Monoterpenoid signals and their transcriptional responses to feeding and juvenile hormone regulation in bark beetle Ips hauser i

Abstract

Hauser's engraver beetle, Ips hauseri, 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 were newly emerged, those with a topical application of juvenile hormone III (JHIII) and those that had been feeding for 24 h. Feeding males definitively dominated monoterpenoid signal production in I. hauseri, which uses (4S)-(−)-ipsenol and (S)-(−)-cis-verbenol to implement reproductive segregation from Ipstypographus and Ipsshangrila. Feeding stimulation induced higher expression of most genes related to the biosynthesis of (4S)-(−)-ipsenol than JHIII induction, and showed a male-specific mode in I. hauseri. JHIII stimulated males to produce large amounts of (−)-verbenone and also upregulated the expression of several CYP6 genes, to a greater extent in males than in females. The expression of genes involved in the metabolism of JHIII in females and males was also found to be upregulated. Our results indicate that 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.

Exposure to artificial light at night mediates the locomotion activity and oviposition capacity of Dastarcus helophoroides (Fairmaire)

“…The circadian rhythms of reproductive functions, such as courtship, mating, and gamete production, were regulated by oscillations in JH titers. In cockroaches and bark beetles, oscillations in JH titers mediated the production or release of sex pheromones to influence female or male calling signals ( Kang et al, 2019 ; Fang et al, 2021 ; Chen et al, 2022 ). Moreover, melatonin has been identified in many insect tissues, including the head, brain, and compound eyes ( Guy et al, 2013 ).…”

Insights into the Divergence of Chinese Ips Bark Beetles during Evolutionary Adaptation

“…In each species, these pheromones consist of different blends of chemicals that are usually species specific, and the attractant pheromones of one species may exert a repellent effect on other species, which is closely associated with reproductive isolation [9,27]. The aggregation pheromones of nine Chinese Ips species have been identified [28][29][30][31][32][33][34][35][36][37][38], and Ips bark beetles mainly use host monoterpenes as biosynthetic precursors of aggregation pheromones [39] or synthesize them de novo via the mevalonate pathway [40,41]. For example, as major components of the aggregation pheromone of Ips bark beetles, ipsenol and ipsdienol are biosynthesized de novo [40], while the pheromonal verbenols are derived from host α-pinene [41].…”