alternative colonization hypotheses through Approximate Bayesian Computation comparison of demographic scenarios. Our results support multiple waves of migration from East China to invaded territories and the occurrence of European and American bridgehead effects. These results underline the importance of demographic inference through genome-wide data to investigate biological invasions, whose knowledge become fundamental to establish new strategies of management and control of invasive species.

Female sex pheromone of Spodoptera frugiperda Vietnam population and a selected lure for adult monitoring in maize fields

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a serious polyphagous insect pest that has a preference for maize and which can cause considerable damage to crops, resulting in significant crop losses. It is now established in many countries worldwide. Female sex pheromones play an important role in monitoring and mass trapping for the management of this insect pest. In this study, the female sex pheromone of FAW in Vietnam was analyzed by gas chromatography-mass spectrometry (GC–MS). The virgin female’s pheromone gland extracts of FAW contained Z9-14:Ac, Z11-16:Ac, Z7-12:Ac, and Z9-12:Ac, with ratios of 87.0:12.0:0.6:0.4 (Hanoi) and 84.0:15.0:0.6:0.4 (Phutho). During the field test, the synthetic pheromone blends of three components (Z9-14:Ac, Z11-16:Ac, and Z7-12:Ac) at natural proportions of the local populations (87.3:12.0:0.7 and 84.0:15.0:1.0) and two components (Z9-14:Ac and Z7-12:Ac) (99:1) were found to be more attractive to FAW male moths. Pheromone traps with these optimal lures can be used to monitoring the population of FAW adults in maize fields. Pheromone lures and traps can be researched and developed as part of an integrated pest management for FAW in Vietnam.

A different approach to identifying thermal parameters for invasive species.

The brown marmorated stinkbug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is a polyphagous invasive insect found in the eastern United States in 1998 but became a major agricultural pest in 2010. Environmental temperatures regulate the location of invasive species establishment in new locations. To determine those areas where an invasive species might establish it is essential to understand the metabolic response of all life stages to temperature. Differential scanning calorimetry is a useful tool to monitor living organisms' metabolism at different temperatures, providing vital information related to the ability of the species to survive in new environments. The information obtained from isothermal and scanning calorimetric experiments on all the life stages of H. halys indicates that the third instar is the most thermoresponsive stage and eggs and fifth instar are the least thermoresponsive, whereas the third instars exhibit a broad range of thermoresponsiveness as compared to all other developmental stages. The recorded values for lower, optimal, and upper developmental temperatures in this study were similar to those reported by other researchers using laboratory and field data to develop degree-day models. This method can help in the rapid development of degree day models to improve and synchronize control efforts for newly invasive species.

The Spotted Lanternfly Contains High Concentrations of Plant Hormones in its Salivary Glands: Implications in Host Plant Interactions.

The spotted lanternfly (SLF), Lycorma delicatula is an invasive species in the United States that has emerged as a significant pest in vineyards. This polyphagous insect causes significant damage to grapevines and tree of heaven (TOH). SLF feeds voraciously on plant tissues using its piercing and sucking mouthparts through which it injects saliva and uptakes plant sap. Despite its impact, research on fundamental mechanisms mediating SLF interactions with their predominant hosts is limited. This study documents the morphology of salivary glands and quantifies plant hormones in salivary glands of SLF adults fed on grapevines and TOH using Liquid Chromatography-Mass Spectrometry (LC/MS). SLF adults have one pair of large salivary glands, ranging from 10 to 15mm in length that extend from the insect's head to the last sections of the abdomen. The salivary glands of SLF contain salicylic acid (89 ng/g), abscisic acid (6.5 ng/g), 12-oxo-phytodienoic acid (5.7 ng/g), indole-3-acetic acid (2 ng/g), jasmonic acid (0.6 ng/g), jasmonic acid isoleucine (0.037 ng/g), and the cytokinin ribosides trans-zeatin (0.6 ng/g) and cis-zeatin (0.1 ng/g). While the concentrations of these hormones were similar in insects fed on grapevines and TOH, abscisic acid was more abundant in insects fed on grapevines, and jasmonic acid isoleucine was only detected in insects fed on grape. These results are discussed in the context of the possible implications that these hormones may have on the regulation of plant defenses. This study contributes to our understanding of the composition of SLF saliva and its potential role in plant immunity.

To be a good killer: Evaluation of morphometry and nematodes-bacteria complex effect on entomopathogenic nematodes virulence against wireworms

Entomopathogenic nematodes (EPNs) have emerged as a promising tool for controlling soil-dwelling crop pests. However, their efficacy varies according to EPN populations and targeted hosts. Wireworms are polyphagous insects causing significant crop losses, especially since the ban on pesticides previously used for their control. They are highly resistant to EPN populations and require high number of infective juveniles (IJs) to achieve optimal mortality rates. In this research, we collected and compared the virulence of 16 EPN populations, of foreign origin, purchased or collected from wireworms infested fields. Then, we have tested two hypotheses: (i) smaller nematodes induce heightened mortality rates against wireworms; (ii) virulence levels can be linked to nematodes-bacteria complex. Mortality rates scaled from three to 43 % after 56 days of continuous exposure across the 16 tested EPN populations (Heterorhabditis spp and Steinernema spp.). Morphometric analysis of IJs revealed both intra- and interspecific variations in length and diameter among populations. Interestingly, while EPN length influence mortality at three days post-inoculation. We found leaner IJs (< 25 µm) to induce higher mortality rates at 56 days post-inoculation. To better determine the structure and dimensions of the primary entry routes utilized by EPNs, we provide optical microscope micrographs of wireworm Agriotes spp. spiracle, anal sclerotized coating anus and anal muscles. Symbiotic bacteria of each EPN population were identified, and a biochemical characterization was performed using Analytical Profile Index tests. The symbiotic bacteria belong to the species Photorhabdus antumapuensis, P. laumondii subsp. laumondii, P. thracensis, Xenorhabdus bovienii and X nematophila. Bacteria biochemical profiles did not reflect the differences in virulence of nematodes-bacteria complex against wireworms. These findings highlight the importance of considering EPN morphometry and intraspecific variability in designing applications to control wireworms.

Toxicity and deterrence of pyroligneous extracts on Liriomyza sativae (Diptera: Agromyzidae)

Liriomyza sativa is a cosmopolitan and polyphagous insect, a key pest of crops such as tomato and melon. The inadequacy of insecticide application techniques has developed resistant populations. The objective of this research was to evaluate the toxicity, insecticidal activity and deterrence of pyroligneous extracts on the leafminer fly. The experiments were carried out under laboratory conditions of 25 ± 2°C and humidity of 60 ± 10%. For the toxicity test, solutions were prepared in different concentrations by diluting them in distilled water. Leaf discs containing L. sativae larvae were immersed in the solutions. For insecticidal activity and deterrence tests, jack bean plants were subjected to application of treatments using an airbrush, spraying 6 mL of the solutions on each plant. All extracts showed significant mortality for the larvae, with emphasis on the pyroligneous extract of coffee straw at 350ºC. The extracts did not interfere with the other developmental stages of the leafminer fly. The pyroligneous extract from the commercial company Agttec and the coffee straw extract at 600ºC were classified as attractive and the coffee straw extract at 350ºC as detergent. It is concluded that pyroligneous extracts can be used in the management of L. sativae.

Feeding and Growth Response of Fall Armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) towards Different Host Plants.

The fall armyworm, Spodoptera frugiperda, is a major migratory polyphagous insect pest of various crops. The essential nutrient and mineral profile of the host plants determines the feeding fitness of herbivorous insects. As a result, the growth and development of insects is affected. To determine the effect of the nutrient and mineral profile of different host plants (maize, castor bean, cotton, cabbage, okra, and sugarcane) on the growth and development of S. frugiperda, biological parameters like larval weight, pupal weight (male/female), and feeding and growth indices were calculated. The proximate compositions such as crude protein, crude fat, crude fibre, and ash and mineral contents of the tested host plants showed significant differences (p < 0.05). The feeding indices on these host plants also differed significantly (p < 0.05). The maximum relative growth rate (RGR), relative consumption rate (RCR), and consumption index (CI) were recorded in S. frugiperda larvae that fed on maize and castor bean leaves. The crude protein, dry matter, and ash contents in maize and castor bean were significantly higher and positively correlated with the RGR and RCR of S. frugiperda larvae. The larval, male and female pupal weights were the maximum in the larvae feeding on the castor bean host plant. These findings provide novel information based on nutritional ecology to develop sustainable integrated pest management strategies using selective crop rotation.

Evaluation of diets from various maize hybrids reveals potential tolerance traits against Spodoptera littoralis (Boisd) as measured by developmental and digestive performance.

Spodoptera littoralis (Boisd) (Lepidoptera: Noctuidae) is a highly polyphagous insect that significantly reduces agricultural production of several food staples. We evaluated performance of S. littoralis on several meridic diets based on various maize hybrids, including Oteel, Simon, Valbum, SC703, and SC704. Growth, feeding behaviours, and activity of digestive enzymes of S. littoralis were examined under laboratory conditions. In addition, selected biochemical characteristics of maize hybrid seeds were evaluated, including starch, protein, anthocyanin, as well as phenolic and flavonoid contents, to examine relationships between plant properties and digestive performance of S. littoralis. Performance of S. littoralis on maize hybrids, as measured by nutritional indices, was related to both proteolytic and amylolytic activities quantified using gut extracts. Larval S. littoralis reared on SC703 exhibited the highest efficiency of conversion of digested food, while the lowest was recorded in those fed on the Oteel hybrid. S. littoralis reared on SC703 and Oteel also exhibited the highest and lowest relative growth rates, respectively. The highest levels of proteolytic activity in S. littoralis were measured from larvae reared on the SC703 hybrid, while the lowest levels occurred on the Oteel and Valbum hybrids. Amylolytic activity was lowest in larvae reared on SC703 and Valbum hybrids and highest in larvae reared on the Oteel hybrid. Our results suggest that the SC703 hybrid was the most suitable host for S. littoralis, while the Oteel hybrid demonstrated the greatest level of tolerance against S. littoralis of those evaluated. We discuss the potential utility of maize hybrids exhibiting tolerance traits against this cosmopolitan pest with reference to cultivation of tolerant varieties and identification of specific tolerance traits.

Age‐stage, two‐sex life table and transcriptome analysis reveal the adaptation of Liriomyza trifolii to different host plants

AbstractLiriomyza trifolii (Burgess) (Diptera: Agromyzidae) is a polyphagous insect that is widely known for its invasiveness. Understanding the adaptation of L. trifolii to different host plants is critical in formulating effective approaches for integrated pest management (IPM). In this study, the effects of various host plants on L. trifolii were investigated by age‐stage, two‐sex life tables and transcriptome analysis. Our results show that the growth rate of immature L. trifolii on sponge gourd increased significantly relative to bean, but mortality was high. Mature L. trifolii adapted to sponge gourd had significantly increased longevity as compared to flies adapted to bean but exhibited reduced fecundity. The net reproductive rate, the intrinsic rate of increase, and the finite rate of increase of L. trifolii adapted to sponge gourd were significantly lower than those of flies adapted to bean. Transcriptome analysis showed the presence of 150 up‐ and 617 downregulated differentially expressed genes in L. trifolii adapted to sponge gourd as compared to flies adapted to bean. Genes encoding glutathione‐S‐transferase, cytochrome P450, and trypsin were significantly downregulated in L. trifolii adapted to sponge gourd as compared to bean. This study provides valuable insight into host plant effects on L. trifolii and provides a basis for the subsequent development of IPM measures such as push and pull, crop rotation, and biopesticide development.

Field efficacy of insecticides for suppressing white mango scale insect (Aulacaspis tubercularis Newstead) (Hemiptera: Diaspididae) in southwest Ethiopia

White mango scale (WMS) Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) is a polyphagous armored scale insect which is considered one of the key pests of mango (Mangifera indica L.) around the world. Mango is widely grown in Ethiopia whereas its production is challenged by WMS in the last decade. Effective formulations that could help manage the scale as part of IPM practice were sought from field experiments at Seka mango farm, Ethiopia in 2019 and 2020 seasons. The study aimed to evaluate the efficacy of some formulations against WMS on mango trees. Randomized complete block designs with three replications were used for the experiments and each tree served as a plot. Allocation of each treatment within each replication was done randomly. The treatments were applied sequentially three times at 14 days interval using motorized Knapsack sprayer coinciding with peak period of natural infestation. Scale numbers before and after each spray were counted using a microscope with LCD. Sum of live crawler, female and male was registered as WMS count data. Results showed that dimethoate, diazinon, imidacloprid & λ-cyhalothrin sprayed alone; dimethoate rotated with imidacloprid & λ-cyhalothrin, chlorpyrifos-ethyl rotated with paraffin, and diazinon rotated with azadirachtin, caused total mortality of the scales. The results also showed that, chlorpyrifos-ethyl, deltamethrin, paraffin oil and λ-cyhalothrin sprayed alone caused percent reduction with range 83–95 % in both seasons. Hence, the study revealed that dimethoate, diazinon, imidacloprid & λ-cyhalothrin applied individually, dimethoate rotated with imidacloprid & λ-cyhalothrin, chlorpyrifos-ethyl rotated with paraffin and diazinon rotated with azadirachtin fully protect mango trees from WMS and significantly superior to other treatments. Therefore, chemical control of A. tubercularis may consider the use of these materials as foliar application and can be used as components for integrated pest management plans for WMS. However, application in the form of rotation is preferred to the alone spray as the former could substantially reduce the likelihood of inducing pesticide resistance. Cost implications and effects of the products on the natural enemy and residual toxicity in fruits need to be studied.

What's on the menu? A novel molecular gut content analysis to investigate the feeding behavior of phytophagous insects.

The relationship between phytophagous insects and plants is a central aspect of food webs and ecosystem functioning. The introduction of new species into an environment can have significant impacts on the food web of a native ecosystem. In many cases, there is a lack of knowledge on the biology and feeding behavior of invasive species prior their introduction and in the invaded regions. Gut content analyses of insects have provided valuable information on the host spectrum of insects. However, current approaches are time-consuming and costly. Here, we describe a new molecular gut content analysis (GCA) approach using the Oxford Nanopore (ONT) Flongle sequencing platform to characterize the plant DNA present in the gut of the highly polyphagous insect species Halyomorpha halys. We demonstrate that this technique efficiently amplifies and correctly identifies plant DNA in a mock community. We performed a feeding experiment to determine the sensitivity of this approach and to assess how long the plant DNA can be detected. All plants used in the feeding experiment were correctly identified and detected after 56 days. Surprisingly, we also detected various plant genera that were not included in the feeding experiment and thus were likely ingested months before the experiment. Our study suggests that the GCA using the ONT Flongle sequencing platform represents a rapid and cost-efficient diagnosis of the dietary preferences, host range, and the diversity of consumed plant species of pest insects with high precision.

Population comparison of innate and plastic host plant preference and performance in a polyphagous insect

Population comparison of innate and plastic host plant preference and performance in a polyphagous insect

Comparative Biology of Guava Fruit Fly &lt;i&gt;Bactrocera correcta&lt;/i&gt; (Bezzi)

Fruit flies are polyphagous insect pests, infesting various fruits and vegetables. The host preference and biology of guava fruit fly Bactrocera correcta (Bezzi) were studied on 17 hosts. Biological parameters such as incubation period, maggot and pupal period, maggot and pupal weight, pupal recovery, adult emergence, total fecundity and adult longevity were studied. All biological parameters were significantly influenced by the host fruits. The results showed that the total developmental period was longer on pomegranate (26.7± 2.1 days), ber (26.1± 2.4 days) and custard apple (25.1± 1.5 days); while shorter period was observed on sweet banana (20.1± 1.6 days). Pupal recovery was maximum on sweet banana (93.33%) and lowest on mango (Totapuri) (42%). The adult emergence was also more on sweet banana (90%) and survived for longer period. Sweet banana was preferred for oviposition followed by guava, papaya, and sapota.

Identification and expression dynamics of CYPome across different developmental stages of Maconellicoccus hirsutus (Green)

Maconellicoccus hirsutus is a highly polyphagous insect pest, posing a substantial threat to various crop sp., especially in the tropical and sub-tropical regions of the world. While extensive physiological and biological studies have been conducted on this pest, the lack of genetic information has hindered our understanding of the molecular mechanisms underlying its growth, development, and xenobiotic metabolism. The Cytochrome P450 gene, a member of the CYP gene superfamily ubiquitous in living organisms is associated with growth, development, and the metabolism of both endogenous and exogenous substances, contributing to the insect's adaptability in diverse environments. To elucidate the specific role of the CYP450 gene family in M. hirsutus which has remained largely unexplored, a de novo transcriptome assembly of the pink mealybug was constructed. A total of 120 proteins were annotated as CYP450 genes through homology search of the predicted protein sequences across different databases. Phylogenetic studies resulted in categorizing 120 CYP450 genes into four CYP clans. A total of 22 CYP450 families and 30 subfamilies were categorized, with CYP6 forming the dominant family. The study also revealed five genes (Halloween genes) associated with the insect hormone biosynthesis pathway. Further, the expression of ten selected CYP450 genes was studied using qRT-PCR across crawler, nymph, and adult stages, and identified genes that were expressed at specific stages of the insects. Thus, the findings of this study reveal the expression dynamics and possible function of the CYP450 gene family in the growth, development, and adaptive strategies of M. hirsutus which can be further functionally validated.

Comparative proteomic analysis of resistant and susceptible cotton genotypes in response to leaf hopper infestation

The cotton leaf hopper is a major pest in cotton, causing a hopper burn in leaves. In this study, a comparative proteomic analysis of NDLH2010 (Resistant) and LRA5166 (Susceptible), infected with leaf hopper, was employed using a nano LC-MS/MS approach. A total of 1402 proteins varied significantly between leaf hopper-infected and control plants. The resistant and susceptible genotypes had differentially expressed proteins (DEPs) of 743 and 659, respectively. Functional annotation of DEPs revealed that the DEPs were primarily associated with stress response, hormone synthesis, photosynthesis, cell wall, and secondary metabolites. Notably, DEPs such as polyphenol oxidase, carboxypeptidase, heat shock proteins, protein BTR1-like isoform X2, chaperone protein ClpB1, and β glucosidase factors associated with environmental stress response were also detected. Quantitative real-time PCR (qRT-PCR) analysis confirmed a positive correlation between protein abundances and transcripts for all genes. Collectively, this study provides the molecular mechanisms associated with cotton defense responses against leaf hopper. Significance statementCotton, a natural fiber, assumes a pivotal role as a raw material for textile industries, thereby bearing significant importance in the global economy. The cotton production sector is considerably affected by both biotic and abiotic stresses. The cotton leaf hopper (Amrasca biguttula biguttula (Ishida)) stands as a polyphagous insect, emerging as a dominant sap-feeding pest of the cotton crop. The continuous onslaught of sap-feeding insects on cotton plants has a detrimental impact, with leaf hoppers potentially causing yield reductions of up to 50%. Therefore, comprehending the molecular interplay between cotton and leaf hopper, elucidated at the proteome level, holds promise for more effective pest management strategies. This approach holds the potential to offer insights that contribute to the development of leaf hopper-resistant cotton varieties.

Effectiveness study of the dual application of new Indigenous entomopathogenic nematode isolate Heterorhabditis taysearae and entomopathogenic fungi Beauveria bassiana against armyworm (Spodoptera frugiperda)

BackgroundThe fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a polyphagous insect pest species that travel great distances every summer to disperse. They mostly feed on maize and over 350 other crops. In this investigation, two entomopathogens: Beauveria bassiana and Heterorhabditis taysearae, were utilized to test the efficacy of each against S. frugiperda separately and then as a group by inoculating H. taysearae two days after fungal infection.ResultsEvaluations were done on mortality percentage, infective juvenile (IJ) production, and conidia production. The LT50 continually reduced with increases in nematode and fungus concentrations. For the LC50 value, the H. taysearae isolate was 289 IJs/larva after 96 h of treatment, while for B. bassiana isolate, it was 106 CFU/ml after 144 h of treatment. Dual infections with B. bassiana and H. taysearae had a beneficial effect on pest mortality, resulting in 83% mortality, and caused a significant increase in conidia production while utilizing the nematode or fungal separately caused decrease in mortality (63 and 73%, respectively).ConclusionsThe study’s findings indicated a quicker time to death and suggested that combining a moderately pathogenic fungal isolate with nematodes could raise the mortality rate. The mutually beneficial relationship between B. bassiana and H. taysearae controls S. frugiperda.

Two-Sex Life Table Analysis for Optimizing Beauveria bassiana Application against Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae).

Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) is a highly dispersive, polyphagous insect pest that severely defoliates crops. Excessive reliance on synthetic insecticides leads to ecological pollution and resistance development, urging scientists to probe eco-friendly biopesticides. Here, we explore the virulence of an entomopathogenic fungus, Beauveria bassiana, against S. exigua, resulting in 88% larval mortality. Using an age-stage, two-sex life table, we evaluated the lethal and sublethal effects of B. bassiana on the demographic parameters of S. exigua, including survival, development, and reproduction. Sublethal (LC20) and lethal concentrations (LC50) of B. bassiana impacted the parental generation (F0), with these effects further influencing the demographic parameters of the first filial generation (F1). The infected F1 offsprings showed a reduced intrinsic rate of increase (r), mean generation time (T), and net reproduction rate (R0). Larval developmental duration varied significantly between the control (10.98 d) and treated groups (LC20: 10.42; LC50: 9.37 d). Adults in the treated groups had significantly reduced lifespans (M: 8.22; F: 7.32 d) than the control (M: 10.00; F: 8.22 d). Reduced fecundity was observed in the B. bassiana-infected groups (LC20: 313.45; LC50: 223.92 eggs/female) compared to the control (359.55 eggs/female). A biochemical assay revealed elevated levels of detoxification enzymes (esterases, glutathione S-transferases, and acetylcholinesterase) in the F0 generation after B. bassiana infection. However, the enzymatic activity remained non-significant in the F1 generation likely due to the lack of direct fungal exposure. Our findings highlight the enduring effects of B. bassiana on the biological parameters and population dynamics of S. exigua, stressing its use in eco-friendly management programs.