Investigating the Climatic Factors that Influence the Activity of the Long Horned Bee Melissodes tepida timberlakei.

Native solitary bees are pollinators that help maintain the health and biodiversity of California’s native plant communities. However, there is limited research on how their behavior responds to daily weather variability. Solitary bees differ from eusocial species in that they have a short seasonal activity period, typically 1-2 months, during which they must complete foraging and nest provisioning. This period can be disrupted by unfavorable weather, reducing foraging opportunities and reproductive output. This study used the solitary ground-nesting bee, Melissodes tepida timberlakei, as a model to assess responses to daily weather variation. M. tepida is active from mid-May to early July. Climatic variables, including ground temperature, ambient temperature, humidity, and cloud cover, were tested to determine their influence on foraging activity.Field observations were conducted over 10 days at the UC Santa Barbara Campus Lagoon, recording bee nest emergence times as a proxy for activity. Ground temperature was measured on-site while other weather data were sourced from the Muni Santa Barbara weather station via Iowa State University’s ASOS Network. Data analysis involved the use of linear-mixed effects modeling, which identified ground temperature and cloud cover as the strongest predictors of bee activity. These findings highlight how daily weather conditions influence M. tepida’s activity and provide insight into how native bees may be impacted by global change. This poster was presented at the UCSB Center for Science and Engineering Partnerships (CSEP) 2025 Research Colloquium.