Differentiation of host-seeking behavior from blood-feeding behavior in overwintering Culex pipiens (Diptera: Culicidae) and observations on gonotrophic dissociation.

Abstract

Host-seeking behavior was differentiated from blood-feeding behavior in overwintering Culex pipiens by comparing engorgement rates in mosquitoes given access to a host in small (0.24-1) and large (3.8-1) chambers. The large chamber requires that most mosquitoes display host-seeking behavior before contacting the host, whereas the small chamber assures such contact by some mosquitoes that are not in a host-seeking mode. Data accumulated in this manner indicate that blood feeding by diapausing Cx. pipiens is rare at simulated late summer and early autumn photophases, even when warmed at 25 °C, unless the host-seeking step is bypassed by placing the mosquitoes near a host. If the host-seeking step is bypassed, some diapausing Cx. pipiens can be induced to feed and some of these may undergo gonotrophic dissociation when incubated at 15 °C and a short photophase during blood meal digestion. However, such feeding followed by gonotrophic dissociation cannot be assumed to occur in nature because host seeking is an essential element in the stepwise series of events preceding blood feeding.