Location: Southern Horticultural ResearchTitle: Biology and efficacy of Aprostocetus (Eulophidae: hymenoptera) as a parasitoid of the blueberry gall midge complex: Dasineura oxycoccana Johnson and Prodiplosis vaccinii (Felt) (Diptera: cecidomyiidae)) Author
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2012
Publication Date: 2/6/2013
Citation: Sampson, B.J., Roubos, C.R., Stringer, S.J., Marshall, D.A., Liburd, O.E. 2013. Biology and efficacy of Aprostocetus (Eulophidae: hymenoptera) as a parasitoid of the blueberry gall midge complex: Dasineura oxycoccana Johnson and Prodiplosis vaccinii (Felt) (Diptera: cecidomyiidae). Journal of Economic Entomology. 106:73-79. Interpretive Summary: In the southeastern US, two gall midge species can cause 20% to 80% losses in the yield of the rabbiteye blueberries. These serious fly pests have effective natural enemies, primarily 5 species of tiny parasitic wasps. The wasp with the greatest potential to control gall midge populations is a eulophid, Aprostocetus sp. nr. marylandensis (Eulophidae). The wasp kills both midge species, has two generations per year and constitutes one-third of gall midge parasitoids surveyed from both conventional and organic blueberry farms. Aprostocetus lay their eggs in their host’s stomachs, and the resulting larvae will voraciously consume their host as well as any other parasitoids that share the same host with them. Female Aprostocetus systematically hunt their hosts. They also prefer to sting midge larvae of assorted sizes; although, female wasps prefer large hosts, which can accommodate up to as many as three parasitic eggs. In the field, Aprostocetus females can parasitize anywhere from 40% to 100% of midge larvae.
Technical Abstract: In the southeastern US, bud-infesting larvae of two gall midge species, Dasineura oxycoccana (Johnson) and Prodiplosis vaccinii (Felt), destroy from 20% to 80% of the rabbiteye blueberry crop, Vaccinium virgatum Aiton. Fortunately, these midge larvae fall prey to five species of endoparasitic wasps. The most effective of these wasps is the bivoltine eulophid Aprostocetus sp. nr. marylandensis (Eulophidae), whose adults constitute one-third of the gall midge parasitoids surveyed from both conventional and organic blueberry farms. Broods of Aprostocetus rely on several reproductive strategies to keep sole possession of their larval hosts. As solitary endoparasitoids and facultative hyperparasites, precocial larvae of Aprostocetus consume all interior organs of their hosts and opportunistically kill rival parasitoid broods including younger siblings. To alleviate such infanticide caused by superparasitism, an Aprostocetus female can parasitize midge larvae of assorted sizes, although she prefers large hosts whose more voluminous midguts can accommodate multiple eggs. An Aprostocetus female spends an hour or more in a systematic hunt for hosts during which time she parasitizes 40% to 100% of midge larvae. Aprostocetus females could have parasitized even more hosts had they chosen to cue in on their larval feeding scars atop leaf buds.