COS 120-5 - Horde of the flies: Pollinator composition and trends in Plymouth County, MA

Tuesday, August 16, 2022

4:30 PM – 4:45 PM EDT

Location: 518C

Presenting Author(s)

WW

Wes V. Walsh

Massasoit Community College
Brockton, MA, United States

Coauthor(s)

JP

Jordan Palmer

Research Mentor
Massasoit Community College, United States
BM

Belunda Moise

Massasoit Community College, United States
AG

Adam Germaine

Massasoit Community College, United States
PS

Prisca Sanon

Massasoit Community College, United States
CO

Christina Orazine

Massasoit Community College, United States
AO

Andrew Oguma

Massasoit Community College, United States
MB

Michael Bankson

STEM Coordinator
Massasoit Community College, United States

Background/Question/Methods

Discourse around global pollinator declines typically focuses on the plight of bees. However, when considering plant visitation rates alongside efficiency per visit, non-bee insect pollinators provide pollination services similar to bees. Compared to bees, many non-bee insects have wider flight ranges, rely less on natural habitats, and have larvae not dependent on floral resources, all characteristics which may make non-bee insects respond differently to environmental changes. If their response does vary, non-bee insects could safeguard against potential bee declines caused by habitat changes or, conversely, non-bees might require different conservation efforts. Alternatively, possible bee declines may only be part of a larger insect decline. Determining the prevalence of non-bee pollinators, their response to environmental changes, and overall pollinator trends demands more inclusive research. This study explores the abundance of different pollinator groups on an urban to rural gradient and compares their reactions to natural and anthropogenic factors. Here, subjects were limited to taxa identified as pollinators in most literature: Hymenoptera, Diptera, Lepidoptera, and Coleoptera. Hymenoptera was limited to bees and wasps. Sampling was conducted in Plymouth County, Massachusetts from April to November, 2016-2021. Insects were caught via pan traps and sweep netting.

Results/Conclusions

In Plymouth County, 66.1% of sampled pollinators were flies and 16.2% were bees. Wasps accounted for 10.7% of all pollinators, beetles for 6.1%, with moths and butterflies totaling 1.0%. Given abundance and effectiveness, Dipterans likely provide important pollination services worthy of further study. Four of the six sites had between 71.2-76.2% flies. The most and least urban sites had notably lower proportions of flies, 37.0% and 32.4%. Pollinator groups' abundances varied over the season and the presence of multiple pollinators throughout the season could increase plant resiliency in the face of native bee declines. Flies (r = -0.40, p < 0.001), wasps (r = -0.33, p =0.002), beetles (r = -0.38, p < 0.001), and bees (r = -0.21, p = 0.045) were all negatively correlated with imperviousness, suggesting most pollinators share a vulnerability to urbanization. Additionally, average yearly bee and total non-bee sweep net abundances had a strong positive correlation (r = 0.82, p = 0.046); pollinators appear to follow similar trends. Thus, reported bee declines may simply reflect an overall insect decline. Non-bee pollinators warrant increased attention given their prevalence, ecological contributions, and close relationship with bees.