Coffee berry borer (Coleoptera: Scolytidae) population dynamics across Hawaii Island’s diverse coffee-growing landscape: optimizing location-specific pesticide applications

Authors: Johnson, Melissa; Manoukis, Nicholas

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2024
Publication Date: 4/5/2024
Citation: Johnson, M.A., Manoukis, N. 2024. Coffee berry borer (Coleoptera: Scolytidae) population dynamics across Hawaii Island’s diverse coffee-growing landscape: optimizing location-specific pesticide applications. Journal of Economic Entomology. https://doi.org/10.1093/jee/toae061.
DOI: https://doi.org/10.1093/jee/toae061

Interpretive Summary: To develop successful area-wide IPM programs, it is critical to understand how coffee berry borer (CBB) populations persist and disperse across the landscape. In the present study, we characterized CBB flight activity, fruit phenology and infestation, CBB position within the fruit, weather, and management practices across a broad elevational gradient in the two major coffee-growing districts of Hawaii Island. We analyzed these data to determine if IPM recommendations should be updated based on location-specific differences in CBB population dynamics that are driven by weather, plant phenology, and management practices. We observed significantly larger populations of CBB in Kona compared to Ka’u based on bi-weekly trap catches. Larger CBB populations were also observed at low elevations compared to mid and high elevations. Using information on CBB flight and coffee plant phenology, we suggest that sprays could be reduced by 42-67% for low-elevation farms, 56-78% for mid-elevation farms, and 67-92% for high-elevation farms when compared with recommendations from the current IPM. Our data also provides growers with a better understanding of when sprays should occur during the season to maximize benefits based on peak CBB flight times (i.e., exposure to pesticides) and availability of fruit.

Technical Abstract: A major challenge to area-wide management of coffee berry borer (Hypothenemus hampei Ferrari) (Coleoptera: Scolytidae) is understanding how a heterogeneous coffee-growing landscape affects coffee berry borer population dynamics across temporal and spatial scales. We examined coffee phenology, weather, coffee berry borer flight activity, infestation, coffee berry borer position within the fruit, and management across 14 commercial coffee farms from 2016 to 2018 on Hawaii Island to characterize variation among districts and elevations. Here we aim to determine whether the timing of pesticide applications might be optimized based on specific locations. We observed larger populations of coffee berry borer at low-elevation farms and in the Kona district compared to mid- and high-elevation farms and the Ka’u district. Temperature, relative humidity, and rainfall all differed significantly across districts and elevations. We also observed a trend of higher fruit production at low-elevation farms compared to high-elevation farms, and differences in the timing of fruit development. Infestation increased with higher pest pressure and air temperatures and reduced fruit availability early and late in the season. Lastly, the timing and number of management interventions varied among districts and elevations. Combining information on trap catch, infestation, coffee berry borer position, and plant phenology, we present an optimized pesticide spray schedule for each location and find that the number of sprays could be reduced by 33–75% in comparison to the existing integrated pest management recommendations while maintaining effective control. Implementing a coordinated area-wide approach refined by small-scale optimization will lead to improved management of coffee berry borer on individual farms and a reduction in pest pressure across the coffee-growing landscape.