Studies on Biology and Infestation Dynamics of the Bean Seed Beetle (Coleoptera, Bruchidae: Bruchus Rufimanus) inSaxony

摘要

The behavior and way of life of the bean seed beetle was studied during the growing season 2016-2018 in the field as well as in the laboratory. The focus of the observations was mainly on movement patterns of the imagines, egg development, nutrition and mortality of the beetles and their stages of development. Additionally, studies on biology were carried out.At the beginning of the flight the males dominated, later abalanced gender ratio existed, until finally the females dominated from the beginning of June. The reproduction of the beetles already starts before the flowering of the field bean. An intake of pollen to obtain the sexual maturity of females can therefore be excluded. In addition to extrafloral nectaries, the beetles demonstrably use pollen from the field bean as asource of food. Pollen from surrounding flowering plants is also accepted. Oviposition is independent of the size of the pod and begins shortly after flowering. In 2018, up to 137 eggs per pod could be detected. The larvae appear about seven days after egg laying in the eggs (black head stage). Acontrol of the hatching larvae is not useful with the currently used methods, as the larvae drill directly under the egg shell in to the pod. They are thus optimally protected against external influences. There is avery high mortality during the entire developmental period of the larvae. The bean sprout embryo is rarely damaged in the seed by the bean seed beetle larvae. Mostly the embryo is intact. Information on the development and interaction of the larvae within the seed are given. In the field, hitherto known hibernation places could not be confirmed.Most often, the beetles showed flight activity in the plant stand. For flight activity mainly short distances were coverd and the flight altitude rarely exceeded the stature of the plants. This pattern of behavior proved to be constant until the end of the activity period.In hatching experiments, only avery small proportion of bean seed beetles survived storage.