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Publication #ENY-825

Blueberry Gall Midge: A Major Insect Pest of Blueberries in the Southeastern United States1

Oscar E. Liburd, Erin M. Sarzynski, Blair J. Sampson and Gerard Krewer2

The blueberry gall midge, Dasineura oxycoccana Johnson, feeds on developing leaf and floral buds of blueberry bushes in the southeastern United States (Figure 1). In the mid 1990s, Florida growers were re-alerted to blueberry gall midge, as researchers learned that midges affected vegetative and floral buds, a problem that was previously attributed to frost damage. Affected buds take on a dry, shriveled appearance and will often crumble when touched. Left untreated, midge populations are capable of destroying up to 80% of rabbiteye plantings. Blueberry gall midge is a major pest of blueberries in several southeastern states including Georgia, North Carolina, and Mississippi. It is also becoming an increasing problem in blueberries in Nova Scotia, New Jersey, Michigan, and Oregon.

Figure 1. 

Blueberry gall midge female

A high population of blueberry gall midge may limit the ability of bushes to produce and maintain a heavy fruit set. Symptoms of infestation include premature floral bud abortion, leaf curl, stunted growth, and blackened leaf tip (Figure 2). Both rabbiteye, Vaccinium ashei Reade and southern highbush blueberries V. corymbosum L. X V. darrowi Camp are susceptible to blueberry gall midge. However, floral buds of the earlier blooming southern highbush cultivars appear to escape the damage.

Figure 2. 

Symptoms of blueberry gall midge infestation.

Blueberry gall midges are very small insects, approximately 3 mm in size, or smaller than the average mosquito. They have long slender legs, globular cylindrical antennae, transparent wings with long black hairlike structures and reduced venation (Figure 1). The larvae are small (2 mm) and generally not easy to observe within the confines of infested buds. Females lay eggs in either floral or vegetative buds just after bud swell, when scales begin to separate and the tips of flowers become visible. A single female can lay up to 20 eggs in the mid to inner scales of the buds, which provide protection for the developing midges. Eggs hatch into larvae (maggots) within a few days and the larvae continue to develop inside the buds (Figure 3). The emerging maggots feed on plant juices within the buds, remaining unseen to the naked eye. Ultimately it is the larvae, feeding on the nutritive plant juices, which cause the debilitating symptoms associated with blueberry gall midge infestation.

Figure 3. 

Maggots emerging from an infested leaf bud.

Climatic factors including temperature and moisture plays a role in emergence dates and midge densities within blueberry plantings. In north-central Florida, milder temperatures appear to favor early emergence. Reliable monitoring techniques for detecting blueberry gall midge infestations prior to the onset of symptoms include collecting young buds and placing them into a bag at room temperature. If buds are infested, larvae will begin to emerge after 3-4 days. Several species of endoparasitoids that can kill up to 40% of the blueberry gall midge larvae have been identified. These species include platygastrids in the genera, Synopeas, Platygaster and Inostemma. In addition, a prepupal parasite, Aprostocetus sp. (Eulophidae Tetrastichinae) have been found associated with blueberry gall midge in rabbiteye bluberries.

Questions regarding the biology and management of blueberry gall midge should be directed to: Dr. Oscar Liburd, Fruit and Vegetable Entomologist, University of Florida, Gainesville, FL 32611, Liburd@ufl.edu.

References

Sarzynski, E.M. and O.E. Liburd. 2003. Techniques for monitoring cranberry tipworm (Diptera: Cecidomidae) in rabbiteye and southern highbush blueberries. 96: 1821-1827.

Sampson, B.J., T.A. Rinehart, O.E. Liburd, S.J. Stringer and J.M. Spiers. 2006. Biology of parasitoids (Hymenoptera) attacking Dasineura oxycoccana and Prodiplosis vaccinii (Diptera: Cecidomyidae) in cultivated blueberries. Ann. Entomol. Soc. Am. 99: 113-120.

Dernisky, A.K., R.C. Evans, O.E. Liburd and K. Mackenzie. Characterization of early floral damage by cranberry tipworm (Dasineura oxycoccana Johnson) as a precursor to reduced fruit set in rabbiteye blueberry (Vaccinium achei Reade) 51: 143-148.

Footnotes

1.

This document is ENY-825 (IN458), one of a series of the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: September 2002. Revised: September 2006. Please visit the EDIS Website at http://edis.ifas.ufl.edu.

2.

Oscar E. Liburd, associate professor, Erin M. Sarzynski, former student, Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611; Blair J. Sampson, entomologist, USDA-ARS, Southern Horticultural Laboratory, Poplarville, MS and Gerard Krewer, extension horticulturist, University of Georgia, Tifton, GA 31793.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean.