Project Overview

Reports

Commodities

• Agronomic: hay, other

Target Pests

Practices

• Pest Management: chemical control, cultural control, economic threshold, forecasting, pesticide application timing, pesticide resistance management

As alfalfa production increases in Nebraska and remains an important crop across states in the central Midwest in recent years, challenges in alfalfa weevil management require research and extension to address the knowledge gaps. Specifically, insecticide (pyrethroid) resistance of alfalfa weevils has been confirmed across western states, but whether alfalfa weevil populations in the central Midwest have developed resistance to insecticides is unknown. In addition, observations of changes in alfalfa weevil phenology in the spring, likely due to warmer winters in recent years, could increase the difficulty in controlling them by timely insecticide applications. The objective of this project is to assess the susceptibility/resistance of alfalfa weevils to commonly used insecticides and to study their spring phenology and overwinter biology to address current challenges in alfalfa weevil management. Glass-vial bioassays will be utilized for resistance screening for alfalfa weevil larvae. Alfalfa biotype composition will be determined, and its effects, if any, on insecticide susceptibility will be unraveled. Alfalfa weevil emergence in the field will be monitored throughout the spring to study phenology and overwintering biology. Results from susceptibility bioassays will inform the current resistance status of alfalfa weevils and whether biotypes affect their susceptibility in the central Midwest. Findings of current spring phenology and overwintering biology could be used to better predict alfalfa weevil populations. Altogether, our research output will provide up-to-date information on alfalfa weevils that could be used to update and improve IPM programs.

1. Assess pyrethroid susceptibility of alfalfa weevil in the central Midwest
2. Determine biotypes of alfalfa weevil and their effects on insecticide susceptibility in the central Midwest
3. Investigate alfalfa weevil spring phenology and overwintering biology in Nebraska