The detoxification enzymes superfamilies of cytochrome P450 (P450), glutathione S‐transferase (GST) and carboxylesterase (CoE) play important roles in the metabolism of xenobiotics and endogenous substrates. Despite their importance in insect physiology and ecology, the relative activities of these enzyme systems among developmental stages, sexes and tissues of insect species have not been studied extensively. In the present study, we determine the relative activities of these enzymes in eggs, larval stages, adults of each sex and different tissues of the Japanese beetle (Popillia japonica Newman) in response to model exogenous substrates. The effect of food deprivation on enzyme activities is also examined in adult gut tissue. In this scarab species, ontogeny influences enzyme activities and catalytic efficiency, with eggs exhibiting only GST activity, first‐instar larvae exhibiting GST and CoE activities, and other life stages exhibiting P450 7‐ethoxycoumarin O‐deethylation (ECOD), GST and CoE activities. Second‐instar larvae have the highest GST activity, whereas third‐instar larvae have the highest P450 and CoE activities. Male and female adults show differences in P450 ECOD activity but not in CoE activity. Adult tissues vary in enzyme activities, with midgut tissues having the greatest P450 ECOD and CoE activities. A feeding bout of 24 h induces the optimal activities of P450 ECOD, GST and CoE in the gut of adult beetles. Interestingly, activity of GST is induced upon prolonged starvation. The findings of the present study highlight the apparent importance and contribution of detoxification enzymes in the physiology and ecology of this economically‐important pest.

中文翻译：

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个体发育、性别和成虫组织影响日本甲虫（Popillia japonica Newman）解毒酶的活性

细胞色素 P450 (P450)、谷胱甘肽 S-转移酶 (GST) 和羧酸酯酶 (CoE) 的解毒酶超家族在外源性物质和内源性底物的代谢中起重要作用。尽管它们在昆虫生理学和生态学中很重要，但这些酶系统在昆虫物种的发育阶段、性别和组织中的相对活性尚未得到广泛研究。在本研究中，我们确定了这些酶在日本甲虫（Popillia japonica Newman）的卵、幼虫阶段、各种性别的成虫和不同组织中的相对活性，以响应模型外源底物。在成人肠道组织中也检查了食物剥夺对酶活性的影响。在这种金龟子物种中，个体发育影响酶活性和催化效率，卵仅表现出 GST 活性，一龄幼虫表现出 GST 和 CoE 活性，其他生命阶段表现出 P450 7-乙氧基香豆素 O-脱乙基（ECOD）、GST 和 CoE 活性。二龄幼虫的 GST 活性最高，而三龄幼虫的 P450 和 CoE 活性最高。男性和女性成年人在 P450 ECOD 活动中表现出差异，但在 CoE 活动中没有表现出差异。成体组织的酶活性各不相同，中肠组织具有最大的 P450 ECOD 和 CoE 活性。24 小时的喂食会诱导成年甲虫肠道中 P450 ECOD、GST 和 CoE 的最佳活性。有趣的是，长期饥饿会诱导 GST 的活动。