Assessing the potential economic benefits of classical biological control of the invasive fruit fly Bactrocera dorsalis by Fopius arisanus in Kenya

Abstract

This study proposed a spatially explicit non-linear function for estimating the benefits following the release and establishment of the koinobiont endoparasitoid, Fopius arisanus at a landscape scale in Kenya to control the oriental fruit fly, Bactrocera dorsalis. The proposed model relates the bioecology of the parasitoid to its impacts on fruit growers’ economic benefits per fruit farm. In addition, we used financial information attributed to the cost of importation, conducting associated research, and the release of F. arisanus to estimate the return on investment from the parasitoid’s release in Kenya. We observed distinct variations in potential annual benefits across the diverse mango cultivation regions throughout Kenya. In Kenya, the potential benefits range from negligible benefit to high benefit per acre (US$201- US$255) annually when classical biological control is applied. Furthermore, the cost-benefit ratio analysis showed that in Kenya, for every US$1 invested, the return benefit was US$33.92. In addition in Kenya, the investment yielded a significant net present value of US$13.7 million over a 16-year period and an attractive internal rate of return of 73% compared to the reference discount rate of 12%. The study suggests the need to facilitate further release of the parasitoid (F. arisanus) across major fruit production regions of countries affected by the invasive fruit fly (B. dorsalis).