Project Number: 5428-21000-013-17
Project Type: Specific Cooperative Agreement

Start Date: May 01, 2008
End Date: Apr 30, 2013

Objective:
To evaluate the the toxicity of a new pesticide, Rimon, on the alfalfa leafcutting bee. Rimon is a growth regulator inhibitor and is suspected by some beekeepers to be affecting the growth of bee larvae. The pesticide is used in alfalfa seed fields to control lygus bugs. The two main goals of this project are to assess egg mortality when adult bees are treated with Rimon, and evaluate the mortality dose response of eggs and larvae when pollen provisions are treated.

Approach:
Rimon® is a chitin inhibitor insecticide used for the suppression of lygus bug, the most damaging insect in Utah alfalfa seed fields. The active ingredient in Rimon interferes with insect pest development and successful molting, but is supposed to be safe on beneficial and pollinating insects. In the fall of 2007, several Idaho alfalfa seed growers noticed a greater percentage of leafcutting bee cells containing pollen/nectar provisions with no live bee brood from fields that were treated with Rimon. Growers questioned if Rimon could be lethal or sublethal to leafcutting bee eggs or larvae. The potential negative health effects of Rimon on leafcutting bees are valid concerns for growers who will have to purchase more new bees each growing season. This project will provide basic information on the lethal or sublethal effects of Rimon on adult and immature alfalfa leafcutting bees used to pollinate alfalfa using controlled exposures in the laboratory. ARS will provide a supply of bees and expertise in bee biology and how to handle the bees for development and mortality studies. The University will conduct the experiments, analyze the data, and write up the reports.