Function of mevalonate pathway genes in the synthesis of frontalin in Chinese white pine beetle,Dendroctonus armandi(curculionidae: Scolytinae)

Abstract

The Chinese white pine beetle (Dendroctonus armandi Tsai and Li) is a significant pest of pine forests in the Qinling and Bashan Mountains of China. Adult males commonly produce frontalin using precursors synthesized through the mevalonate pathway, which is regulated by juvenile hormone III (JHIII). In this study, the expression levels of mevalonate pathway genes were quantified after phloem feeding and topical application of the JHIII solution. The frontalin was quantified by gas chromatography-mass spectrometry. Both the phloem feeding and JHIII treatments produced an evident upregulation in the male gut, mainly in 3-hydroxy-3methylglutaryl-CoA synthase (HMGS) and 3-hydroxy-3methylglutaryl-CoA reductase (HMGR). Moreover, HMGS, HMGR, isopentenyl diphosphate isomerase, and geranyl diphosphate synthase/farnesyl diphosphate synthase were upregulated in fed and JHIII-stimulated males of D. armandi under both conditions (solitary and paired). The expression levels were higher in paired compared to solitary males.Males had higher expression levels compared with females. Correspondingly, the phloem-feeding males produced more frontalin than JHIII-treated males, and the production of frontalin was higher in paired males than in solitary males. The knockdown of mevalonate pathway genes using RNAi in vivo effectively reduced the messenger RNA level of these genes and inhibited the production of frontalin. Among them, the silencing of HMGR or HMGS genes reduced the synthesis of frontalin most significantly.

Roles of Krüppel Homolog 1 and Broad-Complex in the Development of Dendroctonus armandi (Coleoptera: Scolytinae)

“…RNA interference (RNAi) technology has now become a widely used tool to analyze the gene functions of Chinese white pine beetle ( Dendroctonus armandi Tsai and Li). Chen‘s team used RNAi to investigate and analyze the olfactory receptor coreceptor ( DarmOrco ), chemoreceptor ( DarmCSP2 ), aquaporins ( DaAqps ), antifreeze protein genes ( DaAFP ), Capa peptide receptors ( DaCapaRs ), neuropeptide F ( DaNPF ), and 3-hydroxy-3-methylglutaryl coenzyme A reductase genes ( HMGR ) in D. armandi ( Zhang et al, 2016 ; Li et al, 2018 ; Fu et al, 2019 , 2020 , 2021 ; Liu et al, 2021 ; Sun et al, 2021 ). Sun et al (2022) discovered that allatostatin C (PISCF/AST) and juvenile hormone acid O-methyltransferase ( JHAMT ) were major regulators of juvenile hormone synthesis in D. armandi after obtaining dsRNA technology via the L4440 vector construction.…”

Identifying optimal reference genes for gene expression studies in Eurasian spruce bark beetle, Ips typographus (Coleoptera: Curculionidae: Scolytinae)

“…To examine the effect of temperature treatment, the freshly emerged adults were exposed to 4, 27, and 37 °C for 72 h. For the juvenile hormone treatment (JHIII), fed adult male and female beetles were treated topically on the ventral surface of the abdomen with 10 µg JHIII (Sigma-Aldrich, St. Louis, MO, USA) and acetone as control 47 , 48 . Beetles were maintained in similar conditions as mentioned above for 72 h. Wild beetles (adults) were collected from the infested Norway spruce stands from Kostelec nad Cernými lesy, Czech Republic, to examine the climatic effect.…”

Reference Gene Selection for Normalizing Gene Expression in Ips Sexdentatus (Coleoptera: Curculionidae: Scolytinae) Under Different Experimental Conditions

“…For JHIII treatment, emerged beetles were sorted based on gender and kept at 4°C on moist paper towels. Beetles were treated topically on the ventral surface of the abdomen with 10 μg JHIII (dissolved in acetone) (Sigma-Aldrich, St. Louis, MO, USA) and only acetone as control (Aw et al, 2010 ; Sun et al, 2021 ). The beetles were incubated at 27 ± 1°C under 70 ± 5% humidity and a 16:8-h light/dark (L:D) photoperiod in groups of 20 in 60 ml plastic containers for 72 h. After incubation, beetles were immediately shock frozen in liquid nitrogen and stored at −80°C for downstream processing.…”

“…For JHIII treatment, emerged beetles were sorted based on gender and kept at 4 • C on moist paper towels. Beetles were treated topically on the ventral surface of the abdomen with 10 µg JHIII (dissolved in acetone) (Sigma-Aldrich, St. Louis, MO, USA) and only acetone as control (Aw et al, 2010;Sun et al, 2021).…”