Modulation of fatty acid elongation in cockroaches sustains sexually dimorphic hydrocarbons and female attractiveness

Abstract

Insect ceatisceucloanrfhirymdtrhoactaalrlbhoenadsi(nCglHeCvesls)asreerrveepraesseinmtepdocrotarrnetcitnlyte: Rsexual signaling chemicals and generally show variation between the sexes, but little is known about the generation of sexually dimorphic hydrocarbons (SDHCs) in insects. InAUthi:sPslteuadsyec, hweeckrwepheotrhtetrhtehemedoiltestcouthlaersentenceInthisstudy; mechanism and biological significance that underlie the generation of SDHC in the German cockroach Blattella germanica. Sexually mature females possess more C29 CHCs, especially the contact sex pheromone precursor 3,11-DimeC29. RNA interference (RANUAi): SPclereaesennotethatRNAihasbeendefinedasRNAinterferenceinsentencesRNAinterference RNAi screenagainstthe:::against the fatty acid elongase family members combined with heterologous expression of the genes in yeast revealed that both BgElo12 and BgElo24 were involved in hydrocarbon (HACU) p:roPdleuacsteionno,tebthuat tBHgCEhlaos2b4eeisndoeffwinieddeacshaytadlryotcicarabcotniviintiseesntaenncdeissRaNbAleinttoerpferroevnidcee RsuNbAsit rsactreesenagainstthe:::for BgElo12, and only the female-enriched BgElo12 is responsible for sustaining femalespecific HC profile. Repressing BgElo12 masculinized the female CHC profile, decreased contact sex pheromone level, and consequently reduced the sexual attractiveness of female cockroaches. Moreover, the asymmetric expression of BgElo12 between the sexes is modulated by sex differentiation cascade. Specifically, male-specific BgDsx represses the transcription of BgElo12 in males, while BgTra is able to remove this effect in females. Our study reveals a novel molecular mechanism responsible for the formation of SDHCs and also provide evidences on shaping of the SDHCs by sexual selection, as females use them to generate high levels of contact sex pheromone.