Conservation of Non-Pest Whiteflies and Natural Enemies of the Cabbage Whitefly Aleyrodes proletella on Perennial Plants for Use in Non-Crop Habitats

Aleyrodes proletella causes severe economic damage to several Brassica crops. Its naturally occurring enemies often immigrate late in the season or appear in low numbers on cabbage. This field study aims to permanently increase the local abundance of A. proletella's natural enemies by providing the non-pest whitefly Aleyrodes lonicerae as an alternative and overwintering host/prey. Therefore, the population dynamics of natural enemies on different perennial herbaceous plants pre-infested with A. lonicerae were determined at two field locations over two winter periods. Most A. lonicerae colonized (on average 166.22 puparia per m²) and overwintered (342.19 adults per m²) on wood avens Geum urbanum. Furthermore, the abundance of A. proletella main parasitoid Encarsia tricolor (28.50 parasitized puparia per m²) and spiders (12.13 per m²) was 3-74 times and 3-14 times higher, respectively, on G. urbanum compared to the other experimental plants. Conclusively, G. urbanum pre-infested with A. lonicerae permanently promoted natural enemies of A. proletella by serving as shelter, reproduction, and overwintering habitat. A potential implementation of G. urbanum in conservation biological control strategies (e.g., tailored flower strips, hedgerows) against A. proletella are discussed and suggestions for future research are given.