Metabolome and Transcriptome Analysis Reveals the Effects of Host Shift on Dendrolimus houi Lajonquiere Larvae

Dendrolimus houi Lajonquiere is one of the most prevalent pine caterpillars in southern China, causing overwhelming forest infestation. It can overcome the negative impact of host shift from the original host, Cryptomeria fortune, to other tree species to complete its life cycle. In this work, D. houi larvae (1st to 3rd instar), originally feeding on C. fortunei needles, were used to determine the changes in the growth and development after they moved to needles of Cupressus funebris and Pinus yunnanensis during their 4th to 5th instar. Metabonomics and transcriptomics were conducted to evaluate the effects of the host shift on metabolite accumulation and gene expression of D. houi larvae. The results showed that the host shift significantly inhibited the pest growth and development by extending developmental duration and minifying the body length, body weight and head shell width. Besides, we found that the host shift influenced steroid hormone biosynthesis in D. houi larvae, which might lead to their abnormal development. The results may help to understand the response of D. houi larvae to host shift, and their adaptation mechanism to different hosts during multiple life cycles, providing a new plantation mode for mixed forests to suppress D. houi as well.