insects

How do bumble bees use landscapes throughout their life cycle?

Bumble bees are some of the world’s most important pollinators, yet many bumble bee species are in decline.  Our understanding of how landscape changes affect bumble bees is often limited to studies of where they forage on flowers.  Through this project, REU students will test how bumble bees use landscapes throughout their life cycles. Students will compare the behavior and abundance of bumble bees across habitat types. We hypothesize that bees use different habitat types for nesting vs.

Predation on pollinators in urban gardens

Urban flower gardens are growing in popularity, and have the potential to contribute significantly to pollinator habitat.  However, it is unknown whether these gardens provide a safe haven for declining populations or create low quality habitat that contributes little to conservation. Monarch butterflies are abundant in urban gardens in the San Francisco Bay Area. One concern is that monarch caterpillars in cities experience increased risk of predation by human-associated animals such as paper wasps and yellow jackets.

Human influences on bee pollinators

Bee pollinators are critically important for agricultural and natural ecosystems. Together, wild and managed bee species contribute to the pollination of 80 crops with an estimated annual value of >$200 billion globally, >$29 billion for US agriculture, and >$9 billion for California.

Ecological interactions in managed systems

Anthropogenic effects, notably, habitat conversion from natural to managed systems, can alter interactions between plants, insects, and microbial communities; but these effects on such complex systems are poorly understood. Bacteria and yeast that live in floral nectar affect pollinator visitation and influence floral characteristics.

Thermal stress on monarch butterfly caterpillars

Ongoing climate change will continue to increase the frequency and intensity of extreme climate events, such as heat waves and droughts, with potentially wide-ranging consequences for species interactions. Temperature and moisture availability strongly affect the development of both monarch butterflies and their milkweed host plants, but the role of extreme climate events is less well characterized.

Two plausible hypotheses in the monarch-milkweed system center on heat waves: