The ecology and behavior of Aedes atlanticus D. & K. and other species with reference to Keystone virus in the Houston area, Texas.

Abstract

The distribution, in time and space, of adult Aedes atlanticus, A. tormentor and associated woodland mosquito species was studied by use of light traps and man-biting collections. Peak abundance of adults of A. atlanticus, A. tormentor, A. fulvus pallens, Psorophora firox, P. Iongipalpis and P. ciliata occurred in spring and fall. Excluding midwinter months, these were the only 2 times that temporary pools were flooded. Greatest numbers of A. atlanticus and P. ciliata were collected in CDC light traps in an old field adjoining a woodland area; populations of A. infirmatus and P. longiPalpis were collected in more or less equal numbers in both woodland and field habitats. Other species, A. tormentor, A. fulvus pallens, A. triseriatlls and P. ferox , were abundant only in the woodland area. Diurnal hostseeking activity patterns were studied by a continuous 14-hr man-biting collection and a systematized 5-day series of 15-min. man-biting collections in 3 habitats: woodland area, woodland edge and old field. A crepuscular pattern was detected for A. atlanticus and A. tomentor , whereas P. ferox and P. longiPalpis were most active during midday. Host-seeking activities of A. tormentor and P. firox were greatest in the woodland area. Psorophora longipalpis was most active in the old field in early afternoon. Although A. atlanticus fed avidly in the woodland during the afternoon, most intense activity occurred in the field at sunset and gradually decreased after dark. Observations on the “depletion phenomenon” (the exponential decrease in attack rate with host exposure time) revealed that A. atlanticus and A. tormentor responded more quickly to a host during periods of peak activity than at other times. This was not observed for the attack rate of P. firox . Additional observations are reported on the depletion effect by species, habitat and time of collection. Findings are discussedin respect to the epidemiologyof Keystone virus.