Effect of sublethal concentrations of insecticides on the larval and pupal duration of S. litura under eCO2 and eTemp conditions

Experiment was conducted to study the effect of eCO2 and eTemp on the on the larval and pupal developmental periods of S. litura after exposed to sublethal concentrations of insecticide viz., spinosad, emamectin benzoate, thiodicarb and monocrotophos. Among these insecticides emamectin, thiodicarb and monocrotophos was positively related with temperature and proved effective at higher temperatures, whereas spinosad was negatively related with temperature. The test insecticides prolonged the larval and pupal durations with increase in sublethal concentrations. But in contrats with increase in temperature from 28 to 35 ºC under both aCO2 (380 ± 25 ppm) and eCO2 (550 ± 25 ppm), the larval and pupal durations were decreased significantly. Negatively correlated with temperatures exhibited reduced efficacy at higher temperatures which results in higher lethal concentrations, this might be reason for prolonged larval durations at higher temperatures.