Hibernation and migration of Aleyrodes proletella in Germany

Abstract: The cabbage whitefly Aleyrodes proletella is a well known pest of vegetable brassica species. Since more than a decade, it is a constant and relevant pest in Germany with mass reproduction particularly on Brussels sprouts, kale, kohlrabi, and savoy. Produce quality is affected by the presence of the insects; furthermore, the produce is contaminated with honeydew and sooty mould fungi.The reasons for this increasing relevance are not clear and until now, there is only little information available on the population dynamics of A. proletella. First questions are related to the hibernation habitat and the migration behaviour. In northern Germany oilseed rape offers an exclusive hibernation habitat for the cabbage whitefly. With the ripening of the rapeseed plants in May/June, young adults leave the crop searching for new host pants. In the warmer western and south-western vegetable production areas rapeseed is not available. In these areas overwintering cabbage crops represent the most suited hibernation host. Invading of spring planted cabbage crops takes place from May to July. Depending on the weather conditions in spring and summer and the availability of hibernation hosts, A. proletella is capable of mass reproduction with up to 60,000 larvae per plant, which was found in Brussels sprouts in September 2010.