Red rust thrips in smallholder organic export banana in Latin America and the Caribbean: pathways for control, compatible with organic certification

Abstract

Since 2010, red rust thrips (RRT) have become a serious pest in organic export banana plantations, causing yield losses of 30-40%. Although RRT blemishes on banana peel are only cosmetic, exporters apply zero tolerance. During 2014-2017, FONTAGRO co-financed studies on measures to reduce RRT damage in smallholder organic export banana. Research was initially guided by an IPM approach based on thrips population thresholds and linked abiotic factors, in order to schedule practices. Initial studies resulted in a preventive model for thrips management based on the yearround use of transparent bags with 3-mm orifices to protect bunches just as the bell emerges and before bracts open. This approach minimizes losses due to both Chaetanaphothrips signipennis found in Peru and Ecuador and Chaetanaphothrips orchidii common in the Dominican Republic. Experiments to develop scouting methods and establish thresholds suggested three conclusions: C. signipennnis flies very little, complicating trapping even with pheromones; thresholds for economic damage are very low; and scouting is difficult, costly and not practical for decision making. Routine monitoring of losses caused by RRT and other factors should be done during packing. Experiments to test the effectiveness of bagging and the use of applied products to repel or kill thrips showed that bagging alone reduced losses by 90-100% compared to bunches with no bag. Applications of organic products to the bell at bagging and the leaf whorl and the upper bunch stem simultaneously with other bunch practices reduced losses further by 0-8%. Studies of biological control identified predators, parasitoids and entomopathogens which attack different stages of thrips. Preliminary lab and release studies suggest that biological control should be further developed. However, RRT form part of a complex of insect bunch pests, and the use of general or targeted applications should be reviewed to avoid the use of products which reduce beneficial organisms.