Insect Host Research Articles

Species of Laboulbeniales fungi parasitic on some common Indian insects: Isolation, visualization and characterization by Scanning Electron Micrographs (SEM)

The Laboulbeniales are a group of lesser-known fungi. They occur as ectoparasites on the exoskeleton of various arthropod species, mainly beetles, cockroaches, ants, dipterans and a few millipede genera appearing as hairs/bristles coming out of their cuticle. They are small, non-mycelial fungi forming compact multicellular thalli, starting from a two-celled sheathed ascospore which continues to envelop the mature thallus. The fungi, being obligate, spend their entire life cycle on their insect hosts. The present study attempted to locate the Laboulbeniales fungi in the common insects of India, isolate them and identify them based on morphology. Different species of insects; Carabid beetles - Stenolophus sp., Bembidion sp., Black ants - Camponotus sp., and Earwigs - Labidura riparia; were collected from different habitats of damp garden soil, river banks, light sources and entomological collection museum situated as different sites New Delhi. The insects were scrutinized for the presence of fungi through light and scanning electron microscopy. The morphological features of each fungus were recorded, and the species were characterized. The studies showed the presence of Laboulbenia anaplogenii and L. stenolophi on the legs of Stenolophus sp.; L. egens on Bembidion sp. legs; L. camponoti on the wings of black ants and Dimeromyces anisolabis on the legs of earwigs. The identification was made primarily based on the size, shape and structure of basal foot, receptacles, antheridia and foot of the thallus or it’s remnant scar found on the insect cuticle. This is the first Indian report of conducting scanning imaging of the Laboulbeniales fungi.

Diversity of Hymenopteran Parasitoids in different Crop Ecosystems

Surveys were carried out in different districts viz., Shivamogga, Davangere and Chitradurga of Karnataka to collect and document hymenopteran parasitoids parasitizing insect pests attacking different crop ecosystems. A total of 42 hymenopteran parasitoids species represented by 33 genera belonged 12 families were documented from a collection of 1379 specimens from different stages viz., egg, larva, pupa and adult stage of host insects from different host plants viz., rice, maize, cabbage, cotton, coconut, brinjal, cashew, crape jasmine, tobacco, field bean, soybean, arecanut, cocoa, okra and pongamia. Among them, maximum parasitoids species (20) were collected from larval stage of host insects with per cent species composition of 47.62. Among the families, Braconidae was found most dominant (comprised of 23.81%), followed by Eulophidae (16.67%), Encyrtidae and Scelionidae (each with 14.29%). Alpha and beta diversity were computed for the three zones. Species diversity in terms of richness, evenness and abundance of hymenopteran parasitoids were calculated and compared during study period using Shannon-Wiener index, Simpson diversity index, Margalef’s diversity index, Menhinick’s index and Evenness. Species diversity was high in Shivamogga district as evidenced by Shannon-Wiener index (2.49), Simpson diversity index (0.88), Margalef’s index (4.09) and Menhinick’s index (1.22) and Evenness (0.46), followed by Davanagere district with respect to Shannon-Wiener index (1.69) Simpson’s diversity index (0.75), Margalef’s index and Menhinick’s index (2.27 and 0.90), respectively, while evenness was 0.24 and Chitradurga district with respect to Shannon-Wiener index (1.34) Simpson’s diversity index (0.54), Margalef’s index and Menhinick’s index (2.12 and 0.59), respectively.

Study on metabolic response of female and male Trogoderma varia-bile (Ballion) on different host grain using direct immersion solid-phase microextraction coupled with gas chromatography mass

The purpose of this study is to use the technique of gas chromatography coupled with mass spectrometry to study the metabolite profile of Trogoderma variabile using different host grains including canola, oats, wheat, and barley. Also, hydrocarbon profiling can be used as a chemo-taxonomical tool for insect species identification, especially for very morphologically similar species like T. granarium. For sample preparation insects were subjected to extraction with acetonitrile. Direct Immersion-Solid Phase Microextraction (DI-SPME) was employed, followed by Gas Chromatography-Mass Spectrometry analysis (GC-MS) for the collection, separation, and identification of compounds. Additionally, insect host grains have a significant effect on the insect chemicals that are identified from T. variabile adults such as fatty acid and hydrocarbons. Results showed that insect host grains have a significant influence on the chemical compounds that are identified in females and males. There were twenty-three compounds were identified from adults reared on canola and wheat. However, there were 26 and 28 compounds detected from adults reared on oats and barley respectively. Results also showed that 11-methylpentacosane; 13-methylheptacosane; heptacosane; docosane, 1-iodo- and nonacosane were the most significant compounds that identified form T. variabile male reared on different host grains. However, the main compounds identified from female cultured on different host grains include docosane, 1-iodo-; 1-butylamine, N-butyl-; oleic acid; heptacosane; 13-methylheptacosane; hexacosane; nonacosane; 2-methyloctacosane; n-hexadecanoic acid and docosane in the female samples.

Oxidative stress is intrinsic to staphylococcal adaptation to fatty acid synthesis antibiotics

Antibiotics inhibiting the fatty acid synthesis pathway (FASII) of the major pathogen Staphylococcus aureus reach their enzyme targets, but bacteria continue growth by using environmental fatty acids (eFAs) to produce phospholipids. We assessed the consequences and effectors of FASII-antibiotic (anti-FASII) adaptation. Anti-FASII induced lasting expression changes without genomic rearrangements. Several identified regulators affected the timing of adaptation outgrowth. Adaptation resulted in decreased expression of major virulence factors. Conversely, stress responses were globally increased and adapted bacteria were more resistant to peroxide killing. Importantly, pre-exposure to peroxide led to faster anti-FASII-adaptation by stimulating eFA incorporation. This adaptation differs from reports of peroxide-stimulated antibiotic efflux, which leads to tolerance. Invivo, anti-FASII-adapted S.aureus killed the insect host more slowly but continued multiplying. We conclude that staphylococcal adaptation to FASII antibiotics involves reprogramming, which decreases virulence and increases stress resistance. Peroxide, produced by the host to combat infection, favors anti-FASII adaptation.

Bactericera cockerelli Picorna-like Virus and Three New Viruses Found Circulating in Populations of Potato/Tomato Psyllids (Bactericera cockerelli).

An investigation of viruses circulating in populations of field and laboratory potato/tomato psyllids (Bactericera cockerelli) was conducted using high-throughput sequencing (HTS) technology and conventional RT-PCR. Three new viruses were discovered: one from the family Tymoviridae and two from the family Solemoviridae. A tymo-like virus sequence represented a nearly complete 6843 nt genome of a virus named Bactericera cockerelli tymo-like virus (BcTLV) that spanned five open reading frames (ORFs) which encoded RNA-dependent RNA polymerase (RdRP), helicase, protease, methyltransferase, and a capsid protein. Phylogenetic analyses placed the RdRP of BcTLV inside a divergent lineage of the viruses from the family Tymoviridae found in insect and plant hosts in a sister clade to the genera Tymovirus, Marafivirus, and Maculavirus. Four solemo-like virus sequences were identified in the HTS outputs, representing two new viruses. One virus found only in field-collected psyllids and named Bactericera cockerelli solemo-like virus 1 (BcSLV-1) had a 5479 nt genome which spanned four ORFs encoding protease and RdRP. Three solemo-like sequences displayed 87.4-99.7% nucleotide sequence identity among themselves, representing variants or strains of the same virus named Bactericera cockerelli solemo-like virus 2 (BcSLV-2). The genome of BcSLV-2 spanned only two ORFs that encoded a protease and an RdRP. Phylogenetic analysis placed the RdRPs of BcSLV-1 and BcSLV-2 in two separate lineages as sister clades to viruses from the genus Sobemovirus found in plant hosts. All three new psyllid viruses were found circulating in psyllids collected from potato fields in southern Idaho along with a previously identified Bactericera cockerelli picorna-like virus. Any possible role of the three viruses in controlling populations of the field psyllids remains to be elucidated.

A viral movement protein targets host catalases for 26S proteasome-mediated degradation to facilitate viral infection and aphid transmission in wheat

The infection of host plants by many different viruses causes reactive oxygen species (ROS) accumulation and yellowing symptoms, but the mechanisms through which plant viruses counteract ROS-mediated immunity to facilitate infection and symptom development have not been fully elucidated. Most plant viruses are transmitted by insect vectors in the field, but the molecular mechanisms underlying virus‒host–insect interactions are unclear. In this study, we investigated the interactions among wheat, barley yellow dwarf virus (BYDV), and its aphid vector and found that the BYDV movement protein (MP) interacts with both wheat catalases (CATs) and the 26S proteasome ubiquitin receptor non-ATPase regulatory subunit 2 homolog (PSMD2) to facilitate the 26S proteasome-mediated degradation of CATs, promoting viral infection, disease symptom development, and aphid transmission. Overexpression of the BYDV MP gene in wheat enhanced the degradation of CATs, which leading to increased accumulation of ROS and thereby enhanced viral infection. Interestingly, transgenic wheat lines overexpressing BYDV MP showed significantly reduced proliferation of wingless aphids and an increased number of winged aphids. Consistent with this observation, silencing of CAT genes also enhanced viral accumulation and reduced the proliferation of wingless aphids but increased the occurrence of winged aphids. In contrast, transgenic wheat plants overexpressing TaCAT1 exhibited the opposite changes and showed increases in grain size and weight upon infection with BYDV. Biochemical assays demonstrated that BYDV MP interacts with PSMD2 and promotes 26S proteasome-mediated degradation of TaCAT1 likely in a ubiquitination-independent manner. Collectively, our study reveals a molecular mechanism by which a plant virus manipulates the ROS production system of host plants to facilitate viral infection and transmission, shedding new light on the sophisticated interactions among viruses, host plants, and insect vectors.

A CTL − Lys immune function maintains insect metamorphosis by preventing gut bacterial dysbiosis and limiting opportunistic infections

BackgroundGut bacteria are beneficial to the host, many of which must be passed on to host offspring. During metamorphosis, the midgut of holometabolous insects undergoes histolysis and remodeling, and thus risks losing gut bacteria. Strategies employed by holometabolous insects to minimize this risk are obscure. How gut bacteria affect host insects after entering the hemocoel and causing opportunistic infections remains largely elusive.ResultsWe used holometabolous Helicoverpa armigera as a model and found low Lactobacillus load, high level of a C-type lectin (CTL) gene CD209 antigen-like protein 2 (CD209) and its downstream lysozyme 1 (Lys1) in the midgut of the wandering stage. CD209 or Lys1 depletion increased the load of midgut Lactobacillus, which further translocate to the hemocoel. In particular, CD209 or Lys1 depletion, injection of Lactobacillus plantarum, or translocation of midgut L. plantarum into the hemocoel suppressed 20-hydroxyecdysone (20E) signaling and delayed pupariation. Injection of L. plantarum decreased triacylglycerol and cholesterol storage, which may result in insufficient energy and 20E available for pupariation. Further, Lysine-type peptidoglycan, the major component of gram-positive bacterial cell wall, contributed to delayed pupariation and decreased levels of triacylglycerols, cholesterols, and 20E, in both H. armigera and Drosophila melanogaster.ConclusionsA mechanism by which (Lactobacillus-induced) opportunistic infections delay insect metamorphosis was found, namely by disturbing the homeostasis of lipid metabolism and reducing 20E production. Moreover, the immune function of CTL − Lys was characterized for insect metamorphosis by maintaining gut homeostasis and limiting the opportunistic infections.

Frequent horizontal chromosome transfer between asexual fungal insect pathogens

Entire chromosomes are typically only transmitted vertically from one generation to the next. The horizontal transfer of such chromosomes has long been considered improbable, yet gained recent support in several pathogenic fungi where it may affect the fitness or host specificity. To date, it is unknown how these transfers occur, how common they are, and whether they can occur between different species. In this study, we show multiple independent instances of horizontal transfers of the same accessory chromosome between two distinct strains of the asexual entomopathogenic fungus Metarhizium robertsii during experimental co-infection of its insect host, the Argentine ant. Notably, only the one chromosome-but no other-was transferred from the donor to the recipient strain. The recipient strain, now harboring the accessory chromosome, exhibited a competitive advantage under certain host conditions. By phylogenetic analysis, we further demonstrate that the same accessory chromosome was horizontally transferred in a natural environment between M. robertsii and another congeneric insect pathogen, Metarhizium guizhouense. Hence, horizontal chromosome transfer is not limited to the observed frequent events within species during experimental infections but also occurs naturally across species. The accessory chromosome that was transferred contains genes that may be involved in its preferential horizontal transfer or support its establishment. These genes encode putative histones and histone-modifying enzymes, as well as putative virulence factors. Our study reveals that both intra- and interspecies horizontal transfer of entire chromosomes is more frequent than previously assumed, likely representing a not uncommon mechanism for gene exchange.

Wolbachia Interactions with Diverse Insect Hosts: From Reproductive Modulations to Sustainable Pest Management Strategies.

Effective in a variety of insect orders, including dipteran, lepidopteran, and hemipteran, Wolbachia-based control tactics are investigated, noting the importance of sterile and incompatible insect techniques. Encouraging approaches for controlling Aedes mosquitoes are necessary, as demonstrated by the evaluation of a new SIT/IIT combination and the incorporation of SIT into Drosophila suzukii management. For example, Wolbachia may protect plants from rice pests, demonstrating its potential for agricultural biological vector management. Maternal transmission and cytoplasmic incompatibility dynamics are explored, while Wolbachia phenotypic impacts on mosquito and rice pest management are examined. The importance of host evolutionary distance is emphasised in recent scale insect research that addresses host-shifting. Using greater information, a suggested method for comprehending Wolbachia host variations in various contexts emphasises ecological connectivity. Endosymbionts passed on maternally in nematodes and arthropods, Wolbachia are widely distributed around the world and have evolved both mutualistic and parasitic traits. Wolbachia is positioned as a paradigm for microbial symbiosis due to advancements in multiomics, gene functional assays, and its effect on human health. The challenges and opportunities facing Wolbachia research include scale issues, ecological implications, ethical conundrums, and the possibility of customising strains through genetic engineering. It is thought that cooperative efforts are required to include Wolbachia-based therapies into pest management techniques while ensuring responsible and sustainable ways.

Standardization of Formulation and Application Approaches for Field Implementation of EPNs

Entomopathogenic nematodes (EPNs) live parasitically inside the infected insect host, and so they are termed as endoparasitic. They infect different types of insect living in the soil like the larval forms of moths, butterflies and beetles as well as adult forms of beetles, grasshoppers and crickets. The present experiment was conducted under both laboratory and field conditions at CCS Haryana Agriculture University, Hisar. Two most virulent strains of EPNs, Metarhabditis amsactae strain HAR-St-II and HAR-Ht-III were taken and their formulations were standardized using six different media i.e. cadaver based formulation, water, alginate gel, foam chips, clay chips and water dispersible granules. Among these formulations, cadaver based formulation was found to be best. Maximum numbers of active IJs after 90 days were obtained from this formulation were 3370 and 2728 /Petri plate in strain HAR-St-II and HAR- Ht-III of M. amsactae, respectively. Further this, experiment was conducted at field level for EPNs suspension was standardized using different size of nozzle opening i.e. 25 µm, 50 µm, 75 µm and 100 µm on knapsack sprayer. Spodoptera litura was selected as a test insect in okra crop for foliar application of EPNs and results revealed that 100 µm nozzle opening size gave maximum larval mortality of S. litura. Per cent mortality of S. litura was increased with increase in size of nozzle and period of observation

Fights on the surface prior to fungal invasion of insects.

Entomopathogenic fungi (EPF) infect insects by landing on and penetrating cuticles. Emerging evidence has shown that, prior to the invasion of insects, fungal cells have to battle and overcome diverse challenges, including the host behavioral defenses, colonization resistance mediated by ectomicrobiotas, host recognition, and generation of enough penetration pressure. The ascomycete EPF such as Metarhizium and Beauveria can thus produce adhesive proteins and/or the exopolysaccharide mucilage to tightly glue fungal cells on cuticles. Producing antimicrobial peptides and chemical compounds can enable EPF to outcompete cuticular defensive microbes. The use of divergent membrane receptors, accumulation, and quick degradation of lipid droplets in conidial cells can help EPF recognize proper hosts and build up cellular turgor to breach cuticles for systematic invasion. Further investigations are still required to unveil the multifaceted and intricate relationships between EPF and insect hosts.

Effects of thiamethoxam on physiological and molecular responses to potato plant (Solanum tuberosum), green peach aphid (Myzus persicae), and parasitoid (Aphidius gifuensis).

To improve integrated pest management (IPM) performance it is essential to assess pesticide side effects on host plants, insect pests, and natural enemies. The green peach aphid (Myzus persicae Sulzer) is a major insect pest that attacks various crops. Aphidius gifuensis is an essential natural enemy of M. persicae that has been applied effectively in controlling M. persicae. Thiamethoxam is a neonicotinoid pesticide widely used against insect pests. The current study showed the effect of thiamethoxam against Solanum tuberosum, M. persicae, and A. gefiuensis and the physiological and molecular response of the plants, aphids, and parasitoids after thiamethoxam application. Thiamethoxam affected the physical parameters of S. tuberosum and generated a variety of sublethal effects on M. persicae and A. gefiuensis, including nymph development time, adult longevity, and fertility. Our results showed that different thiamethoxam concentrations [0.1, 0.5, and 0.9 μm active ingredient (a.i.)/L] on different time durations (2, 6, and 10 days) increased the antioxidant enzyme activities SOD, POD, and CAT of S. tuberosum, M. persicae, and A. gefiuensis significantly compared with the control. Our results also showed that different thiamethoxam concentrations (0.1, 0.5, and 0.9 μm a.i./L) on different time durations (2, 6, and 10 days) increased the expression of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), acetylcholinesterase (AChE), carboxylesterase (CarE) and glutathione-S-transferase (GST) genes of S. tuberosum, M. persicae, and A. gefiuensis compared with the control. Our findings reveal that using thiamethoxam at suitable concentrations and time durations for host plants and natural enemies may enhance natural control through the conservation of natural enemies by overcoming any fitness disadvantages. © 2024 Society of Chemical Industry.

Thiourea as a polyphenol oxidase inhibitor enhances host infection by the entomopathogenic nematode, Heterorhabditis beicherriana

Entomopathogenic nematodes (EPN) are potent microbial biocontrol agents applied commercially against various economically important insect pests. The efficacy of EPN in the field may be partially reduced when compared to chemical insecticides due to its sensitivity to environmental stressors like temperature, desiccation, and UV light. Thus, researchers have developed methods to enhance the effectiveness of EPN, such as screening or breeding stress-resistant strains and creating adjuvants for EPN protection in the field. This study used another strategy to lower the host’s immunity so that the anti-infection ability of the pest wanes, and the virulence of EPN waxes accordingly. In addition to its use as a plant growth regulator, thiourea also functions as an inhibitor of polyphenol oxidase (PO) in insects. Thiourea can inhibit a key interaction in the humoral immunity of insects, so we utilized it to enhance the efficacy of EPN. To investigate the effects of thiourea on PO activity inhibition and EPN pathogenesis, we studied the effects of thiourea on survival, infectivity, reproduction, and host searching ability of the EPN, Heterorhabditis beicherriana, and monitored in vivo and in vitro polyphenol oxidase activity of the model insect host, Galleria mellonella. The survival of H. beicherriana infective juveniles (IJs) was barely affected after exposure to 0.5 mM and 1 mM thiourea solution, and the reproductive output of H. beicherriana IJs (after applying 50, 100 and 200 IJs per host) in 0.5 mM and 1 mM thiourea was not different compared to the control. However, the LD50 of G. mellonella larvae caused by H. beicherriana without thiourea was significantly higher than H. beicherriana IJs in thiourea. Moreover, thiourea inhibited in vivo and in vitro polyphenol oxidase activity of G. mellonella infected by EPNs at different concentrations. Thus, thiourea can improve the biological control efficacy of EPNs, and the enhanced environmentally friendly approach may apply to diverse cropping systems.

Functional and Compositional Changes in Sirex noctilio Gut Microbiome in Different Habitats: Unraveling the Complexity of Invasive Adaptation.

The mutualistic symbiosis relationship between the gut microbiome and their insect hosts has attracted much scientific attention. The native woodwasp, Sirex nitobei, and the invasive European woodwasp, Sirex noctilio, are two pests that infest pines in northeastern China. Following its encounter with the native species, however, there is a lack of research on whether the gut microbiome of S. noctilio changed, what causes contributed to these alterations, and whether these changes were more conducive to invasive colonization. We used high-throughput and metatranscriptomic sequencing to investigate S. noctilio larval gut and frass from four sites where only S. noctilio and both two Sirex species and investigated the effects of environmental factors, biological interactions, and ecological processes on S. noctilio gut microbial community assembly. Amplicon sequencing of two Sirex species revealed differential patterns of bacterial and fungal composition and functional prediction. S. noctilio larval gut bacterial and fungal diversity was essentially higher in coexistence sites than in separate existence sites, and most of the larval gut bacterial and fungal community functional predictions were significantly different as well. Moreover, temperature and precipitation positively correlate with most of the highly abundant bacterial and fungal genera. Source-tracking analysis showed that S. noctilio larvae at coexistence sites remain dependent on adult gut transmission (vertical transmission) or recruitment to frass (horizontal transmission). Meanwhile, stochastic processes of drift and dispersal limitation also have important impacts on the assembly of S. noctilio larval gut microbiome, especially at coexistence sites. In summary, our results reveal the potential role of changes in S. noctilio larval gut microbiome in the successful colonization and better adaptation of the environment.

Genome Sequence Analysis of Native Xenorhabdus Strains Isolated from Entomopathogenic Nematodes in Argentina.

Entomopathogenic nematodes from the genus Steinernema (Nematoda: Steinernematidae) are capable of causing the rapid killing of insect hosts, facilitated by their association with symbiotic Gram-negative bacteria in the genus Xenorhabdus (Enterobacterales: Morganellaceae), positioning them as interesting candidate tools for the control of insect pests. In spite of this, only a limited number of species from this bacterial genus have been identified from their nematode hosts and their insecticidal properties documented. This study aimed to perform the genome sequence analysis of fourteen Xenorhabdus strains that were isolated from Steinernema nematodes in Argentina. All of the strains were found to be able of killing 7th instar larvae of Galleria mellonella (L.) (Lepidoptera: Pyralidae). Their sequenced genomes harbour 110 putative insecticidal proteins including Tc, Txp, Mcf, Pra/Prb and App homologs, plus other virulence factors such as putative nematocidal proteins, chitinases and secondary metabolite gene clusters for the synthesis of different bioactive compounds. Maximum-likelihood phylogenetic analysis plus average nucleotide identity calculations strongly suggested that three strains should be considered novel species. The species name for strains PSL and Reich (same species according to % ANI) is proposed as Xenorhabdus littoralis sp. nov., whereas strain 12 is proposed as Xenorhabdus santafensis sp. nov. In this work, we present a dual insight into the biocidal potential and diversity of the Xenorhabdus genus, demonstrated by different numbers of putative insecticidal genes and biosynthetic gene clusters, along with a fresh exploration of the species within this genus.

Aspartyl protease in the secretome of honey bee trypanosomatid parasite contributes to infection of bees

BackgroundThe exoproteome, which consists of both secreted proteins and those originating from cell surfaces and lysed cells, is a critical component of trypanosomatid parasites, facilitating interactions with host cells and gut microbiota. However, its specific roles in the insect hosts of these parasites remain poorly understood.MethodsWe conducted a comprehensive characterization of the exoproteome in Lotmaria passim, a trypanosomatid parasite infecting honey bees, under culture conditions. We further investigated the functions of two conventionally secreted proteins, aspartyl protease (LpAsp) and chitinase (LpCht), as representative models to elucidate the role of the secretome in L. passim infection of honey bees.ResultsApproximately 48% of L. passim exoproteome proteins were found to share homologs with those found in seven Leishmania spp., suggesting the existence of a core exoproteome with conserved functions in the Leishmaniinae lineage. Bioinformatics analyses suggested that the L. passim exoproteome may play a pivotal role in interactions with both the host and its microbiota. Notably, the deletion of genes encoding two secretome proteins revealed the important role of LpAsp, but not LpCht, in L. passim development under culture conditions and its efficiency in infecting the honey bee gut.ConclusionsOur results highlight the exoproteome as a valuable resource for unraveling the mechanisms employed by trypanosomatid parasites to infect insect hosts by interacting with the gut environment.Graphical

The Genome of Arsenophonus sp. and Its Potential Contribution in the Corn Planthopper, Peregrinus maidis.

The co-evolution between symbionts and their insect hosts has led to intricate functional interdependencies. Advances in DNA-sequencing technologies have not only reduced the cost of sequencing but, with the advent of highly accurate long-read methods, have also enabled facile genome assembly even using mixed genomic input, thereby allowing us to more easily assess the contribution of symbionts to their insect hosts. In this study, genomic data recently generated from Peregrinus maidis was used to assemble the genome of a bacterial symbiont, Pm Arsenophonus sp. This ~4.9-Mb assembly is one of the largest Arsenophonus genomes reported to date. The Benchmarking Universal Single-Copy Orthologs (BUSCO) result indicates that this Pm Arsenophonus assembly has a high degree of completeness, with 96% of the single-copy Enterobacterales orthologs found. The identity of the Pm Arsenophonus sp. was further confirmed by phylogenetic analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicates a major contribution by Pm Arsenophonus sp. to the biosynthesis of B vitamins and essential amino acids in P. maidis, where threonine and lysine production is carried out solely by Pm Arsenophonus sp. This study not only provides deeper insights into the evolutionary relationships between symbionts and their insect hosts, but also adds to our understanding of insect biology, potentially guiding the development of novel pest control methods.

Diversity of insect galls in veredas of the Brazilian Cerrado in Minas Gerais, Brazil

Brazilian veredas are hygrophilous communities with high species diversity, featuring many floristic studies but a still incipient number of faunistic studies. In the present study, we conducted an inventory of insect galls in four different veredas located in the Northern region of Minas Gerais, Brazil. Overall, we found 75 gall morphotypes, distributed across 50 host species representing 37 plant genera and 22 families. Fabaceae was the plant family with the greatest number of insect gall morphotypes (n = 21), followed by Malpighiaceae (n = 10). The plant genera that supported the highest diversity of insect galls were Copaifera (n = 8) and Byrsomima (n = 5). The plant species Copaifera oblongifolia (n = 6) and Anacardium humile (n = 4) exhibited the highest richness of insect galls. The leaves were the most attacked organs (89% of all galls). Most morphotypes are glabrous (83%), green (69%) and lenticular (60%). The taxa of gall-inducing insects were identified for 46 morphotypes (80%), and were recorded inducers from the orders Diptera, Lepidoptera, and Hymenoptera. Cecidomyiidae (Diptera) was the most representative galling group, with 42 morphotypes, making up 93.3% of the recorded inducers. Among the sampled veredas areas, the Vereda do Peruaçu presented the highest richness of insect gall morphotypes and host plant species. The faunistic similarity was higher in the Pedras and Tiririca veredas, followed by Almescla and Peruaçu veredas. This is the first systematic inventory of insect galls and their host plant in Brazilian veredas. The diversity of insect galls in the studied veredas is relatively high when compared to other Brazilian Cerrado vegetation types.

NEW EXTRACTION METHOD OF ENTOMOPATHOGENIC NEMATODES USING THE BASIC FLOTAC AND THE MINI-FLOTAC TECHNIQUES

The FLOTAC basic technique is a recognised method used mainly in the veterinary field to extract parasites from the faeces of animals found in the stomach and intestine. This study is the first application of the FLOTAC and Mini-FLOTAC techniques to extract infective juveniles of entomopathogenic nematodes from infested Galleria mellonella. The EPN used for this purpose was an endemic Italian nematode belonging to the Rhabitidae family Steinernema carpocapsae. Galleria mellonella larvae were infected and extraction was performed a few days after infection using both techniques. A comparison was then made between the two methods. The results showed that infective juveniles could be extracted from the infected larva as early as three days after infection. The difference between the FLOTAC basic technique and the Mini-FLOTAC technique was not significant in the extraction of entomopathogenic nematodes. Due to its sensitivity and operating easiness the Mini-FLOTAC technique is a promising method for the extraction of entomopathogenic nematodes. It allows faster extraction of nematodes from the inhabited soil and insect host than the conventional White trap method. Key Words: Microbial biocontrol, Entomopathogenic nematodes, Nematode extraction, FLOTAC, Mini-FLOTAC

Insect Gut Microbiota and Pesticide Degradation in Response to Innate Metabolites- a Review

Insects host a diverse microbiota in their gut, encompassing bacteria, fungi, viruses, and archaea, influencing their physiology, nutrition, and overall health. The composition of these microbial communities varies with factors like insect species, diet, and the environment. Insect gut microbiota serve pivotal roles such as aiding digestion, synthesizing essential nutrients, safeguarding against pathogens, and detoxifying toxins, including insecticides. A particularly promising facet of their function lies in influencing the metabolism of insecticides. These gut microbiotas can either augment or diminish insecticide toxicity through mechanisms like enzymatic breakdown, sequestration, target site alteration, or modulation of the insect's immune response. Understanding these interactions is paramount for devising sustainable pest management strategies. This review explores into insect gut microbiota, their impact on insecticide susceptibility, and the potential use of microbial metabolites in eco-friendly pest control. We explore pesticide degradation mechanisms, the consequences of microbiota disruption on susceptibility, and the role of microbiota-produced metabolites in shaping pesticide efficacy. Ultimately, we highlight the potential of microbiota manipulation as a strategy to enhance insecticide effectiveness and combat pesticide resistance in pest management.