Why the Squash Bee Is Important

Jun 2, 2014

Peponapis pruinosa isn't your common household word.

But among the people who study pollinators, it is.

Also known as a squash bee, it is an important pollinator of cultivated crops of squash, pumpkins, and others members of the genus Cucurbita.

Enter Katharina Ullmann, a graduate student in the Neal Williams lab in the Department of Entomology and Nematology at the University of California, Davis.

She researches them, studying their persistence in agricultural landscapes.

And on Wednesday, June 4, Ullmann will present a seminar on her research: "Squash Bee Persistence in Agricultural Landscapes: the Role of Connectivity and Disturbance" from 12:10 to 1 p.m. in 122 Briggs Hall, located off Kleiber Hall Drive. This is the last in the series of spring seminars hosted by the department.

"It is well documented that wild native bees can benefit many crops through increased seed and fruit set, thus providing sustainable pollination alternatives in cases of honey bee decline and increased honey bee rental prices," Ullmann says.  "Yet, it is unclear how to best manage crop systems to support wild native bees. Research on enhancing wild native bees has historically focused on field border management. However, to ensure the sustainability of a crop-pollination system, a comprehensive approach should also include within field practices."

"Promoting a whole-farm pollinator management strategy is especially important given that agricultural intensification is associated with practices that negatively impact wild native bees. Whole-farm strategies may provide effective alternatives for growers who are slow to adopt resource-intensive, border-management practices. The proposed project will contribute to our understanding of these strategies by determining the impact of tillage practices and crop rotations on a ground-nesting, native bee that is an important pollinator in a specialty crop system."

Ullmann said that Cucurbita crops (including squash and pumpkin) rely on pollinators to set fruit. "The specialist squash bee, Peponapis pruinosa, is an important pollinator of Cucurbita and can reduce grower reliance on rented honey bee colonies. In-field management is particularly relevant for this species given that it nests preferentially below its host's vines. I will use observational surveys and manipulative experiments to identify crop rotation schemes and tillage practices that benefit P. pruinosa. These results provide insights into how species persist in agricultural landscapes, with an emphasis on the roles of connectivity and disturbance."

Ullmann, who expects to receive her doctorate in entomology in September 2014, researches population persistence in dynamic landscapes, and on-farm beneficial insect habitat enhancements. Her interests also include supporting citizen science, translating research related to pollinator conservation and encouraging dialogue between researchers and farmers.

She developed a native bee YouTube channel aimed at providing a direct line of communication between university researchers, farmers and the general public. In addition, she developed the blog Pollinator Farm and associated social media handles on Twitter and Facebook.

Ullmann's seminar on June 4 is to be video-recorded for later posting on UCTV.