The Control Effect Of Mixture Of Osthol And Emamestin Benzoate On Plutella Xylostella L.

The diamondback moth(DBM),Plutella xylostella(L.),is one of the most destruetive insect pests of cruciferous crops.For the purpose of decreasing resisstance and cut down cost,this paper aims to screen out the best ingredient percentage of osthole and emamestin benzoate and machining them into formulation,in order to control the important vegetable insects of Plutella xylostella(L.) effectively and costly. Thus,this paper has been studied from the following aspects.The toxicity in the lab to Plutella xylostella(L.) larvae was tested with spot and leaf-dipping.When osthole and emamestin benzoate that had high toxicity to Plutella xylostella(L.) 3^nd instar larvae were tested with spot 48 hours later,the LC₅₀ of osthole is 41.2109mg/L,and the LC₅₀ of emamectin benzoate is 0.4544mg/L.The LC₅₀ of osthole is 0.3107mg/L,and the LC₅₀ of emamectin benzoate is 0.2133mg/L with leaf-dipping after 24 hours.The best ingredient percentage was screened with Horsfall toxicity test design and leaf-dipping.The results showed that when the ingredient percentage of ostholeand emamectin benzoate was 60:1,the synergistic effect was the most obvious,and the co-toxicity coefficient was 136.The field controlling trail was carried out with the formulation of 0.3% osthole-emamectin benzoate EC and the antitheses pesticides of 2.0%emamectin benzoate ME and 0.4%osthole EC to Plutella xylostella(L.).The results showed that when the dosage was 500 times,1000 times,2000times in the field,the formulation of 0.3%osthole-emamectin benzoate EC had well controlling effect to Plutella xylostella(Linnaeus),and the controlling effect was 98.45%,96.80%and 91.62%after 10d.There are no harm appearing with persistent effect.Thus,the commendable dosage of 0.3%osthole-emamectin benzoate EC in the field was 2000 times.