Varying effects of two lots of the botanical insecticide Neemix®4.5 on immature survival and adult oviposition behavior of the diamondback moth,Plutella xylostella(Lepidoptera: Plutellidae)

Variability in the insecticidal effects of botanical preparations has been one of the major obstacles in the application of this type of insecticide. Understanding of the variability may help to improve formulations of the preparations and develop more practical strategies for field applications. Here we report the varying effects of two lots of the same commercial neem formulation, Neemix® 4.5, on the diamondback moth, Plutella xylostella L. We found that one lot had stronger adverse effect on the development and survival of P. xylostella larvae but little repellent effect on the adults, whereas, the other lot had a weaker effect on the larvae but a substantial repellent effect on the adults.