Use of Trichogramma and Bt for control of Pieris rapae in cabbage on Prince Edward Island.

Blatt, S.E., Ryan, A., Adams, S., Franklin, J.L., and Driscoll, J. (2015). "Use of Trichogramma and Bt for control of Pieris rapae in cabbage on Prince Edward Island.", Journal of the Acadian Entomological Society, 11, pp. 26-31.

Abstract

Organic cabbage growers on Prince Edward Island have limited means to control Pieris rapae (Lepidoptera: Pieridae), their main lepidopteran pest in cabbage. The use of Bt (Bacillus thuringiensis subsp. kurstaki) or spinosad products (e.g., Entrust) are common practice but repeated applications can become expensive, while parasitoid wasps (Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae)) could provide an economically feasible alternative if shown to be effective. Eight plots were established in an organic cabbage field and encircled with a fence to reduce dispersion between treatments. Four treatments (control, Bt, Bt+Trichogramma release, and Trichogramma release) were set up in these plots during the 2014 growing season. The proportion of marketable cabbages was significantly reduced in control plots compared with other treatments. Further, Bt+Trichogramma treatment resulted in significantly higher proportion of marketable cabbages than Trichogramma alone. No significant differences were observed among treatments for cabbage head weight or size. Economics and potential of Trichogramma in an integrated pest management strategy for organic cabbage production are discussed.

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