SELECTION OF SUITABLE TRICHOGRAMMA (HYMENOPTERA, TRICHOGRAMMATIDAE) SPECIES FOR POTENTIAL CONTROL OF THE BLACKHEADED FIREWORM (LEPIDOPTERA, TORTRICIDAE) INFESTING CRANBERRIES

Four species or strains of Trichogramma (Hymenoptera: Trichogrammatidae) were tested in the laboratory for their ability to accept and parasitize eggs of the blackheaded fireworm, Rhopobota naevana (Hubner) (Lepidoptera: Tortricidae). An indigenous species of T. sp. nr. sibericum Sorokina emerging from fireworm eggs collected from cranberry fields showed a high parasitism in fireworm eggs, whereas commercial T. minutum Riley and T. evanescens Westwood displayed a low ability of parasitism. When T. minutum from the commercial source was reared on Peridroma saucia (Hubner) (Lepidoptera: Noctuidae) for one generation, parasitism of fireworm eggs was improved. Trichogramma displayed a higher rate of acceptance and parasitization for second-generation eggs than the first-generation. Although the affinity to its natural host decreased after two generations reared on P. saucia eggs, percentages of acceptance and parasitism by T. sp. nr. sibericum after 17 generations were still higher than those of commercial Trichogramma. T. sp. nr. sibericum showed a potential to parasitize the fireworm eggs in the laboratory. A strategy for fireworm control using Trichogramma is discussed. (C) 1994 Academic Press, Inc.