Enhancing Effect Of Chenopodium Ambrosioides Essential Oil On The Selected Insecticides Penetration Through Cuticula Of Plutella Xylostella Larvae

Chenopodium ambrosioides L (Chenopodiaceae) originated from South America, is an annual plant with a strong aromatic odor and is widely distributed in hot sub-tropical and tropical as well as in temperate regions. In China, it is distributed in Fujian, Jiangxi, Zhejiang, Jiangsu, Taiwan, Guangdong, Guangxi provinces etc.This paper deals mainly with the influence of Chenopodium ambrosiodes essential oil on the toxicity to Plutella xylostella larvae and on the activities of acetylcholinesterase (AChE), carboxylesterase (CarE), glutathione-S-tranferase (GSTs) of the insect. Cuticula morphology of P. xylostella larvae, treated with C. ambrosioides essential oil, was investigated by scanning electron microscopy, and insecticide dose, penetrating through insect cuticula, was investigated by gaschromotagraphy(GC-MS).Dropping bioassay showed that C. ambrosioides essential oil could significantly enhance the toxicity of trichlorphon,fiproni,chlorpyrifos to P. xylostella larvae, which resulted in LD₅₀ ratio of 0．4808, 0．6766, 0．7973, respectively, compared with those before treatment. However, the oil could reduce the toxicity of endosulfan, which resulted in LD₅₀ ratio of 1．3849．There were no significant difference between toxicity of methomyl, emamectin benzoate, bifenthrin, dichlorvos, beta-Cypermethrin and the LD₅₀ ratio were 0．9759, 0．9837, 0．9918, 1．0101 and 1．0152, respectively.Leaf-sandwich bioassay showed that C. ambrosioides essential oil could significantly enhance the toxicity of methomyl,chlorpyrifos,fipronil and bifenthrin to P. xylostella larvae, which resulted in LD₅₀ ratio of 0．4784, 0．5012, 0．6609, 0．7358, respectively, compared with those before treatment. However, the oil reduced the toxicity of emamectin benzoate and trichlorphon, which resulted in LD₅₀ ratio of 2．2005, 2．4404, respectively.Leaf-dip bioasay showed that C. ambrosioides essential oil could significantly enhance the toxicity of fipronil, bifenthrin, emamectin benzoate , trichlorphon, chlorpyrifos to P. xylostella larvae, which resulted in LD₅₀ ratio of 0．2093, 0．3446, 0．4833, 0．5245, 0．5964, respectively, compared with those before treatment. However, the oil reduced the toxicity of methomyl, which resulted in LD₅₀ ratio of 2．1420． 鈽匘ropping bioassay showed that C. ambrosioides essential oil could significantly enhance the susceptibility of P xylostella larvae to trichlorphon. fipronil, chlorpyrifos, emamectin benzoate. The susceptibility of P. xylostella larvae to them didn't increase with increased concentration of C. ambrosioides essential oil.鈽匓iochemistry analysis showed that C. ambrosioides essential oil could enhance the inhibition of trichlorphon and chlorpyrifos to AChE and CarE activities of P. xylostella larvae, but have no significant influence on fiproniland emamectin benzoate.鈽匔. ambrosioides essential oil, treated previously, could enhance the susceptibility of AChE to trichlorphon , chlorpyrifos , CarE to enhance chlorpyrifos , GSTs to trichlorphon, fiproni, chlorpyrifos, emamectin benzoate, but have no significant influence on the susceptibility of AChE and CarE to fiproni, emamectin benzoate, trichlorphon.鈽匰canning electron microscopy showed that afer treating with C. ambrosioides essential oil, the distribution of protuberance in the cuticula became impact. The protuberances were wounded and became rugate, but the basal part became smooth.鈽匞C-MS analysis showed C. ambrosioides ensential oil could promote trichlorphon銆?fiproni銆乧hlorpyrifos penetrating P. xylostella larvae skin, which could promote fiproni dose penetrating into skin best.