Establishment and dispersal of Urophora affinis (Diptera: Tephritidae) and Metzneria paucipunctella (Lepidoptera: Gelechiidae) in southwestern Virginia
1996
Mays, W.T. | Kok, L.T.
Two European gall-producing insects, Urophora affinis Frfld. (Diptera: Tephritidae) and Metzneria paucipunctella (Zeller)(Lepidoptera: Gelechiidae) were introduced into Virginia in 1986 for biological control of spotted knapweed (Centaurea maculosa Lam.). Adults of U. affinis (n = 2625) and M. paucipunctella (n = 450) were released at two sites in Montgomery County, Virginia, and their populations were monitored yearly by dissecting spotted knapweed flower heads. Beginning in 1992, knapweed samples collected at various distances from the release sites were checked for dispersal. U. affinis is well established and is spreading slowly. The number of larvae per flower head and the seed numbers are inversely related as plants with the greatest number of larvae per spotted knapweed head had the lowest number of seeds. Knapweed density has declined at one of the release sites which had the highest rate of infestation by U. affinis. Establishment of the moth, M. paucipunctella, is less certain as it has been recovered at a very low level from only one site.
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