Evaluation of Persistent Toxicity of Insecticides against Spodoptera litura on Sunflower at Elevated CO₂ and Temperature Conditions

Insecticides with different mode of actions viz., spinosad, emamectin benzoate, thiodicarb, monocrotophos and fenvalerate were applied at LC₅₀ and field recommended concentrations (FRC) to study the persistence of insecticides under elevated CO₂ (550 ± 25 ppm) and temperatures (28, 29, 31, 33 and 35ºC). These insecticides often caused significantly higher mortalities at 28ºC than at 35ºC. The mean per cent corrected mortality, persistence in days and persistent toxicity values decreased for all insecticides with increase in temperatures at both levels of CO₂ and corresponding temperatures. Among the five insecticides, emamectin benzoate (13 days) and spinosad (12 days) persisted for longer periods with highest mean per cent corrected mortality (58.1 and 56.3) with PT values of 749.5 and 675.0, respectively. The next in order were thiodicarb, monocrotophos and fenvalerate.