Lack of Adverse Effect of Transovarially Acquired La Crosse Virus Infection on the Reproductive Capacity of Aedes Triseriatus (Diptera: Culicidae)1

Abstract

The reproductive capacity of Aedes triseriatus transovarially (TO) infected with La Crosse (LAC) virus was compared to that of uninfected females. The TO-infected line was established from eggs of females that orally transmitted LAC virus to suckling mice (SM). Two adult body size classes, large and small, were produced by rearing larvae on either an optimal diet or under nutritionally stressed conditions. Several reproductive factors were then measured through 4 generations of each size class. Mean wing lengths of male and female mosquitoes in the large size (L) class were 2.89 and 3.74 mm, respectively, and in the small size (S) class were 2.59 and 2.85 mm, respectively. No significant differences were detected between TO-infected and control groups in duration of larval stage, sexratio, hatching success, time to ovarian maturation, fecundity, or adult survival through the 2nd oviposition in either the L or S classes. LAC virus infection and oral transmission rates were significantly affected by larval nutrition. Mean male and female TO infection rates were 55% (173/312) and 61% (201/333), respectively, for the L class and 69% (215/310) and 73% (224/307), respectively, for the S class. Mean oral transmission rates of LAC virus to SM by TO-infected Ae. triseriatus were also significantly higher for S females, 68% (208/307 and 181/268), than for L females, 53% (173/331 and 149/275), after the 1st and 2nd blood meals, respectively. Increased infection and transmission rates observed in S class Ae. triseriatus, however, may be negated by their reduced reproductive capacity. The mean number of eggs for S females was 48.9 compared to 73.3 for L females. These data indicate that LAC virus infection did not exert an adverse effect on the net replacement rate of Ae. triseriatus.