Dogbane Beetle (Chrysochus auratus Fab.) as a Biological Control Agent of Spreading Dogbane (Apocynum androsaemifolium L.)

Abstract

Dogbane beetle, Chrysochus auratus, was studied for its biological control potential against spreading dogbane, Apocynum androsaemifolium, a native perennial weed in lowbush blueberry (Vaccinium angustifolium). No-choice host range experiments were conducted with common milkweed (Asclepias syriaca), periwinkle (Vinca minor), wild raisin (Viburnum cassenoides), and lowbush blueberry. There was no significant feeding on these plant species by adult dogbane beetles. Significant decreases in foliar dry weight were achieved with 16 beetles per ramet. In Nova Scotia, beetles were present in the field for 8-12 weeks beginning in late June or early July (225-335 growing degree days). Peak beetle abundance occured at 357-577 growing degree days and varied from 4-7 beetles/m2. The fecundity and fertility, timing of pupation, and number of instars were also examined. Females deposited approximately 100 eggs over a 20 day period, with an egg viability of over 90%. Pupae were found on June 1st and June 15th.