Potential of Oecophylla longinoda Latreille (Hymenoptera: Formicidae) in managing major insect pests in organic cashew production systems

Cashew production in Tanzania is severely constrained by sucking insect pests such as the coreid coconut bugs (Pseudotheraptus wayi Brown), the mirid bugs, Helopeltis spp. and thrips spp. These pests damage flushing foliar and floral shoots as well as young cashew fruits and nuts. Farmers rely heavily on insecticides in controlling these pests and there are no suitable alternative control methods compatible with organic cashew production. Weaver ants, Oecophylla longinoda Latreille have for long been considered as effective biological control agents against sap-sucking pests of cashew, but studies on their effectiveness as compared to conventional insecticides had never been conducted. The current study evaluated the efficiency of O. longinoda as compared to the recommended conventional insecticide, lambda cyhalothrin (Karate®) in controlling major cashew insect pests and compared the resulting cashew yield. The damage caused by each pest was significantly lower (P 0.05) in the damage between O. longinoda and Karate® treated trees suggesting that the two treatments are equally effective. The difference in the damage levels was directly reflected in the mean cashew yield. The two season’s results showed an average yield increases of 58.2 and 60.7 % in the insecticide-treated and in the O. longinoda-protected trees, respectively, in relation to untreated control plots. Thus, O. longinoda can serve as an alternative to chemical insecticides in Tanzanian cashew protection.