Effectiveness of insecticides of synthetic, plant and animal origin against the mango stone weevil, Sternochetus mangiferae (Fabricius) (Coleoptera: Curculionidae)

Mango stone weevil (MSW), Sternochetus mangiferae Fabricius, is a widely distributed monophagous pest of mango. Assessment of the potential of non-pesticidal controls has indicated few alternatives to the use of insecticide sprays for control. Field studies were conducted over 3 years to evaluate the efficacy of selected synthetic, botanical and animal-origin insecticides in reducing MSW infestation in Alphonso mango. It was found that four synthetic insecticides-deltamethrin, acephate, carbaryl and ethofenprox-obtained levels of infestation of between 3.3% and 14.8% at harvest, in contrast with a level without control of 33.0%. Two biological-origin insecticides-azadirachtin (of plant origin) and fish oil rosin soap (of animal origin)-obtained intermediate levels of control, of 27.4 and 23.0% respectively, which were not significantly superior to no-treatment. In order to assess the reliability of pre-harvest evaluations, to address the risk of harvest data being lost, information was also gathered of infestation of mangoes in early and late seasons prior to harvest. Although the rank-ordering of controls in their performance varied between early season, late-season and harvest assessments, the pre-harvest assessments reflected the superior control by synthetic insecticides to that by agents of natural origin.