Chromosome-level genome assembly of the Asian citrus psyllid,Diaphorina citri

Diaphorina citri is a global citrus pest.As a vector insect,it can transmit the causative agents of citrus huanglongbing,causing irreversible losses to the citrus industry.The acquisition of genomic information can provide a molecular genetic basis for effective control of D.citri.Here,the DNBSEQ™,Oxford Nanopore Technologies,and Hi-C technologies are applied to generate a high-quality chromosome-level genome of D.citri.The genome size of D.citri was 523.78 Mb with a scaffold N50 of 47.05 Mb distributed on 13 chromosomes.A total of 250.64 Mb(47.85%)repeat sequences and 24048 protein-coding genes were predicted.Genome resequencing of female and male individuals indicated that the sex chromosome system of D.citri is XO.Phylogenetic analysis demonstrated that D.citri and Pachypsylla venusta,which separated from their most recent common ancestor about 336.62 million years ago,were the most closely related.Additionally,we identified genes potentially involved in detoxification metabolism,pathogen transmission,and honeydew secretion for further investigation.The high-quality genome provides an important reference for developing effective management strategies of D.citri.

Identification and functional characterization of female antennae-biased odorant receptor 23 involved in acetophenone detection of the Indian meal moth Plodia interpunctella

The Indian meal moth,Plodia interpunctella(Lepidoptera:Pyralidae),a globally distributed storage pest,relies on odors that are emitted from stored foods to select a suitable substrate for oviposition.However,the molecular mechanism underlying the chemical communication between P.interpunctella and its host remains elusive.In this study,130 chemosensory genes were identified from the transcriptomes of 7 P.interpunctella tissues,and the quantitative expression levels of all 56 P.interpunctella odorant receptor genes(PintORs)were validated using real-time quantitative polymerase chain reaction.The functional characteristics of 5 PintORs with female antennae-biased expression were investigated using 2-electrode voltage clamp recordings in Xenopus laevis oocytes.PintOR23 was found to be specifically tuned to acetophenone.Acetophenone could elicit a significant electrophysiological response and only attracted mated females when compared with males and virgin females.In addition,molecular docking predicted that the hydrogen bonding sites,TRP-335 and ALA-167,might play key roles in the binding of PintOR23 to acetophenone.Our study provides valuable insights into the olfactory mechanism of oviposition substrate detection and localization in P.interpunctella and points toward the possibility of developing eco-friendly odorant agents to control pests of stored products.

The endogenous antioxidant ability of royal jelly in Drosophila is independent of Keap1/Nrf2 by activating oxidoreductase activity

Royal jelly(RJ)is a biologically active substance secreted by the hypopharyngeal and mandibular glands of worker honeybees.It is widely claimed that RJ reduces oxidative stress.However,the antioxidant activity of RJ has mostly been determined by in vitro chemical detection methods or by external administration drugs that cause oxidative stress.Whether RJ can clear the endogenous production of reactive oxygen species(ROS)in cells remains largely unknown.Here,we systematically investigated the antioxidant properties of RJ using several endogenous oxidative stress models of Drosophila.We found that RJ enhanced sleep quality of aging Drosophila,which is decreased due to an increase of oxidative damage with age.RJ supplementation improved survival and suppressed ROS levels in gut cells of flies upon exposure to hydrogen peroxide or to the neurotoxic agent paraquat.Moreover,RJ supplementation moderated levels of ROS in endogenous gut cells and extended lifespan after exposure of flies to heat stress.Sleep deprivation leads to accumulation of ROS in the gut cells,and RJ attenuated the consequences of oxidative stress caused by sleep loss and prolonged lifespan.Mechanistically,RJ prevented cell oxidative damage caused by heat stress or sleep deprivation,with the antioxidant activity in vivo independent of Keap1/Nrf2 signaling.RJ supplementation activated oxidoreductase activity in the guts of flies,suggesting its ability to inhibit endogenous oxidative stress and maintain health,possibly in humans.

The olfactory system of Pieris brassicae caterpllars:from receptors to glomeruli

Tolfactory system of adult lepidopterans is among the best described neuronal circuits.However,comparatively little is known about the organization of the olfactory system in the larval stage of these insects.Here,we explore the expression of olfactory receptors and the organization of olfactory sensory neurons in caterpillars of Pieris brassicae,a significant pest species in Europe and a well-studied species for its chemical ecology.To describe the larval olfactory system in this species,we first analyzed the head transcriptome of third-instar larvae(L3)and identified 16 odorant receptors(ORs)including the OR coreceptor(Orco),13 ionotropic receptors(IRs),and 8 gustatory receptors(GRs).We then quantified the expression of these 16 ORs in different life stages,using qPCR,and found that the majority of ORs had significantly higher expression in the L4 stage than in the L3 and L5 stages,indicating that the larval olfactory system is not static throughout caterpillar development.Using an Orco-specific antibody,we identified all olfactory receptor neurons(ORNs)expressing the Orco protein in L3,L4,and L5 caterpillars and found a total of 34 Orco-positive ORNs,distributed among three sensilla on the antenna.The number of Orco-positive ORNs did not differ among the three larval instars.Finally,we used retrograde axon tracing of the antennal nerve and identified a mean of 15 glomeruli in the larval antennal center(LAC),suggesting that the caterpillar olfactory system follows a similar design as the adult olfactory system,although with a lower numerical redundancy.Taken together,our results provide a detailed analysis of the larval olfactory neurons in P brassicae,highlighting both the differences as well as the commonalities with the adult olfactory system.These findings contribute to a better understanding of the development of the olfactory system in insects and its life-stage-specific adaptations.

Odorant-binding protein 19 in Monochamus alternatus involved in the recognition of a volatile strongly emitted from ovipositing host pines

Monochamus alternatus is the primary carrier of pine wood nematodes,which pose a serious threat to Pinus spp.in many countries.Newly emerging M.alternatus adults feed on heathy host pines,while matured adults transfer to stressed host pines for mating and oviposition.Several odorant-binding proteins(OBPs)of M.alternatus have been proved to aid in the complex process of host location.To clarify the corresponding relations between OBPs and pine volatiles,more OBPs need to be studied.In this research,MaltOBP19 showed a specific expression in the antennae and mouthparts of M.alternatus,and it was marked in 4 types of antenna sensilla by immunolocalization.Fluorescence binding assays demonstrated the high binding affinity of MaltOBP19 with camphene and myrcene in vitro.In Y-tube olfactory experiments,M.alternatus adults were attracted by camphene and RNAi of OBP19 via microinjection significantly decreased their attraction index.Myrcene induced phobotaxis,but RNAi had no significant effect on this behavior.Further,we found that ingesting dsOBP19 produced by a bacteria-expressed system with a newly constructed vector could lead to the knockdown of MaltOBP19.These results suggest that MaltOBP19 may play a role in the process of host conversion via the recognition of camphene,which has been identified to be strongly released in stressed host pines.In addition,it is proved that knockdown of OBP can be achieved by oral administration of bacteria-expressed double-stranded RNA in M.alternatus adults,providing a new perspective in the control of M.alternatus.

Complex interactions among insect viruses-insect vector-arboviruses

Insects are the host or vector of diverse viruses including those that infect vertebrates,plants,and fungi.Insect viruses reside inside their insect hosts and are vertically transmitted from parent to offspring.The insect virus-host relationship is intricate,as these viruses can impact various aspects of insect biology,such as development,reproduction,sex ratios,and immunity.Arthropod-borne viruses(arboviruses)that cause substantial global health or agricultural problems can also be vertically transmitted to insect vector progeny.Multiple infections with insect viruses and arboviruses are common in nature.Such coinfections involve complex interactions,including synergism,dependence,and antagonism.Recent studies have shed light on the influence of insect viruses on the competence of insect vectors for arboviruses.In this review,we focus on the biological effects of insect viruses on the transmission of arboviruses by insects.We also discuss the potential mechanisms by which insect viruses affect the ability of hosts to transmit arboviruses,as well as potential strategies for disease control through manipulation of insect viruses.Analyses of the interactions among insect vectors,insect viruses and arboviruses will provide new opportunities for development of innovative strategies to control arbovirus transmission.

An efficient and safe strategy for germ cell-specific automatic excision of foreign DNA in F1 hybrid transgenic silkworms

The safety of transgenic technology is a major obstacle in the popularization and use of transgenic silkworms and their products.In sericulture,only the first filial generation(F1)hybrid eggs produced by cross-breeding Japanese and Chinese original strains are usually used for the large-scale breeding of silkworms,but this may result in uncontrolled transgene dispersal during the popularization and application of the F1 hybrid transgenic eggs.To address this issue,we developed a safe and efficient strategy using the GAL4/Upstream activating sequence(UAS)system,the FLP/flippase recognition target(FRT)system,and the gonad-specific expression gene promoters(RSHP1p and Nanosp)for the germ cell-specific automatic excision of foreign DNA in the F1 hybrid transgenic silkworms.We established 2 types of activator strains,R1p::GAL4-Gr and Nsp::GAL4-Gr,containing the testis-specific GAL4 gene expression cassettes driven by RSHP1p or Nanosp,respectively,and 1 type of effector strain,UAS::FLP-Rg,containing the UAS-linked FLP gene expression cassette.The FLP recombinase-mediated sperm-specific complete excision of FRT-flanked target DNA in the F1 double-transgenic silkworms resulting from the hybridization of R1p::GAL4-Gr and UAS::FLP-Rg was 100%,whereas the complete excision efficiency resulting from the hybridization of Nsp::GAL4-Gr and UAS::FLP-Rg ranged from 13.73%to 80.3%.Additionally,we identified a gene,sw11114,that is expressed in both testis and ovary of Bombyx mori,and can be used to establish novel gonad-specific expression systems in transgenic silkworms.This strategy has the potential to fundamentally solve the safety issue in the production of F1 transgenic silkworm eggs and provides an important reference for the safety of transgenic technology in other insect species.

Pollen analysis reveals the effects of uncovered interactions,pollen-carrying structures,and pollinator sex on the structure of wild bee-plant networks

Pollination networks are increasingly used to model the complexity of interactions between pollinators and flowering plants in communities.Different methods exist to sample these interactions,with direct observations of plant-pollinator contacts in the field being by far the most common.Although the identification of pollen carried by pollinators allows uncovering interactions and increasing sample sizes,the methods used to build pollen-transport networks are variable and their effect on network structure remains unclear.To understand how interaction sampling influences the structure of networks,we analyzed the pollen found on wild bees from eight communities across Mallorca Island and investigated the differences in pollen loads between bee body parts(scopa vs.body)and sexes.We then assessed how these differences,as well as the uncovered interactions not detected in the field,influenced the structure of wild bee-plant networks.We identified a higher quantity and diversity of pollen in the scopa than in the rest of the female body,but these differences did not lead to differences in structure between plant-pollination(excluding scopa pollen)and bee-feeding interaction(including scopa pollen)networks.However,networks built with pollen data were richer in plant species and interactions and showed lower modularity and specialization(H2'),and higher nestedness than visitation networks based on field observations.Female interactions with plants were stronger compared to those of males,although not richer.Accordingly,females were more generalist(low d')and tended to be more central in interaction networks,indicating their more key role structuring pollination networks in comparison to males.Our study highlights the importance of palynological data to increase the resolution of networks,as well as to understand important ecological questions such as the differences between plant-pollination and bee-feeding interaction networks,and the role of sexes in pollination.

Feeding behavior and hormoligosis associated with imidacloprid resistance in Asian citrus psyllid,Diaphorina citri

Imidacloprid is a neonicotinoid insecticide used for managing the Asian citrus psyllid,Diaphorina citri Kuwayama,which serves as vector of phytopathogens causing citrus greening.However,development of resistance to neonicotinoids among populations of D.citri has coincided with occasional control failures in the field.The objectives of this research were to(1)survey current levels of imidacloprid resistance in Florida citrus;(2)compare feeding behavior between imidacloprid-resistant and susceptible D.citri using electrical penetration graph recordings,and(3)investigate the possible amplification of insecticide hormoligosis associated with resistance.Field surveys confirmed that the susceptibility of D.citri populations to imidacloprid has decreased in commercial Florida citrus groves compared with a laboratory-susceptible population.Following 12 generations of selection,resistance to imidacloprid increased by 438 fold compared with the susceptible strain.Imidacloprid-susceptible D.citri feeding on citrus exhibited significantly more bouts associated with intercellular pathway(C),phloem penetration(D),phloem salivation(E1),and nonprobing(Np)activities than imidacloprid-resistant counterparts.However,there were no differences observed in the frequency or duration of phloem ingestion or xylem feeding between susceptible and resistant D.citri.There was no statistical difference in fecundity between resistant and susceptible strains.However,the fecundity of imidacloprid-susceptible female D.citri treated with a sublethal concentration of imidacloprid(LC_(25))increased significantly compared with controls,while such hormoligosis was less pronounced among imidacloprid-resistant psyllids.Our results suggest that imidacloprid-resistant psyllids may cease feeding sooner than susceptible counterparts following sublethal exposure to this insecticide,indicative of a behavioral resistance mechanism.

Body color plasticity of Diaphorina citri reflects a response to environmental stress

Body color polyphenism is common in Diaphorina citri.Previous studies compared physiological characteristics in D.citri,but the ecological and biological significance of its body color polyphenism remains poorly understood.We studied the ecological and molecular effects of stressors related to body color in D.citri.Crowding or low temperature induced a high proportion of gray morphs,which had smaller bodies,lower body weight,and greater susceptibility to the insecticide dinotefuran.We performed transcriptomic and metabolomics analysis of 2 color morphs in D.citri.Gene expression dynamics revealed that the differentially expressed genes were predominantly involved in energy metabolism,including fatty acid metabolism,amino acid metabolism,and carbohydrate metabolism.Among these genes,plexin,glycosidase,phospholipase,take out,trypsin,and triacylglycerol lipase were differentially expressed in 2 color morphs,and 6 hsps(3 hsp70,hsp83,hsp90,hsp68)were upregulated in gray morphs.The metabolome data showed that blue morphs exhibited a higher abundance of fatty acid and amino acid,whereas the content of carbohydrates was elevated in gray morphs.This study partly explains the body color polyphenism of D.citri and provides insights into the molecular changes of stress response of D.citri.

Genomics,transcriptomics,and peptidomics of the greater wax moth Galleria mellonella neuropeptides and their expression in response to lead stress

Neuropeptides are crucial in regulation of a rich variety of developmental,physiological,and behavioral functions throughout the life cycle of insects.Using an integrated approach of multiomics,we identified neuropeptide precursors in the greater wax moth Galleria mellonella,which is a harmful pest of honeybee hives with a worldwide distribution.Here,a total of 63 and 67 neuropeptide precursors were predicted and annotated in the G.mellonella genome and transcriptome,in which 40 neuropeptide precursors were confirmed in the G.mellonella peptidome.Interestingly,we identified 12 neuropeptide precursor genes present in G.mellonella but absent in honeybees,which may be potential novel pesticide target sites.Honeybee hives were contaminated with heavy metals such as lead,enabling its bioaccumulation in G.mellonella bodies through the food chain,we performed transcriptome sequencing to analyze the effects of Pb stress on the mRNA expression level of G.mellonella neuropeptide precursors.After treatment by Pb,the expression of neuropeptide F1 was found to be significantly downregulated,implying that this neuropeptide might be associated with responding to the heavy metal stress in G.mellonella.This study comprehensively identified neuropeptide precursors in G.mellonella,and discussed the effects of heavy metals on insect neuropeptides,with the example of G.mellonella.The results are valuable for future elucidation of how neuropeptides regulate physiological functions in G.mellonella and contribute to our understanding of the insect's environmental plasticity and identify potential new biomarkers to assess heavy metal toxicity in insects.

Research progress toward the influence of mosquito salivary proteins on the transmission of mosquito-borne viruses

Mosquito-borne viruses(MBVs)are a large class of viruses transmitted mainly through mosquito bites,including dengue virus,Zika virus,Japanese encephalitis virus,West Nile virus,and chikungunya virus,which pose a major threat to the health of people around the world.With global warming and extended human activities,the incidence of many MBVs has increased significantly.Mosquito saliva contains a variety of bioactive protein components.These not only enable blood feeding but also play a crucial role in regulating local infection at the bite site and the remote dissemination of MBVs as well as in remodeling the innate and adaptive immune responses of host vertebrates.Here,we review the physiological functions of mosquito salivary proteins(MSPs)in detail,the influence and the underlying mechanism of MSPs on the transmission of MBVs,and the current progress and issues that urgently need to be addressed in the research and development of MSP-based MBV transmission blocking vaccines.

Both host and diet shape bacterial communities of predatory mites

Microbial communities,derived from food,ambient,and inner,can affect host ecological adaption and evolution.Comparing with most phytophagous arthropods,predators may have more opportunities to develop specific microbiota depending on the level of prey specialization.To explore how diet sources affect host microbial communities and vary across predator species,we considered 3 types of predators from Phytoseiidae(Acari:Mesostigmata):polyphagous(Amblyseius orientalis Ehara,Neoseiulus barkeri Hughes,and Amblyseius swirski Athias-Henrio),oligophagous(Neoseiulus californicus McGregor),and monophagous(Phytoseiulus persimilis Athias-Henriot)predatory mites.The polyphagous species were fed on 2 types of diets,natural prey and alternative prey.By using 16S rRNA sequencing,we found that diet was the main source of microbiota in predatory mites,while there was no clear pattern affected by prey specialization.Among 3 polyphagous predators,host species had a larger impact than prey on microbial composition.Unlike A.orientalis or N.barkeri which showed consistency in their microbiota,prey switching significantly affectedβ-diversity of bacterial composition in A.swirskii,with 56%of the microbial alteration.In short,our results confirmed the substantial influence of diet on host microbial construction in predatory species,and highlighted species differences in shaping the microbiota which are not necessarily related to prey specialization.

Insect-specific RNA virus affects the stylet penetration activity of brown citrus aphid(Aphis citricidus)to facilitate its transmission

Sap-sucking insects often transmit plant viruses but also carry insect viruses,which infect insects but not plants.The impact of such insect viruses on insect host biology and ecology is largely unknown.Here,we identified a novel insect-specific virus carried by brown citrus aphid(Aphis citricidus),which we tentatively named Aphis citricidus picornavirus(AcPV).Phylogenetic analysis discovered a monophyletic cluster with AcPV and other unassigned viruses,suggesting that these viruses represent a new family in order Picornavirales.Systemic infection with AcPV triggered aphid antiviral immunity mediated by RNA interference,resulting in asymptomatic tolerance.Importantly,we found that AcPV was transmitted horizontally by secretion of the salivary gland into the feeding sites of plants.AcPV influenced aphid stylet behavior during feeding and increased the time required for intercellular penetration,thus promoting its transmission among aphids with plants as an intermediate site.The gene expression results suggested that this mechanism was linked with transcription of salivary protein genes and plant defense hormone signaling.Together,our results show that the horizontal transmission of AcPV in brown citrus aphids evolved in a manner similar to that of the circulative transmission of plant viruses by insect vectors,thus providing a new ecological perspective on the activity of insect-specific viruses found in aphids and improving the understanding of insect virus ecology.

Masculinizer gene controls sexual differentiation in Hyphantria cunea

The Masculinizer gene,Masc,encodes a lepidopteran-specific novel CCCHtype zinc finger protein,which controls sex determination and dosage compensation in Bombyx mori.Considering the potential application of it in pest control,it is necessary to investigate the function of Masc gene in Hyphantria cunea,a globally invasive forest pest.In the present study,we identified and functionally characterized the Masc gene,HcMasc,in H.cunea.Sequence analysis revealed that HcMASC contained the conserved CCCH-type zinc finger domain,nuclear localization signal,and male determining domain,in which the last was confirmed to be required for its masculinization in BmN cell line.However,expression data showed that unlike male-biased expression in B.mori,Hc-Masc gene expresses in main all developmental stages or tissues in both sexes.Clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9-based disruption of the common exons 1 and 3 of the HcMasc gene resulted in imbalanced sex ratio and abnormal external genitalia of both sexes.Our results suggest that the HcMasc gene is required for both male and female sexual differentiation and dosage compensation in H.cunea and provide a foundation for developing better strategies to control this pest.

Cross-resistance and genetics of field-evolved resistance to chlorfenapyr in Plutella xylostella

Chlorfenapyr is a broad-spectrum halogenated pyrrole insecticide with a unique mode of action.Due to the misuse and overuse of this chemical,resistance has been reported in several arthropods,including Plutella xylostella,which is one of the most destructive insect pests afflicting crucifers worldwide.A better understanding of the cross-resistance and genetics of field-evolved chlorfenapyr resistance could effectively guide resistance management practices.Here,the chlorfenapyr resistance of a fieldderived population of P xylostella was introgressed into the susceptible IPP-S strain using a selection-assisted multigenerational backcrossing approach.The constructed nearisogenic strain,TH-BCsF2,shared 98.4%genetic background with the recurrent parent IPP-S strain.The TH-BCsF2 strain showed 275-fold resistance to chlorfenapyr,but no significant cross-resistance to spinosad,abamectin,chlorpyrifos,β-cypermethrin,indoxacarb,chlorantraniliprole,or broflanilide(no more than 4.2-fold).Genetic analysis revealed that resistance was autosomal,incompletely dominant,and conferred by 1 major gene or a few tightly linked loci.The synergism of metabolic inhibitors(PBO,DEM,and DEF)to chlorfenapyr was very weak(<1.7-fold),and the metabolic enzyme activities in the TH-BCsF2 strain were not significantly elevated compared with the IPP-S strain.The results enhances our understanding of the genetic traits of chlorfenapyr resistance,and provides essential information for improving resistance management strategies.

MicroRNA let-7 targets BmCDK1 to regulate cell proliferation and endomitosis of silk gland in the silkworm,Bombyx mori

MicroRNAs play critical roles in multiple developmental processes in insects.Our previous study showed that CRISPR/Cas9-mediated knock down of the microRNA let-7 in silkworms increased the size of larvae and silk glands,thereby improving the silk production capacity.In this study,we elucidate the molecular mechanism underlying of let-7 regulates growth.Identification of differentially expressed genes in response to let-7 knock down revealed enrichment of pathways associated with cell proliferation and DNA replication.let-7 dysregulation affected the cell cycle and proliferation of the Bombyx mori cell line BmN.Dual-luciferase and target site mutation assays showed that BmCDK1 is a direct target gene of let-7,with only 1 binding site on its 3′-untranslated region.RNA interference of BmCDK1 inhibited cell proliferation,but this effect was counteracted by co-transfection with let-7 antagomir.Moreover,let-7 knock down induced BmCDK1 expression and promoted cell proliferation in multiple tissues,and further induced endomitosis in the silk gland in vivo.Knock down of BmCDK1 resulted in abnormal formation of a new epidermis,and larval development was arrested at the 2nd or 3rd molt stage.Taken together,our results demonstrated that BmCDK1 is a novel target of let-7 in cell fate determination,possessing potential for improving silk yield in silkworm.

Deciphering the cellular heterogeneity of the insect brainwith single-cell RNA sequencing

Insects show highly complicated adaptive and sophisticated behaviors, includ-ing spatial orientation skills, learning ability, and social interaction. These behaviors arecontrolled by the insect brain, the central part of the nervous system. The tiny insect brainconsists of millions of highly differentiated and interconnected cells forming a complexnetwork. Decades of research has gone into an understanding of which parts of the insectbrain possess particular behaviors, but exactly how they modulate these functional conse-quences needs to be clarified. Detailed description of the brain and behavior is required todecipher the complexity of cell types, as well as their connectivity and function. Single-cell RNA-sequencing (scRNA-seq) has emerged recently as a breakthrough technologyto understand the transcriptome at cellular resolution. With scRNA-seq, it is possible touncover the cellular heterogeneity of brain cells and elucidate their specific functions andstate. In this review, we first review the basic structure of insect brains and the links toinsect behaviors mainly focusing on learning and memory. Then the scRNA applicationson insect brains are introduced by representative studies. Single-cell RNA-seq has allowedresearchers to classify cell subpopulations within different insect brain regions, pinpointsingle-cell developmental trajectories, and identify gene regulatory networks. These devel-opments empower the advances in neuroscience and shed light on the intricate problemsin understanding insect brain functions and behaviors.

Acetyl coenzyme A carboxylase modulates lipogenesis and sugar homeostasis in Blattella germanica

Lipid and sugar homeostasis is critical for insect development and survival.In this study,we characterized an acetyl coenzyme A carboxylase gene in Blattella germanica(BgACC)that is involved in both lipogenesis and sugar homeostasis.We found that BgACC was dominantly expressed in the fat body and integument,and was significantly upregulated after molting.Knockdown of BgACC in 5th-instar nymphs did not affect their normal molting to the next nymphal stage,but it caused a lethal phenotype during adult emergence.BgACC-RNA interference(RNAi)significantly downregulated total free fatty acid(FFA)and triacylglycerol(TAG)levels,and also caused a significant decrease of cuticular hydrocarbons(CHCs).Repression of BgACC in adult females affected the development of oocytes and resulted in sterile females,but BgACC-RNAi did not affect the reproductive ability of males.Interestingly,knockdown of BgACC also changed the expression of insulin-like peptide genes(BglLPs),which mimicked a physiological state of high sugar uptake.In addition,BgACC was upregulated when B.germanica were fed on a high sucrose diet,and repression of BgACC upregulated the expression of the glycogen synthase gene(BgGlyS).Moreover,BgACC-RNAi increased the circulating sugar levels and glycogen storage,and a longevity assay suggested that BgACC was important for the survival of B.germanica under conditions of high sucrose uptake.Our results confirm that BgACC is involved in multiple lipid biogenesis and sugar homeostasis processes,which further modulates insect reproduction and sugar tolerance.This study benefits our understanding of the crosstalk between lipid and sugar metabolism.

Fatty acids derived from oviposition systems guide female black soldier flies(Hermetia illucens)toward egg deposition sites

The black soldier fly,Hermetia illucens,comes with big promises for industrial purposes since its larvae feed polyphagously on a broad spectrum of organic substrates.However,research focusing on adult flies is scarce,which is inconsistent with their reproductive relevance within the rearing cycle.In particular,directed oviposition is a challenge in artificial systems.Currently,decomposing organic matter is commonly used as oviposition substrate,which has extensive potential for improvement in view of the lack of standardization and the risk of microbial contamination.Here,we identified three fatty acids and one fatty acid methyl ester derived from the surface of old oviposition sites and targeted to elucidate their effect on preference behavior and oviposition site selection using Y-olfactometry and prepared oviposition sites,respectively.Exposure to tetradecanoic acid attracted gravid females and stimulated oviposition most strongly,while decanoic acid demonstrated a repulsive effect.Females kept in mixed-sex populations were attracted by tetradecanoic acid,resulting in a higher egg mass found in the compound box(3.0–11.4 fold),a≥2.3 fold reduction of nonspecifically deposited eggs,and the highest total egg mass.Conversely,decanoic and dodecanoic acid caused females to lay a greater proportion of eggs nonspecifically outside both boxes.Our data suggest that fatty acids,especially tetradecanoic acid,are important cues for oviposition site selection in black soldier flies.In order to achieve a directed oviposition behavior,the role of further short-and long-chain fatty acids as attractants should be examined.