Monoterpenoid signals and their transcriptional responses to feeding and juvenile hormone regulations in bark beetle Ips hauseri Reitter.

Abstract

Hauser s engraver beetle Ips hauseri Reitter is a serious pest in spruce forest ecosystems in Central Asia. Its monoterpenoid signal production, transcriptome responses, and potential regulatory mechanisms remain poorly understood. The quality and quantity of volatile metabolites in hindgut extracts of I. hauseri were found to differ between males and females and among three groups: beetles that are newly emerged, those with a topical application of juvenile hormone III (JHIII), and those that have been feeding for 24 h. Feeding males definitively dominate monoterpenoid signal production in I. hauseri, which uses (4S)-(-)-ipsenol and (S)-(-)-cis-verbenol to implement reproductive segregation from I. typographus and I. shangrila Feeding stimulation can induce higher expression of most genes related to the biosynthesis of (4S)-(-)-ipsenol than JHIII induction, and it shows a male-specific mode in I. hauseri JHIII can stimulate males to produce large amounts of (-)-verbenone and also upregulates a higher expression of several CYP6 genes in males than females. The expression of genes involved in the metabolism of JHIII in females and males were found to be upregulated. A species-specific aggregation pheromone system for I hauseri, consisting of (4S)-(-)-ipsenol and S-(-)-cis-verbenol, can be used to monitor population dynamics or mass trap killing. Our results also enable a better understanding of the bottom-up role of feeding behaviors in mediating population reproduction/aggregation and interspecific interactions.