Potential impact of neonicotinoid insecticides on honey bees (Apis mellifera) in muskmelon production

Kira Nixon, Purdue University

Abstract

Honey bees (Apis mellifera) provide pollination services to many agricultural crops, including cucurbits. Neonicotinoids are commonly applied to cucurbits where honey bee colonies are often rented for sufficient pollination and proper fruit set. The goals of this study were to determine the potential impact of neonicotinoid residues on honey bees in muskmelon production and to determine the extent and duration of striped cucumber beetle control among treatments. The neonicotinoids evaluated were imidacloprid and its metabolites imidacloprid olefin and 5-hydroxyimidacloprid, thiamethoxam and its metabolite clothianidin, and acetamiprid. Thiamethoxam applied as a FarMore® seed treatment resulted in a highest mean pollen concentration of clothianidin at 6.48 ng/g. The highest mean pollen concentrations of thiamethoxam when applied as a Platinum® transplant water drench reached 64 ng/g, and the Actara® foliar spray reached 133 ng/g. Imidacloprid applied as an Admire Pro™ transplant water drench reached a mean pollen concentration of 96 ng/g. All of the resulting pollen residue concentrations following these treatments reached levels that have been shown to cause adverse effects on honey bees. The application of the acetamiprid Assail® foliar spray reached a mean pollen concentration of 150 ng/g which is well below the levels that have been shown to cause negative effects on honey bees. The low label rates for both soil drenches of imidacloprid and thiamethoxam provided control comparable to the high label rates. Imidacloprid provided the best protection, while both insecticides maintained populations below the economic threshold for 20 days after application at transplanting whereas the control did not. High label rate foliar sprays of acetamiprid applied as Assail® and thiamethoxam applied as Actara® both provided protection against striped cucumber beetles for 7 days after application when the control did not. The FarMore® seed treatment did not provide protection against striped cucumber beetles. The results have led to the modification of neonicotinoid product and application method recommendations to growers to maximize insecticide efficacy while minimizing honey bee health risks.

Degree

M.S.

Advisors

Foster, Purdue University.

Subject Area

Entomology

COinS