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.

Comparison of larval performance and oviposition preference of Spodoptera frugiperda among three host plants:Potential risks to potato and tobacco crops

Fall armyworm(FAW),Spodoptera frugiperda(J.E.Smith),is a majorpolyphagous pest with the potential to seriously damage various crops.A better under-standing of FAW's performance on different hosts may help to predict which plants willbe attacked when the preferred host is absent,and facilitate the development of effectivepest management practices.We compared the larval performance of FAW fed on maizewith that of FAW fed on potato and tobacco,which are important crops in China,usingan age-stage two-sex life table and adult female oviposition preference experiments.Incage experiments with potato,tobacco,or maize as the host,FAW reared on maize exhib-ited the strongest performance with shorter developmental time in thc larval stage,longerlongevity,and a higher reproductive rate in adults.Females oviposited on maize in pref-erence to potato or tobacco.Compared with larvae fed on maize,those fed on potato andtobacco exhibited significantly lower survival,with only 31.61%and 8.13%developing tothe adult stage,respectively.Several life table parameters,including the mean generationtime(T),net reproductive rate(R^(0)),finite rate of increase(λ),and intrinsic rate of nat-ural increase(r)were negatively affected in FAW fed on potato and tobacco.Our resultssupport the preference-performance hypothesis,that is,that herbivore females maximizefitness by choosing host plants associated with strong larval performance.Although lar-vae and adults performed poorly on potato and tobacco,their offspring will be capable ofcstablishing populations on them,posing a potential threat to these crops in China.

Rho 1 participates in parasitoid wasp eggs maturation and host cellular immunity inhibition

Endoparasitoid wasps introduce venom into their host insects during the egglaying stage.Venom proteins play various roles in the host physiology,development,immunity,and behavior manipulation and regulation.In this study,we identified a venom protein,MmRhol,a small guanine nucleotide-binding protein derived from ovary in the endoparasitoid wasp Microplitis mediator and found that knockdown of its expression by RNA interference caused down-regulation of vitellogenin and juvenile hormone,egg production,and cocoons formation in the female wasps.We demonstrated that MmRho1 entered the cotton bollworm's(host)hemocytes and suppressed cellular immune responses after parasitism using immunofluorescence staining.Furthermore,wasp MmRhol interacted with the cotton bollworm's actin cytoskeleton rearrangement regulator diaphanous by yeast 2-hybrid and glutathione s-transferase pull-down.In conclusion,this study indicates that MmRho1 plays dual roles in wasp development and the suppression of the host insect cellular immune responses.