Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 29, 2005
Publication Date: January 1, 2006
Citation: Sampson, B.J., Rinehart, T.A., Liburd, O.E., Stringer, S.J., Spiers, J.M. 2006. Ecology of endoparasitoids (hymenoptera) attacking cranberry and blueberry tipworms dasineura oxycoccana johnson and prodiplosis vaccinii (diptera: cecidomyiidae). Annals of the Entomological Society of America, Vol 99, No.1, pp 113-120. Interpretive Summary: Tipworms are serious blueberry pests that reduce crop yield by killing flowers and damaging leaves. Two species are involved. The cranberry tipworm specializes on flower buds and the blueberry tipworm feeds largely on vegetative buds. Commercial pesticides offer short-term control, usually about 14 to 21 days. However, it was five newly discovered species of parasitoid wasps that effectively controlled tipworms for 200 days per year. Synopeas were the most important parasitoid wasps that laid eggs in newly hatched tipworm larvae. Aprostocetus was another common parasitic wasp that preferred to sting and lay eggs in the bodies of mature tipworm larvae (prepupae). Insecticides may be needed to protect early flower buds from cranberry tipworms, but there appears to be no immediate need for blueberry tipworm control, but more research is needed to assess the destructiveness of this newly discovered blueberry pest.
Technical Abstract: Cranberry and blueberry tipworms, Dasineura oxycoccana (Johnson) and Prodiplosis vaccinii (Felt), respectively, were recently discovered economic pests of cultivated blueberries in the Southeastern United States. Insecticides give short-term tipworm control, but overlap in the lifecycles of various parasitoid species may be more critical to sustained biological control. Field sampling, laboratory rearing and mitochondrial DNA sequencing of juveniles and/or adults identified at lease five undescribed species of diurnal endoparasitoids that jointly parasitized and killed 30 to 40 % of tipworms over a 200 day period in a density-dependent manner. These parasitoids included Platygastridae (Synopeas 2 spp., Platygaster sp., Inostemma sp.) and a tetrastichine Eulophid (Aprostocetus sp.). Platygastridae developed as solitary koinobionts, but in third instar hosts they became vulnerable to facultative hyperparasitism or symparasitism from a prepupal idiobiont, Aprostocetus. Nevertheless, the combined parasitism rates achieved by Synopeas and other Platygastridae consistently remained ~5 times that of Aprostocetus. Biological control of D. oxycoccana during blueberry flowering was limited by an intrinsic delay in parasitoid emergence and activity, which may necessitate the application of a prebloom insecticide to protect burgeoning flower buds in late winter or early spring. Parasitoids effectively curbed population growth of P. vaccinii, but overuse of insecticides intended for other pests could remove as mortality factors these parasitoids resulting in resurgence in blueberry tipworm population and vegetative bud damage in the late spring and fall.