About this Environmental Science article

Seed production and seed predation in a patchy and time-varying environment. Dynamics of a milkweed ? tephritid fly system by C. Solbreck; B. Silln-Tullberg is a Environmental Science article available to read on EtoBox.

Vincetoxicum hirundinaria is a longlived perennial herb. Its pod production was measured during seven years in about 40 small isolated patches in two study areas in southeastern Sweden. Total pod production in the two areas varied synchronously and up to about 200 times between years. This variation was mainly due to drought conditions as determined by the interplay of weather (sunshine h) and site characteristics.Populations of a univoltine tephritid fly, euphranta connexa, whose larva feeds on V. hirundinaria seeds in the maturing pods, were monitored for five and seven years in the two study areas respectively. Larval fly populations in the two areas varied 30 and 50-fold between years, with highs in years when pods were abundant and lows when pods were scarce. The percentage of pods attacked by E. connexa, however, varied in the opposite direction, with very high attack rates (about 100%) when pods were scarce and low rates (down to 10-20%) when pods were common. Thus the temporal tracking of food resources by E. connexa was poor, resulting in yearly variations in the amount of unattacked pods (and seeds) being about 2,00-fold.Many host plant patches were small and totally with

Author

C. Solbreck; B. Silln-Tullberg

Publisher

Springer-Verlag; Springer Verlag; Springer Science and Business Media LLC (ISSN 0029-8549)

Published

1986

Language

EN

Field

Environmental Science (Physical Sciences)