Density and distribution of Dirofilaria immitis (Nematoda : Filarioidea) third-stage larvae in Aedes sollicitans and Aedes taeniorhynchus (Diptera : Culicidae)

Numbers and the distribution of third-stage larvae (L3) were investigated i n Aedes sollicitans (Walker) and Aedes taeniorhynchus (Wiedemann) female mo squitoes fed Dirofilaria immitis (Leidy) infectious-blood with densities of microfilariae (mf) ranging from approximate to 7,100-43,400 mfi mi. At eac h microfilarial density, a maximum of 63-66 infective larvae were recovered from an Ae. sollicitans alive on day 15 after infection. In comparison wit h Ae. taeniorhynchus, Ae. sollicitans averaged greater numbers of L3 and fr om 1.4 to 2.4 times more L3 in the head and labium per infected female. The trend was for greater numbers of L3 to be found in the labium than in the head of Ac. sollicitans, but there were no significant differences between numbers of L3 recovered from these sites in differentially infected females . However, numbers of L3 recovered from the head versus the labium of diffe rentially infected Ae. taeniorhynchus varied significantly with the infecti ous blood microfilarial density. At the two lowest and highest microfilaria l densities, greater numbers of L3 were recovered from the head and labium, respectively. Variations among species in the female body size, blood meal size, and retention of L3 may be factors responsible for differences obser ved between the total numbers and percentage distribution of D. immitis L3 recovered from the simultaneous blood-fed Ac. sollicitans and Ae. taeniorhy nchus.