Spodoptera exigua Hübner is one of the most important agricultural pests in Thailand. The present study investigated the toxicity of crude extracts and phenylpropanoid compounds of A. galanga (Zingiberaceae) against S. exigua. After 24 h of a topical application bioassay on secondary instar larvae, the ethyl acetate extract estimation of the LD50 of A. galanga (Zingiberaceae) showed toxicity toward secondary instar S. exigua larvae (LD50 ~ 2.44 µg/larva). Phenylpropanoid compounds were isolated from the ethyl acetate A. galanga crude extract which has [1’S]-1’-acetoxychavicol acetate as highest toxicity (LD50 of 1.93 µg/larvae). [1’S]-1’-acetoxychavicol acetate also showed carboxylesterase activity inhibition. Thus, the ethyl acetate extract of A. galanga may have [1’S]-1’-acetoxychavicol acetate as an active ingredient for controlling this pest, which could be used as an alternative to application of environmentally insecticides for controlling S. exigua.

中文翻译：

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高良姜（姜科）提取物中苯丙烷类化合物对甜菜夜蛾（鳞翅目：夜蛾科）的毒性

Spodoptera exigua Hübner 是泰国最重要的农业害虫之一。本研究调查了 A. galanga（姜科）的粗提取物和苯丙烷类化合物对 S. exigua 的毒性。在对二龄幼虫进行局部应用生物测定 24 小时后，高良姜（姜科）的 LD50 的乙酸乙酯提取物估计显示对二龄 S. exigua 幼虫具有毒性（LD50 ~ 2.44 µg/幼虫）。从乙酸乙酯 A. galanga 粗提取物中分离出苯丙烷类化合物，其中 [1'S]-1'-乙酰氧基茶酚乙酸酯的毒性最高（LD50 为 1.93 µg/幼虫）。[1'S]-1'-乙酰氧基茶酚乙酸酯也显示出羧酸酯酶活性抑制。因此，高良姜的乙酸乙酯提取物可能含有[1'S]-1'-乙酰氧基茶酚乙酸酯作为防治该害虫的活性成分，