INOCULATIVE RELEASE AND ESTABLISHMENT OF HOLCOTHORAX-TESTACEPIES (HYMENOPTERA, ENCYRTIDAE), A PALEARCTIC AGENT FOR THE BIOLOGICAL-CONTROL OF PHYLLONORYCTER SPP (LEPIDOPTERA, GRACILLARIIDAE) IN CONNECTICUT APPLE ORCHARDS

In May 1988, inoculative releases (almost-equal-to 6,000 adults per si te) of a Japanese strain of the encyrtid Holcothorax testaceipes (Ratz eburg) were made in the center of two unsprayed and two sprayed Connec ticut apple orchards infested by Phyllonorycter spp. The encyrtid beca me established only at unsprayed sites, killing between 1 and 35% of p arasitized larvae of Phyllonorycter blancardella (F.) in generations e xamined between 1988 and 1991. The proportion of parasitized larvae ki lled by H. testaceipes was higher in the first and third generation th an in the second generation, which was a pattern sometimes observed in the endoparasitic Pholetesor ornigis (Weed). The relative amount of m ortality caused by H. testaceipes differed between unsprayed sites. In all orchards, the braconid P. ornigis or the eulophid Sympiesis maryl andensis Girault tended to dominate parasitoid guilds both before and after the release. The total amount of parasitism was higher at unspra yed than at sprayed sites, and parasitism by H. testaceipes was higher in the first than in the second generation. The amount of parasitism by the encyrtid was distributed uniformly throughout orchards in four of six (66.7%) generational samples. After the first generation of 198 8, the mean distance of progeny from the bee where adults initially we re released was similar in each generation within an orchard. In unspr ayed orchards, the density in the generation of the release was 1.0-1. 7 mines per 100 leaves, and density never exceeded 6.1 mines per 100 l eaves thereafter. Persistence at low mine densities, oviposition in le afminer eggs, and rapid dispersal after release are desirable attribut es of H. testaceipes, but its widespread establishment in commercial o rchards will depend on modifying current chemical control programs or releasing a resistant strain.