Aedes Triseriatus (Diptera: Culicidae) and La Crosse Virus III. Enhanced Oral Transmission by Nutrition-Deprived Mosquitoes1

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Abstract
Adult Aedes triseriatus , reared as larvae under a dietary regimen that produced 3 distinct body size classes [small (S), normal (N), and large (L)], were orally infected with La Crosse (LAC) virus. In all trials female mosquitoes that had endured the severest nutritional deprivation as larvae (S class) transmitted LAC virus at rates considerably higher than the mosquitoes from the moderately deprived N and nondeprived L classes (mean transmission rates of 82, 54, and 52%, respectively). While the S class mosquitoes ingested a proportionally larger infectious blood meal in relation to dry weight than the other 2 classes, the actual amount of virus ingested varied only about 0.4 log10 plaque-forming units/0.1 mg dry body weight among the 3 size classes. Thus, while enhanced oral transmission may be dose related to some extent, it is also apparent that adult mosquitoes nutritionally deprived as larvae may be physiologically less resistant to infection by LAC virus than less deprived individuals. These results indicate that virus transmission experiments conducted with adult mosquitoes reared on optimal larval diets in the laboratory may not reflect the vector capacity found in field populations. Consequently, epidemiologically important variables such as oral transmission rates may have been seriously underestimated in many previous studies.

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