Sex dependent transcriptomic and reproductive response of the diamondback moth (Plutella xylostella) to cold stress
Temperature has fundamental influences on fitness and distribution of insects. There have been very few studies on effects of mild cold conditions on insects. We found Plutella xylostella had reduced fitness and females produced few viable eggs when reared at 10°C, a temperature at which they can complete development. Male moths reared at 10°C were not able to fertilize eggs, but the eggs produced by female moths reared at this temperature were viable and could be fertilisied by males moths reared at a warmer temperature (25°C). Subsequently, we examined the transcriptomic changes in mid-fourth instar female and male larvae reared at 10°C and 25°C to investigate sex-dependent developmental and physiological responses of P. xylostella to the mild cold stress. We found 624 differentially expressed genes (DEGs) in females, the majority of which were down-regulated. In males 3239 genes were dysregulated and the majority were up-regulated. Only 280 DEGs were common to both sexes. In females, no DEGs encoded heat shock or cold shock proteins, but some of the DEGs in males did encode these proteins. These differences might suggest that female and male adopt some different strategies in coping with cold stress and/or they were passively affected by coldness to different degrees and in different ways. In addition, DEGs encoding antimicrobial peptides, cytochrome P450 monooxygenases, fatty acid-related enzymes, cuticle proteins, myofilament, and hormone-related proteins were found in both sexes under cold stress. The transcriptome study reveals unexpected sex-dependent thermal responses and provides much new information of how insects that do not diapause cope with a decreased temperature Overall design: 12 RNAseq libararies. Variables: larval sex (Male and female) and rearing temparture (10 C and 25 C). 3 biological replicates for each traetment.