Sensitivity of Cotesia plutellae and Diadegma semiclausum, parasitoid of diamondback moth (Plutella xylostella L.) to several insecticides
1993
Rejesus, B.M. | Obra, J.B. (Philippines Univ., Los Banos, College, Laguna (Philippines). Dept. of Entomology)
The toxicity of several insecticides (deltamethrin, fenvalerate, teflubenzuron, malathion, methamidophos, carbaryl, cartap, and Bacillus thuringiensis var Kurstaki) to adult Cotesia plutellae and Diadegma semiclausum were determined by residual film method. Based on LC50 and LC95, methamidophos, malathion, cartap, and deltamethrin were toxic to Cotesia while fenvalerate, carbaryl, teflubenzuron, and Bacillus thuringiensis Kurstaki were relatively non-toxic to the parasitoid. Diadegma was most susceptible to methamidophos, cartap, fenvalerate, and deltamethrin. In contrast, carbaryl was non-toxic to this parasitoid. The effect of teflubenzuron, B. thuringiensis Kurstaki and cartap on the parasitization and development of Cotesia and Diadegma was determined by spraying the cabbage plant using the LC50 of DBM to the insecticides with two methods of exposure: 1) one day old parasitized second instar larvae of DBM was sprayed with insecticide and 2) the larvae were sprayed first before they were exposed for parasitization. The first method showed that cartap has the least effect with 67.7% parasitization compared to 75% in the control while teflubenzuron and B. thuringiensis Kurstaki reduced survival to 49 and 45.6%, respectively. The second method showed a reduction in parasitization ranging from 59% to 88% especially with B. thuringiensis and cartap
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