Combining the use of trap crops and insecticide sprays to control the tarnished plant bug (Hemiptera: Miridae) in strawberry (Rosaceae) fields

AbstractThe tarnished plant bug, Lygus lineolaris(Palisot de Beauvois) (Hemiptera: Miridae), causes severe damages in strawberry (Fragaria× ananassaDuchesne exRozier; Rosaceae) fields in Québec, Canada. Currently, only chemical insecticides successfully control that major pest. Lygus lineolarisaggregate in trap crops such as buckwheat (Fagopyrum esculentumMoench; Polygonaceae) and white mustard (Sinapis albaLinnaeus; Brassicaceae) but do not remain long enough on these plants to significantly reduce damages on strawberries. However, the attractiveness of the trap crop gives the opportunity to gather L. lineolarisin an area of the field where chemical treatments could be applied more efficiently. The aim of this study was to test the effectiveness of the combination of trap crop (buckwheat and white mustard) and chemical treatments to control L. lineolaris. Randomised complete-block design included treatment with either no trap crop, buckwheat, or white mustard row planted close to strawberry plants. Half blocks were treated with insecticide (cypermethrin) sprayed on strawberry plants (in treatment without trap crop) or directly on trap crop. We found that L. lineolariswas more abundant on buckwheat than on white mustard or strawberry plants. Insecticide application on trap crops reduced the population on these hosts, but did not reduce L. lineolarison adjacent strawberry plants. Behavioural avoidance and physiological pesticide resistance could explain this result.