Abstract:  Heat shock proteins (HSPs) play an important role in the stress stimulation of insects. In order to study the HSP gene family of Plutella xylostella, 25 HSP genes, including 2 HSP90, 8 HSP70 and 15 sHSP （small heat shock protein， sHSP） genes, were identified from the P. xylostella genome by comparison with the HSP genes from the Bombyx mori genome using local Blast program. Phylogenetic analysis of the HSP genes from the genomes of P. xylostella, B. mori, Drosophila melanogaster and Tribolium castaneum revealed that sHSPs are species-specific, but HSP70 proteins are more conserved than sHSPs in insects. The analysis of expression patterns of HSP genes from P. xylostella revealed that the insecticide resistant-strains had different expression patterns of HSP genes from the susceptible strain. The expression patterns of HSP genes among the 1st, 2nd and 3rd instar larvae were similar, but their expression patterns were different from that in the 4th instar larva. The expression patterns of HSP genes between the 4th instar larva and pupa were similar, while those between male and female adults were significantly different. The expression of two sHSP genes ［CCG003980.1 (Px23.5) and CCG005412.2 (Px27.5)］ was up-regulated significantly in male adults compared to female adults, which were identified with a function of sperm production in D. melanogaster. The results indicate that HSPs may play an important role not only in pesticide resistance, development and metamorphosis, but in reproduction in insects. This study provides a foundation for further studies on the interactions between HSPs and the development and stress resistance of P. xylostella.

Key words:  Plutella xylostella, heat shock protein (HSP), comparative genomics, pesticide resistance, gene expression pattern