Nectar sources and age structure in a population of Aedes provocans (Diptera: Culicidae)

Gonotrophic-age structure of a population of Aedes provocans (Walker) and nectar sources used by adults were studied for 2 yr at a field site near Belleville, Ontario, Canada. Females emerged during a short period, and aging of the population was highly synchronous. Complete parity of the population was achieved within about 17 d in 1978 and 27 d in 1979. Some females completed as many as four gonotrophic cycles. This synchronous pattern of population aging is compared with patterns in other species of snow-melt Aedes, which typically age much more gradually. The pattern of synchronous aging permitted estimation of daily mortality rates from an index of population size derived from human-bait catches; peaks in the biting index were related to each gonotrophic cycle in the population. Nectar sources for adults were ranked according to abundance and the extent to which they were used by Ae. provocans, permitting a coarse, semiquantitative estimate of preferences. Ae. provocans obtained nectar from the extrafloral nectaries of one species and the floral nectaries of 19 species of angiosperms. Shrubs and trees, especially of the Rosaceae (primarily species of Prunus), were particularly important as nectar sources and bloomed concurrently with the appearance of nulliparous females. Sharp declines in the population of Ae. provocans were associated with the cessation of blooming of these plant species. It is hypothesized that the highly synchronous pattern of gonotrophic aging in Ae. provocans was attributable, in part, to the ready availability of nectar sources and bloodmeal hosts near breeding sites.