Preliminary field experiments on exophagy of Aedes albopictus (Diptera: Culicidae) in peridomestic habitat.

Preliminary field experiments were conducted to examine the exophagy of Aedes albopictus in peridomestic habitat by using three different types of experimental buildings in Nagasaki, Japan and Chiangmai, Thailand. The density of females collected by suction traps enhanced by CO2 was high inside net-walled buildings and at outdoor sites with vegetation. On the other hand, the densities inside a normal walled building and at outdoor sites without vegetation, the microclimate conditions of both of which were different from the outdoor sites with vegetation, were low. To evaluate the effect of blocking by walls for Ae. albopictus invading to feed, an additional experiment by using a bamboo hut with openings of different sizes in the walls was conducted in Thailand. As the opening in the walls was smaller, the difference in the number of females between inside and outside of the hut became significantly larger. Therefore, the effect of physical blocking by walls was suggested. We proposed the presence of vegetation, the difference in environmental conditions inside buildings from those in vegetation due to blocking, and physical blocking by walls for invasion as ecological factors influencing the exophagy of Ae. albopictus. (author abst.)