Options for Managing Antestiopsis thunbergii (Hemiptera: Pentatomidae) and the Relationship of Bug Density to the Occurrence of Potato Taste Defect in Coffee

Abstract

Potato taste defect is a potato-like smell found in green and roasted coffee beans. Potato taste defect reduces the flavor experience of finished coffee and causes it to be rejected by consumers. The presence of potato taste defect has been associated with insect damage, especially damage from the Antestia bug, Antestiopsis thunbergii (Gremlin) (Hemiptera: Pentatomidae). A 2-yr study was conducted to evaluate the effectiveness of integrated pest management using pruning alone or in combination with several commercially available insecticides to control a field population of Antestia bug and to assess the relationship between these treatments and the occurrence of potato taste defect in coffee using laboratory and field tests. Field trials were conducted in 3 major coffee growing regions of Rwanda: Rubona, Gakenke, and Kirehe. In laboratory bioassays, significant differences were found between insecticides on the percentage mortality of adult bugs. The percent mortality was higher for pyrethroid, Fastac (Alpha-cypermethrin), and pyrethrins (Pyrethrum 5EW, Pyrethrum EWC + Sesame and Agroblaster) than for the neonicotinoid, imidacloprid. Mortality from imidacloprid increased over time, providing a lower mortality than Pyrethrum 5EW and Agroblaster 12 h post-treatment. In the field, the highest mean mortality was achieved with Pyrethrum 5EW, Fastac, and Pyrethrum EWC applied to pruned coffee trees. Additionally, pruning alone registered a statistically higher mean insect mortality than unpruned coffee trees without insecticides application. Multiple logistic regression analysis indicated that potato taste defect was positively associated with the bug density and the extent of damage caused by Antestia bug. The study suggests that pruning combined with insecticide application, especially Fastac, provides better control of Antestia bug and significantly reduces potato taste defect compared to either pruning or insecticide application alone.