Author(s):

Rukesh Pramod KN, MF Acharya and Nilesh Sharadarao Rode

Abstract: Liriomyza trifolii is an important pest of vegetable crops in many parts of the world including India. In this study potted tomato plants were sprayed with recommended field rates of nine insecticides. To assess the persistent toxicity of these insecticides, the plants were infested with L. trifolii adults at 2hr, 1, 3, 5, 10, 12, 14, 16, etc days up to the no mortality observed after insecticidal treatments. The adults were allowed to stay on treated plants for eight hours. The treated plants were kept in a cage covered with muslin cloth. Number of larval mines on leaves, as well as pupation and adult eclosion rates were assessed. Two-way ANOVA procedure of SAS was used for statistical analysis. The nine selected insecticides were tested for their residual effects against this pest. All the insecticides under test gave complete control up to 7 days and then the effect was decreased with increase of time. However, spinosad 0.009 per cent, chlorotraniliprole 0.006 per cent and ethion + cypermethrin 0.045 per cent showed longer persistence up to 16 days had no effect on the number of larval mines, but, pupation was severely hampered and adult eclosion was completely ceased even in treatments with five weeks old residues. Determining the residual activity of insecticides used for controlling this pest is useful in avoiding unnecessary treatments.

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