A Neural Circuit Controlling Virgin Female Aggression Induced by Mating-related Cues in Drosophila

Females increase aggression for mating opportunities and for acquiring reproductive resources.Although the close relationship between female aggression and mating status is widely appreciated,whether and how female aggression is regulated by mating-related cues remains poorly understood.Here we report an interesting observation that Drosophila virgin females initiate high-frequency attacks toward mated females.We identify 11-cis-vaccenyl acetate(cVA),a male-derived pheromone transferred to females during mating,which promotes virgin female aggression.We subsequently reveal a cVA-responsive neural circuit consisting of four orders of neurons,including Or67d,DA1,aSP-g,and pC1 neurons,that mediate cVA-induced virgin female aggression.We also determine that aSP-g neurons release acetylcholine(ACh)to excite pC1 neurons via the nicotinic ACh receptor nAChRα7.Together,beyond revealing cVA as a mating-related inducer of virgin female aggression,our results identify a neural circuit linking the chemosensory perception of mating-related cues to aggressive behavior in Drosophila females.

The structure of the compound eyes and phototaxis in two phenotypes of the bean pest Callosobruchus maculatus(Coleoptera:Bruchinae)

Callosobruchus maculatus(Fabricius,1775)(Coleoptera:Bruchinae)is a destructive agricultural pest that is harmful to beans worldwide and an important quarantine pest in China.It was divided into two phenotypes based on polyphenism:normal and flight forms.In this study,we first compared the morphological structures of the compound eyes of the two forms.According to the results of scanning electron microscopy(SEM),transmission electron microscopy(TEM),microcomputed tomography(micro-CT),and computer three-dimensional reconstruction,there are no differences in the structures of the compound eyes between the normal and flight forms except for the number of ommatidia.From the internal structure,the compound eyes have a biconvex cornea with open rhabdom and acone eye,crystalline cone directly connected with rhabdom,and no clear zone.It is a kind of apposition eye.Ommatidia facets range in shape from quadrilateral to hexagonal and some irregular shapes.On electroretinograms(ERGs),the normal and flight forms showed different spectral sensitivities:the normal form had the strongest response to ultraviolet light,whereas the flight form had the strongest response to white light.Behavioral assays revealed that the normal and flight forms showed completely opposite phototaxis behaviors;the flight form exhibited positive phototaxis,whereas the normal form exhibited negative phototaxis.This study not only enriches our knowledge on coleopteran compound eyes but also provides a foundation for in-depth research on the photoreceptor mechanisms of compound eyes,which may be useful in pest control management.

Serotonin Signaling Modulates Sexual Receptivity of Virgin Female Drosophila

The choice of females to accept or reject male courtship is a critical decision for animal reproduction.Serotonin(5-hydroxytryptamine;5-HT)has been found to regulate sexual behavior in many species,but it is unclear how 5-HT and its receptors function to regulate different aspects of sexual behavior.Here we used Drosophila melanogaster as the model animal to investigate how 5-HT and its receptors modulate female sexual receptivity.We found that knockout of tryptophan hydroxylase(Trh),which is involved in the biosynthesis of 5-HT,severely reduced virgin female receptivity without affecting post-mating behaviors.We identified a subset of sexually dimorphic Trh neurons that co-expressed fruitless(fru),in which the activity was correlated with sexual receptivity in females.We also found that 5-HT1A and 5-HT7 receptors regulate virgin female receptivity.Our findings demonstrate how 5-HT functions in sexually dimorphic neurons to promote virgin female receptivity through two of its receptors.

Dual Effects of Light on Regulating Aedes aegypti Heat-Seeking Behavior

Dear Editor,Mosquitoes,as important arthropod disease vectors,efficiently transmit pathogens such as dengue virus,Zika virus,yellow fever virus,and malaria.To find their host,female mosquitoes use multiple sensory systems to detect host-associated cues such as CO_(2),volatile odorants,visual signals,and temperature.