• Topics: Entomology and Nematology  |  Price, James F  |  Nagle, Curtis A  |  Strawberry Pest Insects  | Family: Drosophilidae 

Spotted Wing Drosophila in Florida Berry Culture¹

Spotted wing drosophila (Drosophila suzukii(Matsumura), Diptera: Drosophilidae) is an invasive pest recently introduced into Florida that could affect berry production including strawberry, blueberry, blackberry, raspberry and other thin-skinned fruit.In August 2009, spotted wing drosophila was discovered in the northeast corner of Hillsborough County, after having been known in alifonia since 2008 and in Washington since earlier in 2009. As of June 2011 it had spread to several other states and 26 Florida counties. The highest numbers in Florida have been found in Hillsborough, Dade, Palm Beach, and Broward counties.

This fly, originating in the Orient, resembles the common Drosophila spp. flies that accumulate on over-ripe bananas, flats of strawberries left without refrigeration, old fallen citrus, discarded watermelon rinds, and other fruit beginning to decompose. Both flies are small (1/8 inch or 2-3 mm), have prominent red eyes and, indeed, are closely related. Wing tips of male spotted wing drosophila incorporate a dark spot that is lacking in our common drosophilids (Figure 1). Spotted-wing drosophila males and females also have dark bands on their abdomen.

Figure 1. 

Male spotted wing drosophila.

Credits: G. Arakelian, Los Angeles County Apricultural Commissioner/Weights & Measures Department

Female spotted wing drosophila possess serrations on their egg laying organ that can cut soft surfaces of sound fruit to lay eggs inside.Common drosophilid flies lack this modification and are limited to laying eggs in soft over-ripe or rotting fruit.Spotted wing drosophila eggs that hatch inside fruit become white maggots that can soften and ruin fruit in the field or can accompany harvested fruit undiscovered until the fruit are in consumers’ hands.Currently, there are no restrictions on fruit from infested farms.

Figure 2. 

Two-liter bottle trap.

Credits: J. F. Price, Univ. Florida, Gulf Coast Research and Education Center.

These traps, developed by Florida Department of Agriculture and Consumer Services, Division of Plant Industry, can be made as follows. Bore two, pencil-diameter-size fly entry holes, opposite each other, about half way between the bottom and the neck of the bottle. Tie a string below the bottle cap with a loop for hanging the trap (Figure 2). Bait the trap with a mixture of:

•

• 12 fl. oz water

•

• 1/2 packet grocery store yeast

•

• 4 tablespoons sugar

•

• 2 drops surfactant (Tween 20, or even dish detergent)

Hang the trap in shade, about chest high from a post, tree limb, etc. near the area of concern and examine at 1 week intervals. Cover the entry holes with duct tape to prevent spills during, transport. Pour the contents over a waste sink through the bottle neck and on through a kitchen strainer. The strainer retains the trapped insects only. Pour fresh water over the insects and through the strainer to remove any remaining bait that could cloud the final mixture of water and insects. Wash the remaining insects onto a white plate or dish using isopropyl rubbing alcohol in about 1/4 inch of lquid. Count male spotted wing drosophila flies under magnification.

Management practices immediately available in Florida for spotted wing drosophila are those used to manage our common drosophilids. Additional techniques of adapting tephritid fruit fly baits with toxicants are being considered and developed for strawberries, but some problems exist in transferring the procedure to the spotted wing drosophila/strawberry system.

The most important progress in managing the new pest will be achieved by implementing cultural practices that deny spotted wing drosophila their breeding sites and kill immature spotted wing drosophila inside infested fruit. This can be accomplished in a strawberry field by removing marketable berries quickly, before they are infested, and removing and properly disposing unmarketable fruit and the immature insects they may harbor.

Practices of strawberry fruit disposal should advance beyond the common routine of dropping unsalable fruit into the row middle. Any fruit not to be sold should be collected and buried or collected, covered, and sent to municipal disposal sites.

Additionally, applications of appropriate insecticides should be made as spotted wing drosophila appear. Insecticides useful to control adults and approved for strawberry include malathion, two pyrethroids, spinosad and spinetoram (Table 1). There are no insecticides available for egg or maggot control inside fruit. It is unknown how long residues of malathion or diazinon could be effective to kill spotted wing drosophila flies, but the active period of pyrethrum is very short. Consequently, recurring applications at close intervals may be required under heavy pressure, for populations of mixed life stages, or when flies move from outside sources into fruiting fields. When these conditions are absent, applications could be held to one lifecycle or longer, probably 10 days to 2 weeks or longer during much of Florida's fruit production period.

A component of tephritid management often includes large droplet applications of protein-based bait such as Nu-Lure mixed with an insecticide or GF-120 bait manufactured with spinosad insecticide. It is uncertain if such tools can be effective for spotted wing dosophila under any circumstances. However, problems maintaining adequate moisture will exist in the bait residues used in Florida's spotted wing drosophila/strawberry system. And it may be problematic to deliver sufficient quantities of effective bait and toxicant mixture in an environment of heavy feeding pressure by common drosophilid flies.

Production by vigilant and responsive strawberry growers in Florida probably will not be reduced by this new pest, so long as the present management tools remain effective and available and growers cooperate to manage spotted wing drosophila throughout the area. New management measures must be developed, though, to assure long-term control and to reduce the impacts that presently available insecticides can bring to bear on Orius spp., Phytoseiulus persimilis, and other naturally occurring or applied beneficials useful in Florida strawberry pest management.

Sources and Additional Information

Bolda, M. 2008. New fruit fly pest in strawberries and caneberries. University of California, Agriculture and Natural Resources Blogs, Strawberries and Caneberries, 21 November 2008 http://ucanr.org/blogs/blogcore/postdetail.cfm? postnum=821, viewed 1 Sep 2009.

Bolda, M. 2009. Update on the cherry vinegar fly, Drosophila suzukii, now known as the spotted wing Drosophila. University of California, Agriculture and Natural Resources Blogs, Strawberries and Caneberries, July 9, 2009, http://ucanr.org/blogs/blogcore/postdetail.cfm? postnum=1483 , viewed 1 Sep 2009.

Bolda, M. 2009. Drosophila suzukii update. University of California, Agriculture and Natural Resources Blogs, Strawberries and Caneberries, June 3, 2009. http://ucanr.org/blogs/blogcore/ postdetail.cfm?postnum=1351 , viewed 1 Sep 2009.

Cline, H. 2009. CVF causing widespread damage. Western Farm Press, 6 July 2009, http://westernfarmpress.com/citrus/cherry-fruit-fly-0706/, viewed 24 July 2009

Delfinado, M. D. & D. E. Hardy. 1977. A catalog of the Diptera of the oriental region. Vol III Suborder Cyclorrhapha. The University Press of Hawaii, Honolulu. x + 854 pp

Kaneshiro, K. Y. 1983. Drosophila (Sophophora) suzukii (Matsumura). Proceedings Hawaiian Entomological Society 24: 179.

Kanzawa, T.1936. Studies on Drosophila suzukii Mats. Journal of Plant Protection (Tokyo) 23: 66-70. 127-132, 183-191. Abstract in Review of Applied Entomology 24: 315.

Kanzawa, T.1939. Studies on Drosophila suzukii Mats. Kofu, Yamanashi Agric. Exp. Sta. 49 pp. Abstract in Review of Applied Entomology 29: 622.

Steck, G.J., W. Dixon, & D. Dean. 2009. Spotted wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), a fruit pest new to North America. Pest Alert. Florida Dept. Agric. and Consumer Services, Div. of Plant Industry. http://www.fl-dpi.com/enpp/ento/ drosophila_suzukii.html#pagecontent , viewed 1 Sep 2009.

Uchino, K. 2005. Distribution and seasonal occurrence of cherry Drosophila, Drosophila suzukii (Diptera: Drosophilidae), injurious to blueberry in Chiba Prefecture. Annual report of the Kanto Tosan Plant Protection Society 52: 95-97.

University of California Cooperative Extension, Mariposa County. Be on the look out for spotted wing Drosophila. http://ipm.ucdavis.edu/PMG/PESTNOTES/pn74158.html [13 Sep 2011].

van der Linde, Kim. 2009. Zaprionus indianus distribution in the United States. http://www.kimvdlinde.com/professional/Zaprionus%20distribution%20US.php, viewed on 1 Sep 2009.

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.

• Copyright 2009 |
• Site Feedback |
• About This Site