Evaluation of Synthetic Insecticides for the Management of Sweet Potato Weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae)

Vinod Anjali, Jayaprakas C. A.


Sweet potato weevil (SPW), Cylas formicarius (Fab.) is the most devastating pest of sweet potato in the field and tubers under storage. The infestation of weevil reduces the quality of the tubers; therefore, it affects marketability and economic value of the crop as well. Efficacy of six insecticides, namely Imidacloprid, Chlorpyrifos, Malathion, Dimethoate, Dichlorvos and Quinalphos at three concentrations (0.001, 0.01 and 0.05%) were evaluated against SPW by two different bioassay methods - foliar application and vine dipping- and compared their toxicity against control with water. In the case of foliar application, the mortality of SPW on 1, 3, 5, 7 and 9 days after treatment (DAT) was highest in the treatments with Imidacloprid and Chlorpyrifos. In contrast, it was least in Malathion and Dimethoate. Imidacloprid was found most effective for vine dipping, and its effect lasted upto 9 DAT. The present study revealed that foliar application of Imidacloprid at the concentrations of 0.01 and 0.05% was most effective against SPW.

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