Insect Pests Research Articles

Detection and functional validation of point mutations in acetylcholinesterase-1 associated with organophosphate resistance in field populations of Helicoverpa armigera.

Point mutations in the acetylcholinesterase-1 gene (ace-1) have been associated with resistance to OPs in many insects. However, the presence and function of ace-1 mutations associated with OP resistance in Helicoverpa armigera (Lepidoptera: Noctuidae), a significant lepidopteran pest damaging a wide range of crops, remain largely unexplored. This study investigated resistance to the OP insecticide phoxim in 12 field populations of H. armigera from northern China in 2022, revealing low levels of resistance (2.5- to 6.7-fold). Using an amplicon sequencing approach, we screened for ace-1 mutations in 13,874 moths collected from 114 populations collected between 2006 and 2022. We found 3 amino acid substitutions (A201S, G227E, and F290V) potentially related to OP resistance. The mean frequencies of A201S, G227E, and F290V mutations were 0.0032, 0.0001, and 0.0001, respectively. To assess these mutations' role in OP resistance, we expressed wild-type and mutant AChE1 proteins in Sf9 cells. Biochemical characterization revealed a 3.1-fold and 3.3-fold increase in the I50 of chlorpyrifos-oxon for A201S and F290V mutants compared to the wild-type enzyme, correlating with a 2.9-fold and 2.7-fold decrease in the Ki value. No enzyme activity was observed in the G227E mutant, indicating that only A201S and F290V confer insensitivity to chlorpyrifos-oxon. Our study demonstrates that amplicon sequencing is an effective method for large-scale screening of resistance-associated point mutations in field populations of H. armigera and potentially other insect pests. It also identifies A201S and F290V in AChE1 as potential point mutations conferring OP resistance in field populations of H. armigera.

Isolation and characterization of halophilic Bacillus thuringiensis from local Egyptian sites and their potential against Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

Abstract Background Bacillus thuringiensis (Bt) serves as a peculiar soil microbe that is Gram-positive, rod-shaped, spore-forming, and aerobic facultative. It endures across a range of conditions and has been demonstrated to be an effective biological pest control agent against several insect pests. The main objective of the study is to isolate and recognize Bt bacteria from saline environments in Egyptian soil for biological surveillance uses. Results Isolates three, four, five, ten, eleven, twelve, and thirteen were found to be moderately tolerant, while isolate eight showed highly tolerant, but isolate six was found to be borderline extreme halophile. On the other hand, the other isolates showed extreme halophiles. To find out the presence of crystals, a scanning electron microscope was carried out and the result showed that the crystals ranged from spherical to bi-pyramidal spherical. Molecular analysis was carried out using universal primers to confirm the presence of cry genes. The results showed that 84.6% of the isolates contain cry seven and eight, whereas cry one and four are distributed by 92.3%. Cry two genes were found to be 100 percent in all tested and isolated cultures. Cry genes were present and distribution among isolated was detected using gene-specific primers. cry3Ba1 and cry8B showed the lowest and equal distribution among the isolates, while the cry2Ab2gene frequency distribution was (84.6%) among isolated cultures. Around six cry genes were found to be absent in all isolated cultures. The bioinsecticidal activity and bioassays were carried out to check the potential effect of halophilic Bt isolates against 1st instar larvae of the Fall Armyworm (FAW) Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Mortality was calculated after infecting S. frugiperda with thirteen Bt isolates. The most virulent Bt isolate was isolate 7, followed by isolate 10, with LC50 values of 9.542 × 107 spores/ml and 1.289 × 108 spores/ml, respectively, after 72 h. Morphological traits of the larvae were carried out, to check the effect of Bt isolates as a biological control against the FAW. Conclusion To protect and enhance the sustainability of field crops and vegetables, especially in new high salinity lands, from disease-causing insects such as FAW, it is necessary to identify new strains of Bt from these saline lands. In this field, local isolates of Bt from several regions in Egypt known for their high levels of salinity were documented and showed an effective bioinsecticide on FAW larvae.

Cereal aphid species: their natural enemies and efficiency of Lysiphlebus testaceipes (Cresson, 1880) to control Rhopalosiphum maidis (Fitch, 1856)

AbstractCereal grains both for human consumption and animal feed are an essential component of global food systems. However, during production they are often targeted by various pest insects, including aphids. A survey was carried out from 2017 to 2021 in six cereal production sites in Tunisia to evaluate aphid diversity and identify natural enemies on Triticum turgidum subsp. durum (durum wheat), Hordeum vulgare (barley), Avena sativa (oat) and Triticum secale (triticale). Six aphid species belonging to four genera were recorded: Diuraphis noxia, Rhopalosiphum maidis, R. padi, Schizaphis graminum, Sitobion avenae and Sitobion fragariae. Among these, S. avenae and R. padi emerged as the most prevalent species across the majority of sites, infesting durum wheat, barley and triticale. Sc. graminum, R. maidis and D. noxia were less frequent, while S. fragariae was exclusively found on oat plants. Common aphid predators observed included Coccinella algerica, Hippodamia variegata and C. undecimpunctata, as well as syrphid flies such as Episyrphus balteatus and Sphaerophoria rueppellii. Lysiphlebus testaceipes was the sole parasitoid species detected, emerging exclusively from R. padi and R. maidis mummies. Furthermore, the study on the efficacy of L. testaceipes against R. maidis indicated that parasitism levels increased with the number of introduced parasitoid pairs. Aphid and natural enemy diversity were also evaluated.

Seven New Species of Anastatus Motschulsky (Hymenoptera: Chalcidoidea: Eupelmidae) from China Identified Based on Morphological and Molecular Data

Anastatus is the second-largest genus in the family Eupelmidae, with 150 species found worldwide and fourteen known species in China. Most species in this genus are the primary parasitoids of insect eggs, particularly those of Lepidoptera and Hemiptera, and several species have been used for the biological control of various insect pests. In this paper, seven new species of Anastatus Motschulsky, 1859 (Hymenoptera: Eupelmidae) from China are described, of which A. caeruleus Wang and Peng n. sp. and A. garygibsoni Zhou and Peng n. sp. were reared from the eggs of Tessaratoma papillosa (Hemiptera: Tessaratomidae), while A. daiyunensis Wang and Peng n. sp., A. makrysourus Zhou and Peng n. sp., A. polikiarkoudus Wang and Peng n. sp., A. taibaiensis Wang and Peng n. sp., and A. zdenekbouceki Zhou and Peng n. sp. were collected by malaise traps or sweeping. The new species are all described and illustrated based on female specimens, and the key to all 21 Chinese Anastatus species, based on females, is provided. Partial COI sequences of A. caeruleus n. sp., A. garygibsoni n. sp., and A. taibaiensis n. sp. are provided, and a phylogenetic reconstruction based on maximum likelihood analyses, while showing similar results at high taxonomic levels to our morphological feature classification results, provides additional information on the placement of Anastatus at the species level.

Analyses of Xenorhabdus griffiniae genomes reveal two distinct sub-species that display intra-species variation due to prophages.

Nematodes of the genus Steinernema and their Xenorhabdus bacterial symbionts are lethal entomopathogens that are useful in the biocontrol of insect pests, as sources of diverse natural products, and as research models for mutualism and parasitism. Xenorhabdus play a central role in all aspects of the Steinernema lifecycle, and a deeper understanding of their genomes therefore has the potential to spur advances in each of these applications. Here, we report a comparative genomics analysis of Xenorhabdus griffiniae, including the symbiont of Steinernema hermaphroditum nematodes, for which genetic and genomic tools are being developed. We sequenced and assembled circularized genomes for three Xenorhabdus strains: HGB2511, ID10 and TH1. We then determined their relationships to other Xenorhabdus and delineated their species via phylogenomic analyses, concluding that HGB2511 and ID10 are Xenorhabdus griffiniae while TH1 is a novel species. These additions to the existing X. griffiniae landscape further allowed for the identification of two subspecies within the clade. Consistent with other Xenorhabdus, the analysed X. griffiniae genomes each encode a wide array of antimicrobials and virulence-related proteins. Comparative genomic analyses, including the creation of a pangenome, revealed that a large amount of the intraspecies variation in X. griffiniae is contained within the mobilome and attributable to prophage loci. In addition, CRISPR arrays, secondary metabolite potential and toxin genes all varied among strains within the X. griffiniae species. Our findings suggest that phage-related genes drive the genomic diversity in closely related Xenorhabdus symbionts, and that these may underlie some of the traits most associated with the lifestyle and survival of entomopathogenic nematodes and their bacteria: virulence and competition. This study establishes a broad knowledge base for further exploration of not only the relationships between X. griffiniae species and their nematode hosts but also the molecular mechanisms that underlie their entomopathogenic lifestyle.

Survey on Influence of Cultural Practices on Banana Pseudostem Weevil, Odoiporus longicollis Olivier (Coleoptera: Curculionidae) Infestation in Major Banana Growing Districts of Northern Karnataka, India

The production and productivity of banana is governed by many biotic and abiotic factors. Among biotic factors, incidence of insect-pests is considered as one of the major impedimentin successful cultivation of banana. With respect to the Indian condition around eight pests commonly infest the banana crop. However, the banana pseudostem weevil Odoiporus longicollis is cosmopolite insect pest that threatens the banana cultivation. The most common management practices followed for managing this pest includes cultural practices. Diverse cultural practices have been communicated to and/or applied by resource-poor households over the past two decades to improve the overall farm health and crop tolerance to biotic/abiotic factors. Therefore, cultural practices are the only measures available to small-scale farmers for the control of banana pseudostem weevil. Hence the survey was conducted during 2020-21 to study the influence of cultural practices on O. longicollis infestation in major banana growing districts of north Karnataka. From the survey results on the cultural practices reveals that the pest severity was more severe on ratoon crop fields and the frequency recorded was 37.82%. However, the frequency recorded was 1.68% in first crop, wherein no pest infestation was recorded in main crop. Whereas, good number of farmers could not make a difference in infestation of pest between main and ratoon crop (60.50%) and in such fields infestation level was 4.11%. The banana farmers who were interacted mainly used suckers (36.13%) and tissue culture plants (36.13%) for planting followed by rhizome (24.37%), whereas few farmers used suckers and rhizomes (3.36%) for planting in a single piece of land. Accordingly, the per cent infestation of BPW was less when both tissue cultured plants (4.84%) and suckers (5.53%) used for planting. Whereas, infestation was more severe when both suckers and rhizomes were used (27.50%) on same piece of land and which was followed by rhizomes alone (16.00%).

Evaluating the attractiveness of different bait formulations for monitoring Liriomyza sativae (Diptera: Agromyzidae) adults

The growing need for sustainable agricultural practices drives the search for effective alternatives in pest management. Insects like Liriomyza sativae cause significant damage to crops, requiring monitoring and control methods that minimize the use of chemical pesticides. In this context, the use of natural and synthetic attractants for pest capture offers a promising solution while contributing to the preservation of ecological balance. The objective of this work was to study the attractive effect of different formulations for L. sativae adults. The formulations were divided into two groups according to their composition. For group 1, they were based on vinegar and sugar, and for group 2, formulations were based on molasses, invert sugar, hydrolyzed protein, and eugenold. The attractiveness of the formulations was evaluated based on free choice. They were placed in tube-shaped plastic containers and randomly arranged in TNT cages. Evaluations were performed every 48 hours by counting the number of adults in the containers until there was a low capture rate. Data were subjected to analysis of variance testing and means were compared using the Scott-Knott test at 5% significance level. All formulations tested were attractive to adults of L. sativae, with groups 1 and 2 reaching their maximum averages of 55.60 and 68.00 adults, respectively. Both occurred during the second evaluation. Over time, all formulations showed a reduction in capture rate. The use of effective attractants promotes traps that monitor and even control the pest population in a more sustainable way, benefiting the agroecosystem with sustainable agricultural practices. Furthermore, the research expands knowledge about the chemical ecology of insect pests, providing a basis for the chemical communication of these organisms.

Salivary effector DcE1 suppresses plant defense and facilitates the successful feeding of Asian citrus psyllid, Diaphorina citri.

Piercing-sucking insects secrete diverse repertoires of effectors into their hosts to weaken host defenses and promote infestation. The Asian citrus psyllid, Diaphorina citri Kuwayama, is the most destructive insect pest in citrus orchards because of its role as a vector for the huanglongbing pathogen, Candidatus Liberibacter asiaticus (CLas). However, specific effector proteins and their functions in D. citri remain unclear. We demonstrate that DcE1, a salivary protein gene from D. citri, is predominantly expressed in the salivary gland tissues and is delivered into host plants during feeding. Transient expression in tobacco leaves revealed that DcE1 was subcellularly localized in the cytoplasm and plasma membrane, where it inhibited BAX- and INF1-induced cell death, suppressed callose deposition, and activated the salicylic acid pathway by upregulating the expression of endo-β-1,3-glucanase NtBGL2 and regulatory protein NtNPR1. Further, DcE1 knockdown by double-stranded RNA (dsRNA) injection decreased the survival rates of D. citri and interrupted D. citri phloem-feeding on host plants. These results indicate that DcE1 is a novel effector that promotes plant susceptibility and enables D. citri feeding. These findings enhance our understanding of D. citri-plant interactions and offer a potential new target gene for the development of citrus protection strategies. © 2024 Society of Chemical Industry.

Efficacy and utility of isocycloseram a novel isoxazoline insecticide against urban pests and public health disease vectors.

Isoxazolines inhibit γ-aminobutyric acid chloride channels in insects and acarids by binding to postsynaptic receptors. This prevents chloride influx, leading to depolarization/hyperexcitation, paralysis, and death. Here, we evaluated the potential utility of a novel isoxazoline, isocycloseram, against several urban insect pests. Isocycloseram was active at low doses against the German cockroach, Blattella germanica (L.)[median lethal dose (LD50) 5-15 ng per insect at 72 h, topical assays]; Argentine ant (Linepithema humile Mayr), Pharaoh ant (Monomorium pharaonis (L.), common bed bug (Cimex lectularius (L.) (approximately 40 mg m-2, residual surface spray); Eastern subterranean termite (Reticulitermes flavipes (Kollar)and Formosan subterranean termite (Coptotermes formosanus Shiraki) (5 μg g-1 w/w, tunneling assays); and mosquito, Anopheles stephensi Liston (120 and 150 mg m-2 treated surfaces, aged indoors for 9 months). Additionally, cockroach gel bait at 1% isocycloseram (w/w) caused 95-100% mortality in German, American (Periplaneta americana (L.), and oriental (Blatta orientalis (L.) cockroaches within 5-14 days. Isocycloseram proved to be active against both laboratory and field populations of German cockroaches at doses lower or equal to those of other chemicals. Ants, bed bugs, and mosquitoes readily acquired lethal doses of isocycloseram from different surfaces treated with formulated products. Given its non-repellent nature, delayed effects, and activity at low rates, isocycloseram can be a very effective compound against subsocial, social, and other human disease vector insect pests. © 2024 Society of Chemical Industry.

Sublethal effects of neonicotinoids on insect pests

Sublethal effects of neonicotinoids on insect pests

Bio-fumigants as grain protectants in storage-A review

Agriculture is a global lifeline, especially in developing nations like India, where over 70% of the population relies on it. Protecting food grains from insect pests during post-harvest storage is crucial, particularly in regions lacking advanced storage technologies, leading to significant losses. Fumigation is still a key strategy for safeguarding stored grains. Methyl bromide (MBr) and aluminium phosphide (AlP) are the widely used chemical fumigants. Phosphine is used to a greater extent today, but there are frequent reports that several storage pests have developed resistance to this fumigant. The United Nations World Meteorological Organization declared methyl bromide as an ozone-depleting chemical in 1995, and hence, most of the developed countries have phased out its use. Therefore, there is an urgent requirement to develop alternatives having a possible replacement for these fumigants. Biofumigants are organic compounds derived from various plant sources, including essential oils, botanical powders, and plant residues or from microbial volatiles. They release volatile compounds toxic to pests but safe for humans and the environment, offering a sustainable pest management approach. Plants such as mustard and radish produce glucosinolates that release isothiocyanates, known for their pesticidal properties. Essential oils from eucalyptus, clove, and mint and volatiles from certain fungi and bacteria also exhibit fumigant properties. Biofumigants disrupt insect physiological and biochemical processes, leading to mortality or reduced reproduction. Studies showed their efficacy against pests like red flour beetle, lesser grain borer, and rice weevil. Unlike chemical fumigants, biofumigants do not leave harmful residues, preserving grain quality and aligning with organic farming practices. Shifting to biofumigants offers a promising, eco-friendly, and effective alternative for post-harvest pest management, ensuring food safety and sustainability

Decoding plant defense: accelerating insect pest resistance with omics and high-throughput phenotyping

Decoding plant defense: accelerating insect pest resistance with omics and high-throughput phenotyping

Identification of a vital transcription factor of the alanine aminotransferase in the brown planthopper and its upstream regulatory pathways.

The brown planthopper (Nilaparvata lugens) is an important insect pest of rice, and can rapidly adapt to insect-resistant rice varieties. In our previous studies, alanine aminotransferase in N. lugens (NlALT) was found to play an important role in the adaptation of the brown planthopper to resistant rice IR36. Here, we further identified CCAAT/enhancer binding protein (NlC/EBP) as a vital transcription factor of NlALT. Nlp38b in the MAPKs pathway regulated the expression of NlALT by influencing the phosphorylation level of NlC/EBP. In addition, we found that NlGRL101, a G protein-coupled receptor (GPCR), was significantly higher expressed in the N. lugens population adapted to IR36 (P-IR36). After knockdown of NlGRL101 through RNAi in P-IR36 population, lower expressions of Nlp38b and NlC/EBP, along with reduced phosphorylation levels of Nlp38b and NlC/EBP were observed; moreover, NlALT activity and honeydew amount were decreased by 15.68% and 76.08%, respectively. These results indicated that insect-resistant rice IR36 induced expression of NlGRL101, which enhanced expression of NlALT through Nlp38b and NlC/EBP. These findings are helpful for better understanding of insect adaptation to resistant crop varieties.

Plant-Guided Microbiome Selection Produces Transient Effects on Insect Performance and Rhizosphere Community Assembly

Microbial communities are essential for plant health, but using these relationships to enhance growth and pest protection is challenging. Leveraging the natural mechanisms plants employ to manage relationships with microbes is one promising means to selectively engineer whole microbial communities with beneficial properties. This approach, known as host-guided selection, has been successful in some model species targeting performance traits (e.g., biomass). However, few studies use crop plants or focus on defensive traits (e.g., pest resistance). Our goal was to naturally engineer tomato root-associated microbiomes that increase resistance to insect pests. First, we used an iterative soil microbial inoculation process to engineer insect-suppressive rhizosphere soil microbiomes that reduce damage from aphid feeding ( Macrosiphum euphorbiae) or caterpillar defoliation ( Manduca sexta, Spodoptera exigua). We then characterized the bacterial and fungal microbial communities of soils associated with differences in insect performance using metabarcoding approaches. Overall, soil microbiome selection produced transient differences in aphid performance, but caterpillar growth was unaffected. In four of nine generations, the aphid population growth rate was significantly lower on plants with rhizospheres selected for “low” insect performance, where abundance was reduced by up to 20%. Correspondingly minor shifts in fungal and bacterial relative abundance occurred in insect-suppressive communities. However, network analysis indicated that aphid feeding disrupted rhizosphere microbiome assembly, resulting in lower community complexity and connectivity and fewer structurally important taxa compared with uninfested controls. Overall, our results highlight critical factors for successful engineering of beneficial microbiomes, particularly insect feeding guild and microbial community stability.

Adhesive traps for suppressing pest insects represent a serious threat to bats across Europe

Adhesive traps for suppressing pest insects represent a serious threat to bats across Europe

Overview of Brinjal (Solanum melongena L.) Pests and Their Management: A Review

Brinjal (eggplant or aubergine), a widely cultivated vegetable in tropical and subtropical regions, faces significant threats from a variety of insect pests. These pests cause substantial damage at different stages of crop growth, leading to reduced yields and compromised fruit quality. This review provides a comprehensive overview on the major insect pests that affect brinjal cultivation, focusing on their biology, damage mechanisms, and current management practices. Special emphasis is placed on integrated pest management (IPM) strategies, combining cultural, biological and chemical control methods to promote sustainable brinjal production.

Impact of Key Insect Pests on Cowpea and their Relationship with Weather Parameters

Introduction: Cowpea (Vigna unguiculata L.) is a vital pulse crop with substantial nutritional value in India that faces production challenges due to various biotic and abiotic factors. Among the biotic factors that affects cowpea, pests such as Maruca vitrata and Riptortus pedestris significantly impact cowpea yields. This study aimed to evaluate the seasonal incidence of these pests and analyze their correlations with weather parameters in Thiruvananthapuram, Kerala. Methodology: Field observations were conducted over the cropping season to record pest populations across Standard Meteorological Weeks (SMWs). The population of the pod bugs and pod borers were taken from five plants. Statistical analyses were performed to identify correlations between pest incidence and key weather factors. Key Findings: The incidence of R. pedestris peaked in the 16th SMW, reaching 7.54 bugs per five plants. This pest displayed a significant positive correlation with maximum temperature (r = 0.637) and minimum temperature (r = 0.559) and a negative correlation with evening relative humidity (r =-0.480). Similarly, M. vitrata larval populations peaked during the same period at 2.65 larvae per five plants, showing a similar temperature-dependent correlation. Implications: The temperature-sensitive incidence patterns observed underscore the need for integrated pest management (IPM) strategies that address climatic factors to enhance cowpea sustainability. This data provides valuable insights for future pest forecasting and management efforts.

Green guardians: Harnessing biopesticides for sustainable vegetable pest management

Insect pests pose significant challenges to vegetable crops, causing not only economic losses but also compromising the quality of our food. Shockingly, up to 20 % of globally produced goods fall victim to these insidious invaders. While chemical insecticides have historically bolstered food production, they come with notable drawbacks, including handling risks, residue concerns and negative impacts on non-target species and the environment.Though they have not yet completely replaced chemical insecticides, biopesticides are becoming key in reducing pesticide overuse and promoting safer, residue-free food and environments. Derived from plants and microorganisms, biopesticides offer a safer alternative, ranging from plant extracts to microbial agents such as bacteria, fungi, viruses and nematodes. Additionally, insect hormones and semiochemicals, along with silica-based mineral products like activated clay and rice husk, contribute to eco-friendly pest control solutions. Cutting-edge nano biopesticides also deliver unparalleled pest control with precision targeting and excellent environmental credentials.In this comprehensive exploration, we delve deep into the myriad forms of biopesticides, their commercial availability, modes of action and the advantages and disadvantages in vegetable pest management. Crucially, we illuminate the path toward integrating biopesticides into holistic pest management strategies, which can lead to healthier crops, increased yields and more sustainable agricultural practices. By emphasizing biopesticides, we can promote environmental safety and support a greener future in agriculture.

A Low-Cost Remotely Configurable Electronic Trap for Insect Pest Dataset Generation

The precise monitoring of insect pest populations is the foundation of Integrated Pest Management (IPM) for pests of plants, humans, and animals. Digital technologies can be employed to address one of the main challenges, such as reducing the IPM workload and enhancing decision-making accuracy. In this study, digital technologies are used to deploy an automated trap for capturing images of insects and generating centralized repositories on a server. Subsequently, advanced computational models can be applied to analyze the collected data. The study provides a detailed description of the prototype, designed with a particular focus on its remote reconfigurability to optimize repository quality; and the server, accessible via an API interface to enhance system interoperability and scalability. Quality metrics are presented through an experimental study conducted on the constructed demonstrator, emphasizing trap reliability, stability, performance, and energy consumption, along with an objective analysis of image quality using metrics such as RMS contrast, Image Entropy, Image sharpness metric, Natural Image Quality Evaluator (NIQE), and Modulation Transfer Function (MFT). This study contributes to the optimization of the current knowledge regarding automated insect pest monitoring techniques and offers advanced solutions for the current systems.

What Can Insects Tell Us About Crimes?

Have you ever considered how important insects are in almost all of Earth’s ecosystems? Beyond their well-known roles as pollinators, decomposers, and control of other insect pests, did you know that insects can also play a vital role in solving crimes? In this article, we explore fascinating examples of how entomologists (scientists who study insects) can assist law enforcement and the justice system by using insects to crack real criminal cases. By studying the life cycle, ecology, and behavior of insects found at crime scenes, entomologists can provide critical information on the timing and circumstances of a person’s death, determine when a food became contaminated, or figure out how and when a home insect infestation occurred. Prepare to delve into the world of forensic entomology, where you will discover how these tiny creatures contribute to the pursuit of justice.