Date of Graduation

Spring 5-21-2021

Document Access

Project/Capstone - Global access

Degree Name

Master of Science in Environmental Management (MSEM)

College/School

College of Arts and Sciences

Department/Program

Environmental Management

First Advisor

Allison Luengen

Abstract

Neonicotinoid insecticides are toxic to bees and enhance biodiversity loss due to decreased pollination. Despite the toxicity of neonicotinoids to bees, they are being applied in increasing amounts across California landscapes. To determine what measures can mitigate neonicotinoid effects on bees, I conducted a comparative analysis of toxicity for honey bees (Apis mellifera) vs. wild bees (e.g., Bombus spp. and Osmia spp.) in agriculture and urban landscapes. Then I analyzed alternative actions and current pesticide policies. While more studies are conducted in agricultural landscapes, neonicotinoids are also found at high levels (10 ng/g per bee; 11.2 ng/g in pollen) in urban environments. Neonicotinoids can persist in soil and vegetation for over 5 years and spread to untreated areas. There may be 77% more neonicotinoids in California agriculture landscapes than what is currently reported. Managed honey bees are the current surrogate species to determine pesticide risk for pollinators. However, due to life history traits wild bees are equally or more sensitive (clothianidin: LD50 20 ng/g [Bombus spp.]; 22-40 ng/g [Apis mellifera]) to neonicotinoids as honey bees. Physical and biocontrol actions are the most substitutable non-chemical alternatives, but 98% of farmers favored chemical alternatives. Policy limitations include pollinator conservation, regulation of sublethal exposure, use of seed coating, and implementing integrated pest management practices in agriculture. In California, only three local governments have policies that specifically address neonicotinoids, indicating that the local level is an area where more could be done. Recommend further restricting local neonicotinoid use and prohibit neonicotinoid-coated seeds from agriculture.

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