Distribution

Since its introduction in 2008, SWD spread rapidly throughout the continental U.S. By 2013 only eight states were free of SWD: Arizona, Nevada, New Mexico, Oklahoma, Kansas, Nebraska, South Dakota and Wyoming. A thorough description of SWD spread through the U.S. can be found here (https://www.cabi.org/isc/datasheet/109283).

Predicted swd global distribution generated by the GARP algorithm.
Dos Santos et al., 2016. PLOS One.

Biology

As a polyphagous pestiferous fly, SWD shows extreme plasticity in their development time based on temperature and humidity. Since its introduction, extensive efforts have been made by researchers to understand how temperature and humidity impact the fly’s development. Below is a brief description of what we know thus far. For more information visit our Resources page.

Resources

The fly has four different life stages: egg, larvae, pupae, and adult. It can take anywhere from 10-23 days to develop from egg to adult depending on the temperature. Adult flies can live between 2 to 9 weeks, and begin to overwinter once temperatures drop below 40°F. Individual female flies can lay between 100-600 flies and eggs can hatch anywhere from 2 hours to 3 days depending on the temperature.

Female flies have a large, saw-like ovipositor on the tip of their abdomens that they use to pierce the soft flesh of ripening fruit. Unlike other non-D. suzukii drosophilid flies that lay eggs primarily on decaying and rotten fruit, SWD attack only blushing and ripening fruit. Once a female has pierced through the flesh to lay her egg it hatches and the developing larvae proceeds to feed on the inside of the fruit. The wounds caused by females’ saw-like ovipositors also leave the fruit susceptible to secondary microbial infection.

Image created by Beverly Gerdeman, Washington State University.

As a highly polyphagous fly species, D. suzukii exploits several non-crop plant species. Larvae have been reported developing on Oregon grape, Cornus spp., dogwood, milkflower cotoneaster, Autumn olive, cascara buckthorn, spicebush, blue honeysuckle, mulberry, wild cherry, cherry laurel, Portuguese laurel, Himalaya blackberry, salmonberry, black elderberry, sweet box, bittersweet nightshade, snowberry, bunchberry, dewberry, Japanese honeysuckle, Rubus allegheniensis, Rubus occidentalis, Cornus amomum, Lonicera morrowii, Phytolacca america, Rhammus cathartica, and Solamum dulcamara. Adult D. suzukii adults are also attracted to and develop on the economically important crop plants: mulberry, fig, blueberry, cherry, raspberry, strawberry, and blackberry.