Mosquito vectors of Dirofilaria immitis in southwestern Ontario
Over 3000 mosquitoes were collected in southwestern Ontario in 1980 and 1981, using a stable trap housing a dog naturally infected with Dirofilaria immitis. The following were collected: 26 Anopheles punctipennis (100% blood fed), 36 Aedes triseriatus (94.4.% blood fed), 38 Aedes sticticus (100% blood fed), 44 Aedes dorsalis (97.7% blood fed), 73 Anopheles walkeri (100% blood fed). 161 Aedes stimulans–fitehii (97.5% blood fed). 510 Aedes trivittatus (80.8% blood fed), 569 Mansonia perturbans (93.3% blood fed), 739 Aedes vexans (95.4% blood fed) and 1114 Culex pipiens–restuans (61.6% blood fed). After holding the blood-fed mosquitoes at 26 °C for 2 weeks, 1708 were identified and dissected, and the mouthparts were observed for infective third-stage larvae of Dirofilaria immitis. Infective larvae were found in 26 Aedes sticticus (96.3% positive), 33 Aedes dorsalis (89.2% positive), 406 Aedes vexans (88.8% positive), 177 Aedes trivittatus (68.9% positive), 38 Culex pipiens–restuans (7.4% positive), and 4 Aedes stimulans–fitehii (4.1% positive). Aedes vexans and Aedes trivittatus were considered the major vectors because they were collected in large numbers, fed readily on dogs, and allowed development of D. immitis to the infective stage. This is the first report of Aedes dorsalis allowing development of D. immitis to the infective stage.