Economic impact of a classical biological control program: application to Diachasmimorpha longicaudata against Bactrocera dorsalis fruit fly in Kenya

Classical biological control (CBC) has been exploited as a safer alternative for suppressing the oriental fruit fly, Bactrocera dorsalis, by importing, rearing, and releasing the larval parasitoid, Diachasmimorpha longicaudata . Although D. longicaudata has been released in Kenya through the Africa Fruit Fly Programme, the extent of its dispersal and subsequent economic benefits have not yet been established. This paper models the spatio-temporal dispersal of the parasitoid using the fuzzy cellular automata approaches and estimates the net benefit from each dollar invested in the CBC approach. We calculated the return on investment based on funding into the programme between 2006 and 2015 and the result of the dispersal range of the parasitoid predicted using an artificial intelligence algorithm. The investment yielded a significant net present value of US$42.8 million over the 16 years. Besides, the cost–benefit ratio showed that for every US$1 invested, the return benefit was US$93 , confirming the profitability of the CBC program. The economic gains are significant considering that there is no environmental contamination and possible adverse effects from the CBC intervention. The study findings support investment in biological control strategies for the eco-friendly and area-wide management of B. dorsalis.