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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » Research » Publications at this Location » Publication #429110
Research Project: Development of New and Improved Surveillance, Detection, Control, and Management Technologies for Fruit Flies and Invasive Pests of Tropical and Subtropical Crops

Location: Tropical Crop and Commodity Protection Research

Title: Environmental filtering drives patterns of ant species richness and activity across Hawaiian coffee farms

Author
item COWAL, SANYA - University Of California Santa Cruz
item MUELLER, MATTHEW - Hilo High School
item Johnson, Melissa

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2026
Publication Date: 2/21/2026
Citation: Cowal, S., Mueller, M., Johnson, M.A. 2026. Environmental filtering drives patterns of ant species richness and activity across Hawaiian coffee farms. Journal of Insect Science. 26(1). https://doi.org/10.1093/jisesa/ieag007.
DOI: https://doi.org/10.1093/jisesa/ieag007

Interpretive Summary: In the present study we conducted observational surveys of arboreal ants on 15 coffee farms across a 600-m elevational gradient on Hawaii Island to describe patterns of ant species richness and abundance across the highly variable landscape. We found that ant species richness and abundance in Hawaiian coffee agroecosystems are largely driven by environmental factors including elevation, rainfall, temperature, and humidity. We also found that Kona had higher richness and abundance relative to Ka'u, likely reflecting differences in microclimate, vegetation complexity and management. Lastly, the five most common ant species had no negative effects on overall richness, suggesting that competitive exclusion is not a driving factor in determining ant community assembly in these agricultural settings. Our results lay the foundation for future research to investigate the ecological roles of various ant species in Hawaiian coffee.

Technical Abstract: Ants may function as pests or beneficial insects in agricultural systems, serving a variety of ecological roles including scavengers, predators, seed dispersers and pollinators. In Hawaii, all ant species are non-native, offering a unique opportunity to determine the influence of various factors in shaping invasive ant communities. We conducted ant surveys on 15 coffee farms across a 600-m elevational gradient (200-800 m a.s.l.) on Hawai’i Island in the Kona and Ka’u coffee districts in 2017 and 2018. We investigated the effect of elevation, temperature, rainfall, humidity, and coffee-growing district on ant species richness and abundance. In addition, we assessed the influence of common species on overall ant richness. We identified a total of 22 ant species across three subfamilies, with Brachymyrmex obscurior, Ochetellus glaber, Pheidole megacephala, Plagiolepis alluaudi and Tapinoma melanocephalum being the most common species. Both ant richness and abundance decreased with increasing rainfall and elevation. Abundance increased with temperature, and richness increased with humidity. Kona farms exhibited greater richness and abundance than Ka’u farms, likely reflecting warmer and drier conditions and higher on-farm vegetation complexity in the Kona district. The most common species did not reduce overall species richness, and in some cases were associated with higher richness. Our results provide novel baseline information on ant communities in Hawaiian coffee and can be used to inform future studies investigating the role of ants in these unique agroecosystems.