Population age composition and female longevity of the arbovirus vector Culex annulirostris skuse near Echuca, Victoria, in the Murray Valley of southeastern Australia 1979-1985.

Abstract

A population of Cx annulirostris in a state forest near Echuca, Vic., was sampled with a dry ice-baited encephalitis virus surveillance (EVS) trap from 1979 to 1985, generally on a fortnightly basis. These collections were combined for monthly samples which were dissected for parity and population age composition. The proportion parous varied between months and between years; for mid-summer (February) proportion parous ranged from 0.54 to 0.83. There was no evidence that the population was autogenous. Monthly average duration of the gonotrophic cycle was estimated for October to May, and ranged from 4 days to 12 days. The probability of survival through one day in summer, taken from the proportion surviving from 1-parous to 2-parous, averaged 0.75 over 3 years. This average was higher (0.89) if calculated from the proportion parous. Females old enough to transmit Murray Valley Encephalitis (MVE) virus were recorded from October to May, and represented up to 15.8% of the total collection in one season (1979-80).