Banker plants promote functional biodiversity and decrease populations of the cabbage whitefly Aleyrodes proletella

Abstract

In this study, potential banker plant systems against the cabbage whitefly Aleyrodes proletella Linnaeus (Hemiptera: Aleyrodidae) were developed under controlled conditions. The two most promising banker plant systems, that is, the parasitoid Encarsia tricolor Förster (Hymenoptera: Aphelinidae) either with Aleyrodes lonicerae Walker on European columbine (columbine system) or with Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) on Hokkaido squash (pumpkin system), were further evaluated in the field. Although the pumpkin system produced three times more parasitoids than the columbine system, both banker plants led to an 1.5-fold increase in A. proletella parasitism rates. However, only the pumpkin system increased the abundance of syrphid larvae on cabbage by 61.5% and reduced A. proletella populations on average by 4.4%–25.8% depending on the respective assessment date. In conclusion, the pumpkin system revealed to be a promising (supplementary) control measure against A. proletella. Options for further improvement and standardization of the pumpkin system as well as a potential implementation in cabbage production are discussed.