Specialist Insect Research Articles

High levels of sinigrin trigger synthesis of fatty acids in Plutella xylostella (L.).

Diamondback moth (Lepidoptera: Plutellidae; Plutella xylostella L.) is a specialist insect of the Brassicaceae family, damaging economically important crops, such as cabbage and cauliflower. Glucosinolates, also known as 'mustard oil bombs' are present in all Brassicaceae members, of which sinigrin (allyl-glucosinolate or 2-propenyl-glucosinolate) is a major aliphatic compound. During herbivory, glucosinolates are converted to toxic isothiocyanates that deter insect pests. P. xylostella possesses glucosinolate sulfatases that desulfate them. Such a conversion renders them unfit for degradation to toxic products. Changes in the larval performance prompted us for RNA sequencing to understand probable adaptation mechanism under sinigrin stress. Differentially expressed genes were found to be related to larval cuticle proteins. Further, gene ontology and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses depict genes belonging to the categories, integral component of membrane, cellular processes and those involved in biosynthesis of fatty acids. Upregulation of cuticular genes viz. larval cuticle protein-17 (LCP-17), cuticular protein-19 (2CP-19) and ATP binding cassette transporter C7 (ABCC7), ABCC16 was validated by qRT-PCR. Liquid chromatography quadrupole time of flight mass spectrometry analysis of whole larvae feeding on sinigrin and their separated cuticle, depicted abundance of fatty acids. Changes in the topography of the larval cuticle were evident by scanning electron microscopy. Expression of PxABCH1 was corroborated to its role in the transport of cuticular lipids. Notably, molecular docking of PxABCH1 with cuticular fatty acids showed favorable binding interactions. To summarize, integrated transcriptomic and metabolomic analyses suggest that in response to a diet containing a high dose of sinigrin, P. xylostella re-programs metabolic pathways related to fatty acid biosynthesis that directly influence insect development.

OsMYB1 antagonizes OsSPL14 to mediate rice resistance to brown planthopper and Xanthomonas oryzae pv. oryzae.

OsMYB1 negatively mediates rice resistance to brown planthopper and rice blight. Additionally, OsMYB1 interacts with OsSPL14 and antagonizes its function by oppositely regulating downstream resistance-related genes. In their natural habitats, plants are concurrently attacked by different biotic factors. Xanthomonas oryzae pv. oryzae (Xoo) is a pathogen that severely deteriorates rice yield and quality, and brown planthopper (BPH; Nilaparvata lugens) is a rice specific insect pest with the damage topping other pathogens. Although genes for respective resistance to BPH and Xoo have been widely reported, few studies pay attention to simultaneous resistance to both. In this study, we identified a MYB transcription factor, OsMYB1, which exhibited diverse transcriptional regulatory capabilities and a negative regulatory role in resistance to both BPH and Xoo. Biochemical and genetic analysis proved OsMYB1 to be a TF that could interact with OsSPL14, a positive regulator of rice resistance to Xoo. OsSPL14 mutants showed increased sensitivity to BPH, suggesting that OsSPL14 is contrary to OsMYB1 in regulating rice resistance to these two biotic stresses. Consistently, OsMYB1 and OsSPL14 displayed opposite functions in regulating defense-related genes. OsMYB1 can form transcription regulation complexes with repressor OsJAZs instead of co-repressor TOPLESS to possibly realize its transcriptional repression function. Taken together, we concluded that two interacting TFs in rice, OsMYB1 and OsSPL14, played antagonistic roles in regulating resistance to BPH and Xoo.

Two secretory T2 RNases from a fungal pathogen target distinct insect cell transmembrane proteins to cause cytotoxicity.

Fungal pathogens produce secretory ribonuclease (RNase) T2 proteins during infection, which contribute to fungal virulence via their enzyme functions in degradation of host cell RNA. However, the details of those proteins entering the host cells are unclear. Our previous study demonstrated that the two secretory RNase T2 members, BbRNT2 and BbTrv, produced by the insect fungal pathogen Beauveria bassiana, caused cytotoxic damage to insect cells and contributed to fungal virulence. Here, the Spodoptera frugiperda ovarian epithelial cells (sf9 cells) were used as models to investigate the interactions of the two fungus-produced RNase T2 proteins with the insect cells. Two transmembrane proteins, an ABC transporter (SfABCG) and an Innexin 7-like protein (Sfinx), were identified from the sf9 cells as interacting with BbRNT2 and BbTrv, respectively, through protein immunoprecipitation, yeast-two hybrid tests and protein pull-down assays. Although a slight decrease in the sf9 cell viability was examined by transfection of RNA interference of SfABCG or Sfinx, the transfected cells displayed a dramatically decreased sensitivity to BbRNT2 or BbTrv, suggesting the requirement of the twotransmembrane proteins for BbRNT2 and BbTrv to enter the insect cells. These results reveal a mechanism of the cytotoxic molecules, T2 RNases, produced by the fungal pathogen, entering the insect cells via interaction with specific insect cell transmembrane proteins and causing cytotoxic damage.

Metabolomic Diversity and Defensive Phenolic Compounds in Cloud Forest Ferns.

The few current metabolomic studies on ferns are mostly restricted to a single species or focused on specific compounds. We performed an untargeted metabolomic study on six of the most common fern species from the cloud forest, followed by a targeted analysis of 64 phenolic compounds, many of which have been associated with herbivore defense. The untargeted analysis revealed a total of 232 putatively identified metabolites from 463 to 1427 signals per fern species, each with its proper chemical signature but not necessarily correlated to their phylogenetic relationship. The flavonoid, flavone, and flavonol biosynthesis were the most expressed pathways in all species except for Marattia laxa. Fern species also differed strongly in the concentrations of the 10 detected phenolic compounds. Our results show that ferns, including the most ancestral species, such as M. laxa, display a high metabolomic diversity comparable to seed plants. Each fern species held a different combination of defensive phenolic compounds. Further research is needed to explore the metabolic diversity, to identify the biochemical defenses of ferns, and, in particular, to detect the chemical compounds that act against their specific herbivorous insects in the cloud forest ecosystem.

The 'genetic zipper' method offers a cost-effective solution for aphid control.

Twenty years ago, it was difficult to imagine the use of nucleic acids in plant protection as insecticides, but today it is a reality. New technologies often work inefficiently and are very expensive; however, qualitative changes occur during their development, making them more accessible and work effectively. Invented in 2008, contact oligonucleotide insecticides (olinscides, or DNA insecticides) based on the CUAD (contact unmodified antisense DNA) platform have been substantially improved and rethought. The main paradigm shift was demonstrating that unmodified antisense DNA can act as a contact insecticide. Key breakthroughs included identifying convenient target genes (rRNA genes), mechanism of action (DNA containment), and discovering insect pests (sternorrhynchans) with high susceptibility to olinscides. Today, the CUAD platform possesses impressive characteristics: low carbon footprint, high safety for non-target organisms, rapid biodegradability, and avoidance of target-site resistance. This next-generation class of insecticides creates opportunities for developing products tailored for specific insect pest populations. The 'genetic zipper' method, based on CUAD biotechnology, integrates molecular genetics, bioinformatics, and in vitro nucleic acid synthesis. It serves as a simple and flexible tool for DNA-programmable plant protection using unmodified antisense oligonucleotides targeting pest rRNAs. Aphids, key pests of important agricultural crops, can be effectively controlled by oligonucleotide insecticides at an affordable price, ensuring efficient control with minimal environmental risks. In this article, a low-dose concentration (0.1 ng/µL; 20 mg per hectare in 200 L of water) of the 11 nt long oligonucleotide insecticide Schip-11 shows effectiveness against the aphid Schizolachnus pineti, causing mortality rate of 76.06 ± 7.68 on the 12th day (p<0.05). At a consumption rate of 200 L per hectare, the cost of the required oligonucleotide insecticide is about 0.5 USD/ha using liquid-phase DNA synthesis making them competitive in the market and very affordable for lab investigations. We also show that non-canonical base pairing Golinscide: UrRNA is well tolerated in aphids. Thus, non-canonical base-pairing should be considered not to harm non-target organisms and can be easily solved during the design of oligonucleotide insecticides. The 'genetic zipper' method, based on CUAD biotechnology, helps quickly create a plethora of efficient oligonucleotide pesticides against aphids and other pests. Already today, according to our estimations, the 'genetic zipper' is potentially capable of effectively controlling 10-15% of all insect pests using a simple and flexible algorithm.

FRUIT GROWING NUCLEAR STOCK IN PROGRESS AT RIFG PITEȘTI

Nuclear stocks are in a permanent and dynamic evolution because of new assortments and legislative changes. At the present time, the production and maintenance of nuclear stocks from higher biological categories especially, is carried out based on the requirements of several legislative acts, which provide rules starting from the selection of the material, up to the consumers, material labeled with mention "EU norms and standards". At RIFG Pitesti, are active all three components of such a process: 1. Obtaining mother plants under the requirements of authenticity, quality, traceability, phytosanitary assessment for the free from harmful organisms’ status. The working methods include viral tests by biological, serological ELISA and molecular PCR techniques; 2. Maintaining of the mother plants in special insect proof spaces or in the field; 3. Exploitation of nuclear stock by vegetative multiplication: in vitro cultures and other classic methods. At RIFG Pitești, there are under operation 2 categories of mother plantations: established before 2017 and exploitable until 2029 (according to O.M 40/2023) and mother plantations established after 2017 in accordance with the new legislation. (O.M.784/2016, O.M. 119/2020, O.M. 40/2023).

Cochineal (Dactylopius coccus Costa) Pigment Extraction Assisted by Ultrasound and Microwave Techniques.

Carminic acid is a natural pigment typically found in several insect taxa, including specific insects such as "grana cochinilla fina" in Mexico (Dactylopius coccus Costa). Commercially, it is also referred to as carmine, which is a more concentrated solution presenting as at least 50% carminic acid. To date, this dye has been used in the pharmaceutical, food and cosmetic industries. Unfortunately, one of the main limitations has to do with establishing the appropriate extraction and purification protocol. Currently, there is growing interest in developing eco-friendly and efficient pigment extraction processes for various applications. In this study, we compare the ultrasound- and microwave-assisted extraction versus with a conventional method to obtain carminic acid from cochineal. To do this, we considered three factors that influence the extraction process as independent variables: solvent volume, temperature and irradiation time. The optimization was carried out using the response surface methodology, employing a three-factor and three-level Box-Behnken experimental design. Carminic acid contents were quantified by UV-Vis spectroscopy, and extracts were evaluated by infrared spectroscopy to verify the integrity of the carminic acid molecule. The yield obtained by ultrasound-assisted extraction was 49.2 ± 3.25, with an efficiency of 31.3 mg/min, while microwave-assisted extraction showed a yield of 40.89 ± 2.96, with an efficiency of 27.3 mg/min. Both methods exceeded the extract yield (31.9 ± 3.4%) and efficiency (10.6 mg/min) obtained with the conventional method, demostrating that ultrasound- and microwave-assisted extraction are viable alternatives for obtaining carminic acid, with the potential to be scaled up to an industrial level.

Habitat management interventions for a specialist mid- successional grassland butterfly, the Lulworth Skipper

Evidence-based management is needed to reverse declines in insect abundance. The Lulworth Skipper Thymelicus acteon is a range-restricted and declining species in the UK and northern Europe associated with mid-successional grassland, which presents management challenges because interventions are necessary to prevent long-term habitat deterioration but can result in short-term reductions in quality. In addition, site management should be compatible for the focal species and for wider plant and insect diversity. We conducted factorial experimental management trials to understand effects of cutting and rotovation on the height and structure of vegetation containing the larval host plant Tor-grass Brachypodium rupestre. We monitored vegetation height, B. rupestre cover and plant diversity, and T. acteon larval presence over four years. Rotovation and cutting differed in their effects on habitat structure and larval occupancy relative to controls. Vegetation height and host plant cover, the most important components of habitat quality for T. acteon, were faster to recover to suitable levels on cut plots. However, larval occupancy increased more quickly on rotovated plots, where plant species diversity was also higher. Results suggest that due to initial negative impacts of interventions on T. acteon occupancy, low frequency or low-intensity management, such as managing sections of a site every three years, is advisable. Our results show that rotovation or cutting the sward can be suitable for mid-successional grassland species such as Lulworth Skipper on sites where grazing might be problematic. Rotational grazing or rotovation can maintain suitable conditions for habitat specialist insects requiring a range of different grassland conditions, serving wider conservation goals.

Population genomics of a specialized insect, Tetraopes texanus (Coleoptera: Cerambycidae), across a fragmented grassland system

AbstractSpecialist insects are especially susceptible to loss of genetic diversity in the face of habitat destruction and fragmentation. Implementing effective conservation practices for specialist insects will benefit from knowledge of population structure and genetic diversity. Because insects are hyper-diverse, characterizing the population structure of all species within the insect community is untenable, even if focused within a particular habitat type. Thus, concentrating on a single species specialized to a particular habitat type is needed to infer general trends. Here, we investigate the range-wide population genetics of Tetraopes texanus Horn 1878 (Coleoptera: Cerambycidae), which provides a useful model of grassland insects due to its’ habitat specificity and unique biology. Tetraopes texanus occurs primarily in Texas and Oklahoma, into Northern Mexico, and possibly into eastern New Mexico but also occurs in Black Belt prairies of Mississippi and Alabama. Mitochondrial and nuclear DNA (RAD-seq) analysis identified two distinct population clusters of T. texanus corresponding to the Texas and Oklahoma population and the Mississippi and Alabama population. Demographic models indicate ongoing, though incomplete, isolation of the two populations, with estimated dates of divergence in the mid-Pleistocene, coinciding with the end of a glacial period and a shift in glacial interval. These results can inform conservation of grassland adapted insects and offers insight to the biogeography of the Gulf Coastal Plain.

Insects decline with host plants but coextinctions may be limited

The loss of wild plant populations is often assumed to lead to coextinctions, particularly among specialized insects. Despite global declines in both terrestrial insects and plants, the relationship between these trends remains elusive. Here, we address this gap by analyzing the relationship between population trends of insects and their host plants in Germany, encompassing over 150,000 interactions among 3,429 plant and 2,239 insect species, including both pollinators (bees and hoverflies) and herbivores (butterflies, moths, and sawflies). Our findings reveal parallel population declines of insects and host plants across taxa, except for more generalist hoverflies. However, simulated extinctions of threatened host plants led to limited coextinctions in insects. Notably, 96% of insect species retained over 25% of their host plant diversity, and among those, 98% still retained at least one common species in their interaction portfolio. Even highly specialized insects may persist because they tend to specialize in nonthreatened plant species. While uncertainties remain regarding the interchangeability of host plants, our findings suggest that insect coextinctions are far from a 1:1 match with plant extinctions. Our findings suggest the declining abundance of many plant species can contribute to insect decline yet challenge the common assumption that the extinction of threatened plant species will necessarily trigger an imminent extinction wave of associated insects. Interaction networks seem to be more resilient.

Global proliferation of nonnative plants is a major driver of insect invasions.

Invasions by nonnative insect species can massively disrupt ecological processes, often leading to serious economic impacts. Previous work has identified propagule pressure as important driver of the trend of increasing numbers of insect invasions worldwide. In the present article, we propose an alternative hypothesis-that insect invasions are being driven by the proliferation of nonnative plants, which create niches for insect specialists and facilitate their establishment outside their native ranges where their hosts are planted or are invasive. We synthesize mechanisms by which plant invasions facilitate insect invasions, macroecological patterns supporting the tight link between plant and insect invasions, and case studies of plant invasions having facilitated subsequent insect establishment. This body of evidence indicates that plant invasions are a major driver of insect invasions. Consequently, the benefits of limiting the spread of nonnative plants include averting the proliferation of nonnative insects and their spillover onto native plant species.

Virome Characterization of Native Wild-Rice Plants Discovers a Novel Pathogenic Rice Polerovirus With World-Wide Circulation.

Pandemics originating from zoonotic viruses have posed significant threats to human health and agriculture. Recent discoveries have revealed that wild-rice plants also harbour viral pathogens capable of severely impacting rice production, a cornerstone food crop. In this study, we conducted virome analysis on ~1000 wild-rice individual colonies and discovered a novel single-strand positive-sense RNA virus prevalent in these plants. Through comprehensive genomic characterization and comparative sequence analysis, this virus was classified as a new species in the genus Polerovirus, designated Rice less tiller virus (RLTV). Our investigations elucidated that RLTV could be transmitted from wild rice to cultivated rice via a specific insect vector, the aphid Rhopalosiphum padi, causing less tiller disease symptoms in rice plants. We generated an infectious cDNA clone for RLTV and demonstrated systemic infection of rice cultivars and induction of severe disease symptoms following mechanical inoculation or stable genetic transformation. We further illustrated transmission of RLTV from stable transgenic lines to healthy rice plants by the aphid vector, leading to the development of disease symptoms. Notably, our database searches showed that RLTV and another polerovirus isolated from a wild plant species are widely circulating not only in wild rice but also cultivated rice around the world. Our findings provide strong evidence for a wild plant origin for rice viruses and underscore the imminent threat posed by aphid-transmitted rice Polerovirus to rice cultivar.

A Host Tree and Its Specialist Insects: Black Locust (Robinia pseudoacacia) Availability Largely Determines the Future Range Dynamics of Its Specialist Insects in Europe.

Black locust is the only host of Robinia-specialist insects in Europe. However, no study to date has examined future range shifts of specialist insects, and the relative effects of host plant availability and other factors on their range shifts. Here, we characterized the future range shifts in the host and its four specialist insects and the factors contributing to changes in their ranges. We detected substantial range expansions in all target species. Climate predictors and host plant availability were expected to have the strongest effects on the range shifts in the host and its specialist insects, respectively, suggesting that the specialist insects will track the ranges of their host. Parectopa robiniella showed the largest potential and expanding ranges and should be made a priority species for controlling invasions of Robinia-specialist insects in Europe. The expanding ranges of all specialist species were largely identified in the United Kingdom, Germany, and France, suggesting that these should be priority regions for mitigating their effects on ecosystems. Reducing future climate change is essential for preventing the spreading of specialist insects in Europe since specialist insects track their specialist host plants, and host range expansions are mainly driven by future climate changes.

Citrus Fruits Produce Direct Defense Responses against Oviposition by Bactrocera minax (Diptera: Tephritidae).

Plants perceive and orchestrate defense responses when herbivorous insects are ovipositing. Fruits, as a crucial reproductive organ in plants, have rarely been researched on the responses to insect eggs. Here, we found that oviposition by the specialist insect Bactrocera minax in navel oranges activated the lignin synthesis pathway and cell division, causing mechanical pressure that crushed the eggs. Transcriptome and metabolome analyses revealed an enrichment of oviposition-induced genes and metabolites within the lignin synthesis pathway, which was confirmed by histochemical staining. Furthermore, hydrogen peroxide (H2O2) accumulation was observed at the oviposition sites. Plant defense-related hormones jasmonic acid (JA) and salicylic acid (SA) exhibited rapid induction after oviposition, while indole-3-acetic acid (IAA) activation occurred in the later stages of oviposition. Additionally, secondary metabolites induced by prior egg deposition were found to influence larval performance. Our studies provide molecular evidence that host fruits have evolved defense mechanisms against insect eggs and pave the way for future development of insect-resistant citrus varieties.

Studies on Relative Abundance and Diversity of Insect Fauna in Cotton in Rajendranagar, Telangana, India

The accurate documentation of insects is crucial for studying biodiversity and population dynamics. Given the resilience of the majority of insect species, proper sampling necessitates the utilization of suitable strategies for capturing specific insects. However, the diversity and types of insect species present in major crops cultivated in Rajendranagar remain poorly understood. Consequently, a comprehensive investigation of the diversity of different insect species in cotton crop was conducted during the period from September 2021 to February 2022 at College Farm. A total of 10,233 individuals from 47 families and 10 orders were documented. Among the orders, Hemiptera recorded the highest number of 4,256 individuals followed by Coleoptera (2,567), while the minimum number of individuals was observed in the order Neuroptera (12). Notably, the order Hemiptera exhibited the highest Shannon-Weiner index value (H = 1.78) and species richness (R = 0.963). However, evenness was found to be highest in Orthoptera (e = 0.826). Furthermore, the order Hemiptera displayed the highest relative abundance (RA) with a value of 41.59%, whereas Neuroptera exhibited the lowest relative abundance with a value of 0.12%.

Baculoviruses in Integrated Pest Management of Fall Armyworm, (Spodoptera frugiperda) (Lepidoptera: Noctuidae): Structure, Classification and Application

Baculoviruses are crucial biological agents in integrated pest management (IPM), particularly for controlling lepidopteran pests in agriculture. These are highly specific, eco-friendly viruses characterized by rod-shaped nucleocapsids containing a protein-encased genome. The Baculoviridae family comprises four genera: Alphabaculovirus, Betabaculovirus, Gammabaculovirus, and Deltabaculovirus, each targeting specific insect orders. Nucleo polyhedron virus (NPVs) and granuloviruses (GVs) are extensively used in pest management due to their high virulence and specificity, ensuring safety for non-target organisms. Ascoviruses are dsDNA viruses that infect Spodoptera frugiperda larvae, transmitted primarily by parasitoids. Despite high virulence, their use in pest control is limited due to ineffective oral transmission. Combining ascoviruses with other pathogens, such as Bacillus thuringiensis kurstaki (Btk), may enhance their pest control potential. The infection process begins when insect larvae ingest viral occlusion bodies, leading to systemic infection and host death. Despite their narrow host range and slower action compared to chemical insecticides, baculoviruses are invaluable in sustainable agriculture. Their application has expanded beyond pest control to include gene therapy and vaccine production. This review examines the structure, classification, infection process, and current status of baculoviruses in controlling the fall armyworm, Spodoptera frugiperda, a significant agricultural pest. By exploring their potential as a cornerstone in biological pest management, we highlight the importance of baculoviruses in developing sustainable and environmentally friendly pest control strategies. The integration of baculoviruses into IPM programs offers a promising approach to reduce chemical pesticide use, preserve biodiversity, and enhance crop protection, ultimately contributing to more sustainable agricultural practices and food security.

Eco-evolutionary factors contribute to chemodiversity in aboveground and belowground cucurbit herbivore-induced plant volatiles.

When attacked by insect herbivores, plants emit blends of chemical compounds known as herbivore-induced plant volatiles (HIPVs). Although HIPVs are produced both aboveground and belowground, how HIPVs vary across plant tissues remains unresolved, as do the selective forces shaping interspecific HIPV emission patterns. Here, we compared foliar and root HIPVs within and among closely related plant species and evaluated if different eco-evolutionary forces, including plant domestication, coexistence histories with herbivores, or phylogenetic relatedness, explain HIPV blends. To examine aboveground and belowground patterns in HIPVs, we compared leaf and root volatile profiles for six species in the Cucurbitaceae that differed in domestication status and coexistence history with specialist insect herbivores. We predicted that within-species HIPVs from different tissues would be more similar than HIPV blends among different species, and that plant volatile chemodiversity was reduced by domestication and enhanced by coexistence histories with herbivores. We found that herbivory induced both quantitative and qualitative changes in volatile emissions across all plant species, which were more pronounced aboveground than belowground. Each species produced tissue-specific HIPVs, and foliar and root HIPVs differed among species. Contrary to our predictions, plant domestication enhanced foliar volatile diversity, while coexistence histories with herbivores reduced foliar and root volatile diversity. Additionally, phylogenetic relatedness did not correlate with aboveground or belowground volatiles. Overall, this work furthers our understanding of the eco-evolutionary forces driving patterns in aboveground and belowground HIPV emissions, elucidating an important and previously undescribed component of within-plant variation in chemodiversity.

Exploring the potential of insect gut symbionts for polyethylene biodegradation

The global issue of synthetic plastic pollution is escalating, necessitating innovative bioremediation approaches. Specific insect species have developed symbiotic associations with intestinal microorganisms that possess the ability to degrade resistant plant materials, such as lignocellulose. This is the first study to our knowledge to isolate, characterize, and compare microbial isolates (yeast and bacteria) extracted from the guts of wood-feeding termites (WFT) and lesser waxworms (LWW). The objective was to determine their efficacy in decomposing recalcitrant pollutants, such as low-density polyethylene (LDPE). The isolates belonged to numerous taxonomic groups, as determined by molecular identification; these groups included Bacillus, Citrobacter, Cellulosimicrobium, Rhodococcus, Pseudomonas, Candida, and others. A number of isolates had the potential to degrade LDPE. After 45 days of incubation, the polymer sheets lost 19.8 % of their weight for Bacillus cereus (LDPE-DB2) and 15.4 % of their weight for Candida guilliermondii (LDPE-DY6). Additionally, LDPE degraded by LDPE-DY6 showed a tensile strength loss of 50.3 % compared to that degraded by LDPE-DB2 (58.3 %). During this time, robust biofilm formation was observed on the surfaces of the polymers. Extracellular enzymes such as cutinases, aryl alcohol oxidases, and peroxidases, secreted by specific yeast and bacterial isolates, contribute to the degradation of plastic and recalcitrant biopolymers. Notably, the isolates from LWW demonstrated a greater advantage in this regard than those from WFT. Bacillus cereus, Pseudomonas aeruginosa, Candida guilliermondii, and Sterigmatomyces halophilus were found to have the highest activities in degrading LDPE among the studied WFT and LWW gut-derived symbionts. This study paves the way for a new opportunity to enhance polyethylene degradation by insect gut bacteria and yeasts that may facilitate biotechnological applications for plastic waste remediation.

Spatial differentiation characteristics of the Hemiptera insects in China.

The Hemiptera insects are the largest incomplete metamorphosis insect group in Insecta and play a vital role in ecosystems and biodiversity. Previous studies on the spatial distribution of Hemiptera insects mainly focused on a specific region and insect, this study explored the spatial distribution characteristics of Hemiptera insects in China (national scale), and further clarified the dominant factors affecting their spatial distribution. We used spatial autocorrelation analysis, hot spot analysis, and standard ellipse to investigate the spatial distribution characteristics of Hemiptera insects in China. Furthermore, we used geographic detectors to identify the main factors affecting their spatial distribution under China's six agricultural natural divisions and explore the influencing mechanism of dominant factors. The results show that: (i) The spatial differentiation characteristics of Hemiptera insects in China are significant, and their distribution has obvious spatial agglomeration. The Hu Huanyong Line is an important dividing line for the spatial distribution of Hemiptera insects in China. From the city scale, the HH type (high-high cluster) is mainly distributed on both sides of the Hu Huanyong Line. (ii) The hot spots of Hemiptera insects are mainly distributed in southwest China, along the Qinling Mountains, the western side of the Wuyi Mountains, the Yinshan Mountains, the Liupanshan Mountains, the Xuefeng Mountains, the Nanling Mountains, and other mountainous areas. (iii) Under agricultural natural divisions, the influence of natural environmental factors on the spatial distribution of Hemiptera insects is obviously different. Temperature and precipitation are the dominant factors. Natural factors and socio-economic factors have formed a positive reinforcement interaction mode on the spatial distribution of Hemiptera insects. These can provide the decision-making basis for biodiversity conservation and efficient pest control.

Host range of naturally and artificially evolved symbiotic bacteria for a specific host insect.

Diverse insects are intimately associated with specific symbiotic bacteria, where host and symbiont are integrated into an almost inseparable biological entity. These symbiotic bacteria usually exhibit host specificity, uncultivability, reduced genome size, and other peculiar traits relevant to their symbiotic lifestyle. How host-symbiont specificity is established at the very beginning of symbiosis is of interest but poorly understood. To gain insight into the evolutionary issue, we adopted an experimental approach using the recently developed evolutionary model of symbiosis between the stinkbug Plautia stali and Escherichia coli. Based on the laboratory evolution of P. stali-E. coli mutualism, we selected ΔcyaA mutant of E. coli as an artificial symbiont of P. stali that has established mutualism by a single mutation. In addition, we selected a natural cultivable symbiont of P. stali of relatively recent evolutionary origin. These artificial and natural symbiotic bacteria of P. stali were experimentally inoculated to symbiont-deprived newborn nymphs of diverse stinkbug species. Strikingly, the mutualistic E. coli was unable to establish infection and support growth and survival of all the stinkbug species except for P. stali, uncovering that host specificity can be established at a very early stage of symbiotic evolution. Meanwhile, the natural symbiont was able to establish infection and support growth and survival of several stinkbug species in addition to P. stali, unveiling that a broader host range of the symbiont has evolved in nature. Based on these findings, we discuss what factors are relevant to the establishment of host specificity in the evolution of symbiosis.IMPORTANCEHow does host-symbiont specificity emerge at the very beginning of symbiosis? This question is difficult to address because it is generally difficult to directly observe the onset of symbiosis. However, recent development of experimental evolutionary approaches to symbiosis has brought about a breakthrough. Here we tackled this evolutionary issue using a symbiotic Escherichia coli created in laboratory and a natural Pantoea symbiont, which are both mutualistic to the stinkbug Plautia stali. We experimentally replaced essential symbiotic bacteria of diverse stinkbugs with the artificial and natural symbionts of P. stali and evaluated whether the symbiotic bacteria, which evolved for a specific host, can establish infection and support the growth and survival of heterospecific hosts. Strikingly, the artificial symbiont showed strict host specificity to P. stali, whereas the natural symbiont was capable of symbiosis with diverse stinkbugs, which provide insight into how host-symbiont specificity can be established at early evolutionary stages of symbiosis.