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BACKGROUND: Insect pheromones and host volatiles are important for pest control due to their high efficiency and low potential for environmental pollution. The functions of myrtenol, myrtanol and myrtenal in pest–host interactions are unknown. This study aimed to determine the presence of myrtenol, myrtanol and myrtenal in newly emerged and emerged stages of Dendroctonus armandi, and in infected and healthy Pinus armandi, and to identify their roles in tree protection and pest management based on electroantennography (EAG), Y‐tube and toxicity experiments. RESULTS: Gas chromatographic and mass spectrometry (GC–MS) analyses, EAG, Y‐tube and toxicity assays revealed the following: (1) myrtenol was found in P. armandi phloem and did not exhibit significant toxicity towards D. armandi; (2) myrtanol was produced by infected P. armandi after D. armandi invasion and had significant toxicity towards D. armandi, especially females; and (3) myrtenal might represent an aggregation pheromone produced by female D. armandi to exert aggregation effects on other females, to help them overcome the resistance of P. armandi jointly and ensure a successful invasion, females remained in an aggregation state from leaving the host to mating in a new host. CONCLUSION: These findings suggest that myrtanol as a repellent has potential for the protection of P. armandi and that myrtenal could be used to trap and disorient D. armandi. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Bark beetles rely on detoxifying enzymes to resist the defensive terpenoids of their host trees. Research on carboxylesterases (CarEs) has focused on their multiple functions in the metabolic detoxification of pesticides and plant allelochemicals, drug resistance, and juvenile hormone and pheromone degradation. RESULT: We identified eight new CarE genes in the Chinese white pine beetle (Dendroctonus armandi) and carried out bioinformatics analysis on the deduced full‐length amino acid sequences. Differential transcript levels of CarE genes were observed between sexes; within these levels, significant differences were found among the different development stages, and between insects fed on the phloem of Pinus armandi and exposed to five stimuli [(−)‐α‐pinene, (−)‐β‐pinene, (+)‐3‐carene, limonene and turpentine] at 8 and 24 h. CONCLUSION: Transcription levels of CarE genes suggest some relationship with the detoxification of terpenoids released by host trees. The functions of bark beetle esterase are mainly in hydrolyzing the host chemical defense and degrading odorant molecules during host selection and colonization. © 2018 Society of Chemical Industry The functions of bark beetle esterase are mainly to hydrolyze the host chemical defense and degrade odorant molecules during host selection and colonization. [ABSTRACT FROM AUTHOR]

BACKGROUND Bark beetles rely on their detoxifying enzymes to resist the defensive terpenoids of host trees. Glutathione S-transferases ( GSTs) conjugate xenobiotic compounds with a glutathione moiety ( GSH) and often work in tandem with cytochromes P450 or other enzymes that aid in the detoxification, sequestration or excretion of toxic compounds. RESULT We identified nine new GST genes in the Chinese white pine beetle ( Dendroctonus armandi) and carried out a bioinformatics analysis on the deduced full-length amino acid sequences. These genes belong to four different classes (epsilon, sigma, omega and theta). Differential transcript levels of each class of GST genes were observed between sexes, and, within these levels, significant differences were found among the different adult substages that were fed phloem of Pinus armandi and exposed to six stimuli [(±)- α-pinene, (−)- α-pinene, (−)- β-pinene, (+)-3-carene, (±)-limonene and turpentine] at 8 and 24 h. CONCLUSION The increased transcription levels of GST genes suggested that they have some relationship with the detoxification of terpenoids that are released by host trees. The mediating oxidative stress that is caused by monoterpene might be the main role of the bark beetle GSTs. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]