The nematode Dirofilaria immitis causes serious disease of canines in the United States. Transmitted by a variety of mosquito species, several studies have examined the prevalence of D. immitis in mosquitoes. However, no prevalence studies have focused on diurnal mosquitoes that could potentially enter homes. Mosquitoes were collected under doorway awnings at four residences to identify the diurnal blood-feeding mosquito species and prevalence of potential vectors harboring D. immitis in Jonesboro, Arkansas. Mosquitoes were collected from May to December 2016 using pheromone traps and aerial nets. Each mosquito was individually dissected and observed for larvae in the head, thorax, and abdomen to identify infective and non-infective larvae. Ten mosquito species from five genera were identified. Larvae, presumed to be D. immitis, were observed in five mosquito species, including Aedes albopictus, Anopheles quadrimaculatus, Culex pipiens quinquefasciatus, Culiseta inornata, and Psorophora columbiae and four genera, including Anopheles spp., Culex spp., Culiseta spp., and Psorophora spp. The diurnal mosquito, Ae. albopictus composed 3.4% of the total mosquitoes collected. An. quadrimaculatus and Anopheles spp. were the most abundant mosquitoes, composing 59.7 and 19.6% of the total mosquitoes collected, respectively. Of the 536 mosquitoes dissected, 60 (11.2%) were observed with D. immitis, and 33 (55.0%) of the heartworm-positive mosquitoes harbored infective (L3) larvae in the head or proboscis upon dissection. The high proportion of infective D. immitis larvae found in the mosquitoes aggregating under doorway awnings may increase the exposure of indoor dogs and cats to heartworm disease in northeast Arkansas.
Keywords: Heartworm; Mosquitoes.
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