Desiantha weevils are a common pest of canola seedlings in Western Australia, especially in the Albany and Esperance port zones. Growers rely on insecticide applications for weevil control. However, spray failures are reported every year.
Spray failures for the control of Desiantha weevil could potentially be due to this pest developing resistance to the synthetic pyrethroid insecticides which are the main group of insecticides used. Or the failures could be due to spray applications not being applied when the adult weevils ares actively moving in paddocks.
Through a series of bioassays, this project will investigate if Desiantha weevil populations across Albany and Esperance port zones differ in susceptibilities to insecticides.
It is clear from the current challenges with this pest and reliance on insecticides, more options, other than chemical application are needed.
Given that little is known about the biology and ecology of this pest, research will be undertaken to identify the host range for larval development and determine if weevil activity can be linked to environmental cues such as humidity, temperature, season, and photoperiod.
This information can be used to determine optimal spray windows, areas for spray application, and identify other weak links in the pest biology that could be targeted through alternative management tactics.
Improved management practices for Desiantha weevil based on its biology, means control measures can be implemented early to prevent significant crop loss. This is especially important as future projections in WA are for a shorter growing season, meaning there will not be a window for re-sowing crops, if Desiantha weevil adults or larvae cause significant seedling loss.