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| Laboratory Toxicity and Field Efficacy of Azadirachtin to Henosepilachna vigintioctopunctata (Fabricius) in Different Instars |
| LI Zhao-fang |
| Department of Resources and Environment,Heze College,Heze 274000,Shandong,China |
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Abstract Testing result in laboratory showed that the toxicity of azadirachtin to Henosepilachna vigintioctopunctata was deducted with the increase of instars.The larva in 1-2 instar was the most sensitive,both of LC50 values were less than 0.2 mg·L-1. LC50 of azadirachtin to the 3-4 instar larva was less than 1.0 mg·L-1.The toxicity to the adult was decreased obviously,it’s LC50 was 2.122 7 mg·L-1 in 24 h.In the field,the effect of azadirachtin against larva was over 91.17 % at the 7th day at 400-800 times,it suggested the insecticide could be applied at 600-800 times in farming practice,the effect of azadirachtin against adult was over 81.20 % at the 7th day at 400-600 times,it suggested the insecticide could be applied at 400-600 times.
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Received: 19 May 2008
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