SUSCEPTIBILITY OF VARIOUS MOSQUITOS OF CALIFORNIA TO SUBPERIODIC BRUGIA-MALAYI

Laboratory experiments were conducted to determine the susceptibility of six species of mosquitoes, representing three genera, to subperiodi c Brugia malayi. The black-eye, Liverpool strain of Aedes aegypti was the susceptible control. Mosquitoes were fed on microfilaremic jirds ( Meriones unguiculatus). All mosquitoes, except wild caught Culex eryth rothorax, were laboratory-reared and allowed to feed when 8 to 10 days old. Anopheles freeborni, Anopheles hermsi, and Culiseta inornata pro ved refractory. Both Anopheles species allowed invasion of flight musc le and development to the late first stage, after which larval growth ceased and melanization occurred. Culiseta inornata prevented any larv al development. Culex tarsalis and Cx. erythrothorax proved highly sus ceptible to B. malayi infection. In all, 95.6% and 88.7% of the Cx. ta rsalis harbored third-stage larvae after infective feedings of 15.7 an d 81.8 mf/mu l of blood, respectively, while only 11.5% were found sus ceptible when microfilaremia was low (1.1 mf/mu l). Culex erythrothora x demonstrated a susceptibility rate of 82.3% with 17.0 mf/mu l. Both Culex species appear to be excellent experimental hosts for subperiodi c B. malayi. This is the first conclusive evidence that mosquitoes of the genus Culex can naturally support the complete development of a st ain of subperiodic B. malayi.