Integrated Pest Management for<i>Dasineura oxycoccana</i>(Diptera: Cecidomyiidae) in Blueberry

Abstract

The ecology and control for the little-understood, blueberry bud-infesting gall midge Dasineura oxycoccana (Johnson) was studied to help reduce an estimated 20–80% blueberry crop loss due to this insect in the southern United States. Principal natural enemies were eulophid wasps, 85% of which were Aprostocetus (Perkins). Overall parasitism rate was 7% in the field, at times peaking around 34%. A 75% decline in the abundance of larval D. oxycoccana coincided with parasitoid activity between April to September. Larval Toxomerus geminatus (Say) Metz (Syrphidae) were early-season predators of immature D. oxycoccana. Prey handling took 3–10 min, with each predator eating approximately seven gall midge larvae in a 16-h period. Prebloom applications of malathion would be effective larvicides against D. oxycoccana, inducing 94% mortality in 24 h. A microbial-based alternative to malathion, spinosad, induced average mortality of 46% in 24 h. Spinosad was as effective as phosmet (50% mortality in 24 h) for D. oxycoccana control. Patterns of host plant resistance to D. oxycoccana were not obvious among 26 cultivars, accessions and species of Vaccinium. Additionally, the use of a dormancy-breaking compound, hydrogen cyanamide, could also have a deleterious side-effect: boosting gall midge populations and spurring 50% greater infestation of D. oxycoccana larvae in rabbiteye blueberry buds.