Parasitism of Acrobasis vaccinii (Lep:Pyralidae) by Indigenous Trichogramma (Hym:Trichogrammatidae) on Cranberries in Massachusetts

Rebecca C. Miller

Among bog, within bog, and seasonal trends in infestation of cranberries by Acrobasis vaccinii (Riley) and parasitization of A. vaccinii eggs by indigenous Trichogramma spp. were assessed on six abandoned cranberry bogs in Massachusetts. Sentinel A. vaccinii host eggs indicated that Trichogramma was present in the uplands surrounding the bogs and on the bog before Trichogramma was found to be parasitizing A. vaccinii eggs on cranberries on the bog. Weekly collections of cranberries from the six bogs showed that the rate of parasitization did not follow the same patterns as A. vaccinii egg infestation. The two bogs with the lowest cumulative parasitization levels had the highest A. vaccinii egg infestation levels, while the three bogs with the highest cumulative parasitization had the lowest egg infestation levels. One bog site had a very low A. vaccinii egg infestation so the level of parasitization could not be assessed. Both parasitization and egg infestation levels varied significantly from bog site to bog site. Parasitization was significantly greater in the middle of the bog, while there was a slightly higher rate of infestation at the bog edge. Physical and ecological characteristics of the bog sites were compared to seasonal total A. vaccinii egg infestation and parasitization for each bog. There was a weak relationship that seasonal parasitization was higher on larger bogs. Potential use of Trichogramma in pest management strategies for A. vaccinii is considered.