Influence of temperature on spinosad toxicity in different populations of Plutella xylostella (Linnaeus)

Diamond back moth, Plutella xylostella (Linnaeus) is one of the major insect-pest of cole crops, causing high yield losses. In present study, larval populations of P. xylostella, collected from different regions of Punjab i.e. Amritsar, Kapurthala, Malerkotla and Ludhiana were exposed to different concentrations of spinosad at 15, 20, 25 and 30 degrees C for evaluation of LC50 values. The LC50 (Lethal concentration) increased from lower (15 degrees C) to higher (30 degrees C) temperature for all populations of P. xylostella. Negative correlation was observed between the temperature coefficient and toxicity of spinosad towards P. xylostella populations, which decreased with increase in temperature. The LC50 values varied among different populations of P. xylostella i.e. Amritsar populations with higher LC50 values followed by Kapurthala, Malerkotla and Ludhiana populations. The temperature and insecticide exposure history both affected the toxicity of spinosad for P. xylostella. The information would be helpful in developing management strategies for P. xylostella according to prevailing environment conditions.