Department of Entomology, Punjab Agricultural University, Ludhiana
1Part of the Ph.D. dissertation of the senior author submitted to the Punjab Agricultural Uaiversity, Ludhiana
The influence of monsoon and post-monsoon seasons on the persistent toxicity of seven insecticides in LVC and the EC/WP formulations was tested against jassid Amrasca biguttula biguttula (Ishida) on cotton. The LVC and the WP formulations of insecticides in general give significantly greater persistent toxicity in the monsoon season than in the post-monsoon season even with comparatively low spray deposits. On the other hand, EC formulation gave significantly more persistent toxicity in the post-monsoon season than in the monsoon season. The persistent toxicities of individual insecticides based on PT values also increased in the LVC and the WP formulations and deceased in the EC formulation in the monsoon season as compared with the post-monsoon season except in a few cases: Among the insecticidal formulations, the LVC formulation was significantly more persistent than the EC/WP formulations in both the seasons inspite of its comparatively low spray deposits in different insecticides than of the EC/WP formulations. However, the differences were more evident in the monsoon season than in the post-monsoon season.
