Economic Rationale of Using African Weaver Ants, Oecophylla longinoda Latreille (Hymenoptera: Formicidae) for Sustainable Management of Cashew Pests in Tanzania

Abstract

Cashew nut, Anacardium occidentale Linnaeus, is an important crop to the African economy, contributing to livelihood of many families. It is among the top foreign-currency-earning crops in East and West African countries. The crop is attacked by several sucking pests that survive on multiple host plants. These include: Pseudotheraptus wayi, Helopeltis anacardii, H. schoutedeni, and Selenothrips rubrocinctus. Management of these pests is usually a challenge which triggers irrational use of synthetic pesticides. Excessive use of pesticides concerns human health and pollution in the environment. The use of African weaver ants, Oecophylla longinoda, has presented an alternative to pesticides for sustainable cashew pest management. The predator was found to be as highly effective (P < 0.0001) as the recommended insecticide (Lambda cyhalothrin) (P < 0.0001) in controlling cashew pests. The several economic analyses on the profitability of the technology over the recommended pesticides by partial budgeting, marginal rate of returns, benefit-cost ratio and net present value proved O. longionda to be superior to pesticides. The partial budgeting indicated a net benefit of US$7.72 per cashew tree by changing from insecticides to O. longinoda within two seasons. The dominance analysis for marginal rate of returns indicated a net profit of US$11.39 per tree in two seasons compared to US$5.74 per tree gained from Lambda cyhalothrin. If adopted for use, the predator will provide a sustainable solution to cashew pest management and overcome the pesticide residue threats in marketed cashew from Africa.