Influence of seasonal and climatic variables on coffee berry borer (Hypothenemus hampei Ferrari) flight activity in Hawaii

Authors: Johnson, Melissa; Manoukis, Nicholas

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2021
Publication Date: 12/20/2021
Citation: Johnson, M.A., Manoukis, N. 2021. Influence of seasonal and climatic variables on coffee berry borer (Hypothenemus hampei Ferrari) flight activity in Hawaii. PLoS ONE. 16(12). Article e0257861. https://doi.org/10.1371/journal.pone.0257861.
DOI: https://doi.org/10.1371/journal.pone.0257861

Interpretive Summary: Determining the seasonal phenology and abiotic factors involved in flight activity is a critical step in developing an integrated pest management plan for invasive insects. In the present study we examined 14 commercial coffee farms on Hawaii Island to elucidate seasonal flight patterns and the influence of five weather variables on coffee berry borer (CBB) flight. We observed two major flight events that were consistent across all three years: an initial emergence from January-April that coincides with early fruit development and a secondary flight that occurs during the harvest season from September-December. We also found that despite not having a species-specific lure, trap specificity was generally high with CBB making up 81-93% of the total trap catch across all farms. Mean daily air temperature was observed to be the single weather variable with the strongest (positive) relationship to CBB flight activity across all sites. We also found a positive significant relationship between CBB flight and mean daily solar radiation, and a significant negative effect of maximum daily relative humidity above ~94%. Flight activity increased at wind speeds up to ~2.5 m/s and then decreased at speeds above that value. Cumulative rainfall had a positive effect on CBB flight up to a point; flight appeared to be inhibited during periods of heavy rainfall (>100 mm). Our investigation into CBB seasonal phenology and the influence of weather on CBB flight activity revealed important insights that will be useful for the development of future flight prediction models.

Technical Abstract: Coffee berry borer (CBB, Hypothenemus hampei Ferrari) is the most serious insect pest of coffee worldwide, yet little is known about its seasonal flight behavior or the effect that weather variables have on its activity. We sampled flying female CBB adults bi-weekly over a three-year period using red funnel traps baited with an alcohol lure at 14 commercial coffee farms on Hawaii Island to characterize seasonal phenology and the influence of five weather variables on flight activity. We captured almost 5 million Scolytid beetles during the sampling period, with 81-93% of the trap catch comprised of CBB. Of the captured non-target beetles, the majority were tropical nut borer, black twig borer and a species of Cryphalus. Two major flight events were consistent across all three years: an initial emergence from Jan-Apr that coincided with early fruit development and a second flight during the harvest season from Sep-Dec. A linear regression showed a moderate but significant negative relationship between elevation and total trap catch. A generalized additive mixed model (GAMM) revealed that mean daily air temperature has the most significant positive effect on CBB flight, with most flight events occurring between 20-26 °C. Mean daily solar radiation also had a significant positive effect, while maximum daily relative humidity negatively influenced flight at values above ~94%. Flight was positively influenced by maximum daily wind speeds up to ~2.5 m/s and cumulative rainfall up to 100 mm, after which activity declined. Our findings provide important insight into CBB flight patterns across a highly variable landscape and will serve as a starting point for the development of flight prediction models.