Impact of insecticides on spiralling whitefly, Aleurodicus dispersus (Hemiptera: Aleyrodidae) and its natural enemy complex in cassava under open field conditions

Although insecticides can be used to control pests on cassava (Manihot esculenta Crantz.) they could have detrimental effects on natural enemies. Nine important insecticides, thiamethoxam, imidacloprid, buprofezin, acetamiprid, spiromesifen, triazophos, acephate, thiodicarb and thiacloprid, were selected to test their efficacy against spiralling whitefly, Aleurodicus dispersus (Hemiptera: Aleyrodidae) to clarify selectivity of these insecticides on its natural enemies. All insecticides caused substantial reduction in spiralling whitefly populations on cassava during two seasons. Acephate and triazophos were effective in controlling the spiralling whitefly population (>90% reduction in both seasons) on cassava and recorded higher tuber yield than other insecticidal treatments during both the seasons. All insecticides significantly reduced the emergence of parasitoids (Encarsia guadeloupae Viggiani and Encarsia meritoria Gahan) and percent parasitism (<1%) when compared with the control. However, buprofezin was relatively less toxic to Cybocephalus spp. and Mallada astur (Banks) than other insecticides. To summarize, buprofezin can be included in Integrated Pest Management (IPM) programs since it was comparatively effective in controlling of A. dispersus (>75% reduction in both seasons) and relatively less toxic to Cybocephalus spp. and M. astur which are the major predators of spiralling whitefly in cassava.