Postharvest population reservoirs of Coffee Berry Borer (Coleoptera: Curculionidae) on Hawai‘i Island

Authors: JOHNSON, MELISSA - Orise Fellow; FORTNA, SAMUEL - University Of Hawaii; HOLLINGSWORTH, ROBERT - Retired ARS Employee; Manoukis, Nicholas

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/2019
Publication Date: 8/2/2019
Citation: Johnson, M.A., Fortna, S., Hollingsworth, R., Manoukis, N. 2019. Postharvest population reservoirs of Coffee Berry Borer (Coleoptera: Curculionidae) on Hawai‘i Island. Journal of Economic Entomology. 112(6):2833-2841. https://doi.org/10.1093/jee/toz219.
DOI: https://doi.org/10.1093/jee/toz219

Interpretive Summary: Coffee Berry Borer (CBB) is the most serious insect pest of coffee globally, and a relatively new problem in Hawaii. CBB spends almost its entire life cycle in coffee fruit, forming galleries in the seed, which makes it difficult to control. In this study we investigated which dry coffee berries (“raisins”) in the inter-crop season contain most of the CBB: those remaining on trees after harvest, or berries that fell to the ground. We found that for the farms we studied raisins on trees contained more CBB than those on the ground, but these were less numerous, leading to a roughly even load of CBB between raisins in the two places. Furthermore, the berries on the ground with higher numbers of CBB were those in the drip line (right under trees) compared to the center aisle. From this study we conclude that post-harvest sanitation (removal of unharvested berries) is critical, that it should focus on trees, but that eliminating CBB from fallen berries in the drip line is an important area for improving control.

Technical Abstract: Coffee Berry Borer (Hypothenumus hampei Ferrari, CBB) is the most damaging insect pest of coffee worldwide. Sanitation of coffee farms, including the removal of coffee berries remaining on the trees and ground after the main harvest, is an important aspect of Integrated Pest Management (IPM) programs for this invasive beetle. While old coffee berries (raisins) are widely acknowledged as a reservoir for CBB between seasons, few studies to date have attemped to quantify adult populations in raisins remaining on farms post-harvest. We collected ground and tree raisins at six commercial coffee farms on Hawai‘i Island from February-June 2017 to assess raisins as population reservoirs of CBB during the transition period between seasons. We estimated raisin density, raisin infestation, and the number of adult CBB per raisin in three distinct areas across all farms: trees, drip lines (ground below the tree foliage), and center aisles (ground between tree rows). We also assessed infestation of the new season’s crop by conducting whole-tree counts of infested green berries on each farm. Of the total number of raisins collected across the sampling period on all farms, 90% were from the ground. The mean number of raisins per m2 across all sites/sampling dates was significantly higher in the dripline compared to the center aisle and trees (131 vs. 17 and 12 raisins, respectively). The mean percentage of infested raisins was significantly higher in the trees (70%) relative to both areas of the ground (dripline = 22%, center aisle = 18%). The mean number of adult CBB per infested raisin was significantly higher in trees compared to the dripline and center aisle (12.64 vs. 3.21 and 2.15 adults, respectively). Mean adult mortality was significantly higher in the dripline (63%) and center aisle (71%) compared to the trees (12%). Although infestation was significantly higher in the trees, the high density of raisins on the ground resulted in five out of six farms having the largest CBB population in ground raisins. Lastly, we found a significant positive correlation between infestation of ground and tree raisins and infestation of the new season’s crop (r2 = 0.58). Our findings confirm the importance of sanitation in CBB management and demonstrate the negative impact that poor post-harvest sanitation can have on the following season’s crop.