Field evaluation of glutathione and glutamicacid as host marking pheromones for controlof Tephritid fruitflies in a mango orchard inKenya

Abstract

BACKGROUND: Tephritid fruitflies are a major constraint to the global production of horticultural crops. In Africa, an array ofnative and alien invasive fruitfly species represents a key challenge to the horticultural industry. In an effort to develop a safermanagement tool for these pests, we previously identified glutathione (GSH) and glutamic acid (GA), as the host marking pher-omones (HMPs) ofCeratitis cosyraandCeratitis rosa, respectively. Here, we report on the effectiveness of these compounds(GSH and GA) in reducing natural fruitfly population infestations in mango orchards. Mango trees at two different agroecolog-ical zones in Kenya were sprayed with HMPs, and the fruits sampled periodically and assessed for fruitfly emergence. Fruitflyemergence data were compared to two controls, the positive control using spot spraying of food bait (SS), and the negativecontrol using water (W).RESULTS: The two HMPs and SS substantially decreased fruitfly emergence from the sampled mangoes. GSH and GA treatedmangoes showed reducedC. cosyraandC. rosainfestation by∼70–75% relative to control (W), and with variation noted inthe pheromone applied and the recovered fruitfly species. The adult emergence in pheromone-treated plants compared favor-ably with the positive control SS. However, the HMPs had little impact on reducingBactrocera dorsalisinfestation of mangoes.CONCLUSION: The decrease in fruitfly emergence in sampled mango fruits from HMP treated trees corroborate previous labo-ratory results and support the prospect of using HMPs in the management of African fruitfly species.