Bioactivities And Mechanism Of Praxelis Clematidea Essential Oil Against Diamondback Moth (DBM), Plutella Xylostella

Praxelis clematidea originates from South America. In China, the weed was found in Hong Kong in 80s of 20th century and was widely distributed in South China. Later, it became one of dangerous and destructive alien weed.In this paper, the effect of Praxelis clematidea essential oil on the toxicity, antecedence, activity of carboxyl esterase (CarE) and glutathione S transferase (GSTs), respiratory rhythm as well as olfactory response of Diamondback moth (DBM), Plutella xylostella were investigated. In addition, synergism of the essential oil to averment and chlorpyrifos were studied. And chemical constituents of the essential oil were examed based on the GC-MS.The result showed that LC50 of Praxelis clematidea essential oil against DBM larvae with topical application 48 h was 21.0215×104 mg/L, and with fumigation treatment 48 h was 14.0413×104 mg/L.Antifeedant bioassay showed that AFC50 of the essential oil against DBM larvae was 2.6863×104 mg/L. The antifeedant rate could reach 100% when the treating concentration was 10×104 mg/L .There were no significant difference in antifeedance at different treating time.Respiration of DBM larvae treated with Praxelis clematidea essential oil was significantly influenced but didn't show irregular fluctuation type. The essential oil also showed repellent activity to DBM adult. The selectivity to distiller wate(r58.74%) was significantly higher than that to the essential oil(31.86%).The activities of CarE and GSTs of DBM larvae treated with Praxelis clematidea essential oil changed but not irregularly influenced.When the proportion of Praxelis clematidea essential oil and avermectin was 1:1, the co-toxicity coefficient was highest at 290.3168. However, the increasing was showed withthe proportion 3:1 for the co-toxity efficient was 140.9777. when the toxity concentration reached 1000 mg/L,the effect of Praxelis clematidea essential oil against DBM larvae for (1d,3d, 7d) on potted plants was 23.68%,31.57% and 33.50%t,respectively.GC-MS analysis indicated that Praxelis clematidea essential oil have 37 chemical constituents, in which elemene, junipene, bicyclo[4.4.0]dec-1-ene,2-isopropyl-5-methyl-9-methylene-, ( +OR- )-.BETA.-ACORENOL and cadinol are main constituents and the relative content are 10.046%, 12.065%, 18.214%, 14.165% and 10.476%, respectively.