Specialist Insect Research Articles

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

Abstract 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.

Low seed viability of a rare aster

The reproductive ecology of rare plants is often unknown, yet the persistence of most plant populations depends on successful interactions with pollinators and favourable environmental conditions. Sexual reproduction maintains genetic diversity within plant populations using pollinators to transport pollen grains among plants of the same species and producing seeds. We investigated the reproduction of Yermo xanthocephalus Dorn (Desert yellowhead), a perennial member of Asteraceae endemic to central Wyoming, USA, which grows in only two locations within 8 km of each other. Our objectives were to assess the pollination and seed-set of Y. xanthocephalus. We conducted seed-set experiments in both populations to measure self-pollination and estimate if pollinating insects limited seed production. We used vane traps and pan traps to capture pollinators, and we examined pollen carried on bees. Yermo xanthocephalus can self-pollinate, but seed-set was extremely low. The number of viable seeds produced in flowerheads pollinated by insects did not differ from those produced by capitula hand-pollinated with excess pollen, indicating that pollinators did not limit seed production that year. Pollen from Y. xanthocephalus was carried by nine bee genera, suggesting that no one specific insect pollinates this plant. Only 12% of ovules produced viable seeds in the main population and 0% were viable in the other population, suggesting that something beyond pollinators limited seed-set. We recommend continued research to address what is limiting seed production to advance the knowledge and management of this declining plant species.

The Diversity of pollinator insects in vegetable gardens, Kabawo District, Muna Regency

Pollinator insects play an important role in pollination to increase the productivity of flowering plants. The aim of this study was to analyze the abundance, diversity, and specific taxon of insect pollinators among different vegetable crops in local farmers' gardens. Insects were sampled from four gardens, namely polyculture long bean (KKP), eggplant polyculture (KT), curly chili monoculture (KCK), and Indofood chili monoculture (KCI) used nets and light traps. The results showed that the abundance and diversity of pollinator insects varied between gardens. The pollinator insect community in KCI was most similar to that in KCK; KT was similar to the KCI and KCK groups, while KKP were separate from the KT, KCK and KCI groups. The richest genus occurs in KKP, while chili plantations are the poorest. The apis genus in KKP and KT, and the Nomina genus in KCK and KCI were dominant. The specific pollinator insect genus in KKP is the richest. It concluded that plant species and cropping patterns contribute to the composition and diversity of the pollinator insect community.

UDP-glycosyltransferases act as key determinants of host plant range in generalist and specialist Spodoptera species

Phytophagous insects have evolved sophisticated detoxification systems to overcome the antiherbivore chemical defenses produced by many plants. However, how these biotransformation systems differ in generalist and specialist insect species and their role in determining insect host plant range remains an open question. Here, we show that UDP-glucosyltransferases (UGTs) play a key role in determining the host range of insect species within the Spodoptera genus. Comparative genomic analyses of Spodoptera species that differ in host plant breadth identified a relatively conserved number of UGT genes in generalist species but high levels of UGT gene pseudogenization in the specialist Spodoptera picta. CRISPR-Cas9 knockouts of the three main UGT gene clusters of Spodoptera frugiperda revealed that UGT33 genes play an important role in allowing this species to utilize the poaceous plants maize, wheat, and rice, while UGT40 genes facilitate utilization of cotton. Further functional analyses in vivo and in vitro identified the UGT SfUGT33F32 as the key mechanism that allows generalist S. frugiperda to detoxify the benzoxazinoid DIMBOA (2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one), a potent insecticidal phytotoxin produced by poaceous plants. However, while this detoxification capacity is conserved in several generalist Spodoptera species, Spodoptera picta, which specializes on Crinum plants, is unable to detoxify DIMBOA due to a nonfunctionalizing mutation in SpUGT33F34. Collectively, these findings provide insight into the role of insect UGTs in host plant adaptation, the mechanistic basis of evolutionary transitions between generalism and specialism and offer molecular targets for controlling a group of notorious insect pests.

Geographic distribution of terpenoid chemotypes in Tanacetum vulgare mediates tansy aphid occurrence but not abundance

Intraspecific variation of specialized metabolites in plants, such as terpenoids, are used to determine chemotypes. Tansy Tanacetum vulgare exhibits diverse terpenoid profiles that affect insect communities. However, it is not fully known whether patterns of their chemical composition and associated insects vary beyond the community scale. Here, we investigated the geographic distribution of mono‐ and sesquiterpenoid chemotypes in tansy leaves and their relationships with specific insect communities across Germany. We sampled tansy leaves from ten plants with and five plants without aphids in each of 26 sites along a north–south and west–east transect in Germany. Hexane‐extracted metabolites from leaf tissues were analyzed by gas chromatography‐mass spectrometry (GC‐MS). Plant morphological traits, aphid occurrence and abundance, and occurrence of ants were recorded locally. The effect of plant chemotype, plant morphological parameters, and abiotic site parameters such as soil types, temperature and precipitation on insect occurrences were analyzed. Plants clustered into four monoterpenoid and four sesquiterpenoid chemotype classes. Monoterpene classes differed in their latitudinal distribution, whereas sesquiterpenes were more evenly distributed across the transect. Aphid and ant occurrence was influenced by monoterpenoids. Plants of monoterpenoid class 1 were colonized by aphids and ants significantly more often than expected by chance, whereas in other classes there were no significant differences. Aphid abundance was affected by soil type, and average annual temperature positively correlated with the occurrence of ants. We found significant geographic patterns in the distribution of tansy chemodiversity and show that monoterpenoids affect aphid and ant occurrence, while the soil type can influence aphid abundance. We show that geographic variation in plant chemistry influences insect community assembly on tansy plants.

Gut microbiota metagenomics and mediation of phenol degradation in Bactrocera minax (Diptera, Tephritidae).

Gut microbiota mediating insect-plant interactions have many manifestations, either by provisioning missing nutrients, or by overcoming plant defensive reactions. However, the mechanism by which gut microbiota empower insects to survive by overcoming a variety of plant secondary metabolites remains largely unknown. Bactrocera minax larvae develop in immature citrus fruits, which present numerous phenolic compounds that challenge the larvae. To explore the role of gut microbes in host use and adaptability, we uncovered the mechanisms of phenol degradation by gut microbes using metagenomic and metatranscriptomic analyses, and verified the degradation ability of isolated and cultured bacteria. Research on this subject can help develop potential strain for the environmental friendly pest management operations. We demonstrated the ability of gut microbes in B. minax larvae to degrade phenols in unripe citrus. After antibiotic treatment, coniferyl alcohol and coumaric aldehyde significantly reduced the survival rate, body length and body weight of the larvae. The metagenomic and metatranscriptomic analyses in B. minax provided evidence for the presence of genes in bacteria and the related pathway involved in phenol degradation. Among them, Enterococcus faecalis and Serratia marcescens, isolated from the gut of B. minax larvae, played critical roles in phenol degradation. Furthermore, supplementation of E. faecalis and S. marcescens in artificial diets containing coniferyl alcohol and coumaric aldehyde increased the survival rate of larvae. In summary, our results provided the first comprehensive analysis of gut bacterial communities by high-throughput sequencing and elucidated the role of bacteria in phenol degradation in B. minax, which shed light on the mechanism underlying specialist insect adaption to host secondary metabolites via gut bacteria. © 2024 Society of Chemical Industry.

Understanding consumers attitude towards insects as food: Influence of insect species on liking, emotions, sensory perception and food pairing

Entomophagy studies mainly focused on insects as a generic category, rarely considering insect species. This study investigated the: i) affective response to specific edible insect species; ii) sensory properties characterizing the tested insects and their role in driving preferences and food paring. A sensory test (85 consumers, 56.5 % female, 19–73 years) was performed on seven dried whole edible insects at the adult (weaver ants, crickets, grasshoppers), larva (bamboo worms, morio worms, sago worms) and pupae stage (silkworms). For each species, consumers expressed their liking and, through three check-all-that-apply tests, described the perceived sensory properties, the perceived emotions, and their potential food pairings. Results showed a significant effect of the species on all variables. Bamboo worms, weaver ants and grasshoppers resulted the most accepted, followed by morio worms, crickets, and silkworms, while the sago worms were the most disliked. Numerous sensory attributes significantly discriminated among insect species and the drivers of liking and sensory attributes associated to the food pairings were identified. However, two clusters with different preferences and drivers of liking were observed. Moreover, a gender effect was found: i) males associated insects with emotions like calm and wild, while females with glad and pleased; ii) males and females would pair different foods with the insect species. In conclusion, this study provided new knowledge useful for researchers and food industry to develop future insect-based foods and dishes able to meet the expectations of different consumers segments.

GC-MS-based Metabolomics Unravels Metabolites across Larval Development and Diapause of a Specialist Insect.

Plant-insect interactions are a driving force into ecosystem evolution and community dynamics. Many insect herbivores enter diapause, a developmental arrest stage in anticipation of adverse conditions, to survive and thrive through seasonal changes. Herein, we investigated the roles of medium- to non-polar metabolites during larval development and diapause in a specialist insect herbivore, Chlosyne lacinia, reared on Aldama robusta leaves. Varying metabolites were determined using gas chromatography-mass spectrometry (GC-MS)-based metabolomics. Sesquiterpenes and steroids were the main metabolites putatively identified in A. robusta leaves, whereas C. lacinia caterpillars were characterized by triterpenes, steroids, fatty acids, and long-chain alkanes. We found out that C. lacinia caterpillars biosynthesized most of the identified steroids and fatty acids from plant-derived ingested metabolites, as well as all triterpenes and long-chain alkanes. Steroids, fatty acids, and long-chain alkanes were detected across all C. lacinia instars and in diapausing caterpillars. Sesquiterpenes and triterpenes were also detected across larval development, yet they were not detected in diapausing caterpillars, which suggested that these metabolites were converted to other molecules prior to the diapause stage. Our findings shed light on the chemical content variation across C. lacinia development and diapause, providing insights into the roles of metabolites in plant-insect interactions.

Post-ingestive stability of a mulberry Kunitz-type protease inhibitor MnKTI-1 in the digestive lumen of silkworm: dual inhibition towards α-amylase and serine protease.

Adaptation of specialist insects to their host plants and defense responses of plants to phytophagous insects have been extensively recognized while the dynamic interaction between these two events has been largely underestimated. Here, we provide evidence for characterization of an unrevealed dynamic interaction mode of digestive enzymes of specialist insect silkworm and inhibitor of its host plant mulberry tree. MnKTI-1, a mulberry Kunitz-type protease inhibitor, whose messenger RNA (mRNA) transcription and protein expression in mulberry leaf were severely triggered and up-regulated by tens of times in a matter of hours in response to silkworm, Bombyx mori, and other mulberry pest insects, suggesting a quick response and broad spectrum to insect herbivory. MnKTI-1 proteins were detected in gut content and frass of specialist B. mori, and exhibited significant post-ingestive stability. Recombinant refolded MnKTI-1 (rMnKTI-1) displayed binding affinity to digestive enzymes and a dual inhibitory activity to α-amylase BmAmy and serine protease BmSP2956 in digestive juice of silkworm. Moreover, data from in vitro assays proved that the inhibition of recombinant rMnKTI-1 to BmAmy can be reverted by pre-incubation with BmSP15920, an inactivated silkworm digestive protease that lack of complete catalytic triad. These findings demonstrate that mulberry MnKTI-1 has the potential to inhibit the digestive enzyme activities of its specialist insect herbivore silkworm, whereas this insect may employ inactivated proteases to block protease inhibitors to accomplish food digestion. The current work provides an insight to better understand the interacting mode between host plant Kunitz protease inhibitors and herbivorous insect digestive enzymes. © 2024 Society of Chemical Industry.