Spotted Wing Drosophila
Identification & Biology
Photo By: Dr. Sheila Fitzpatrick
Spotted wing drosophila
Spotted wing drosophila
Photo By: Dr. Sheila Fitzpatrick
Spotted wing drosophila, adult female (showing ovipositor)
Spotted wing drosophila, adult female (showing ovipositor)
Latin Name :
Drosophila suzukii
Category :
Insects & Spiders
Description :
- Temperate fruit fly
- Adults: 2-3 mm (1/8 inch) long, brownish with red eyes and clear fly-like wings
- Eggs are 0.6 mm long, oval, white, 2 filaments at one end
- Larvae are legless, headless, up to 6 mm long at maturity, white or transparent
- Pupa are 3 mm long, brown, football-shaped, two stalks with small finger-like projections on one end
Compared to other fruit flies, spotted wing drosophila is a robust fly, but this is difficult to discern unless compared directly to other species. Many features are typical for Drosophila fruit flies, with a few key differences. Male and female characteristics are key identifiers for this species. Males have a black/grey spot on the end of each wing, as well as two black ‘combs’ or bands on the front legs. The females do not have spots or leg bands. Females have saw-like ovipositors that are used to cut into fruit skin. Ovipositors are easier to see when extended. A hand-lens or dissecting microscope is needed to confirm ovipositor presence. Spotted wing drosophila emerging in the fall overwinter as adult flies. In spring flies become active, mate, and lay eggs in ripening fruit. Spotted wind drosophila adults are spread by wind to nearby locations, and over long distances through the transportation of infested fruit to new regions.
Habitat
Spotted wing drosophila is native to Southeast Asia, preferring temperatures of 20-30 °C. It was first identified in British Columbia in 2009. It is now widespread in Coastal and Interior fruit growing areas of B.C. In BC, spotted wing drosophila has been confirmed infesting wild and cultivated raspberry and blackberry, blueberry, strawberry, cherry, peach, nectarine, apricot, plum, and suspected in hardy kiwifruit. In Interior B.C, wild hosts confirmed include Oregon grape (Mahonia sp.), blue elderberry (Sambucus cerulean), Northern black currant (Ribes hudsonianum), Tatarian honeysuckle (Lonicera tatarica), Mahaleb cherry (Prunus mahaleb), and golden currant (Ribes aureum) (H. Thistlewood, AAFC, Summerland).
Impact & Risks
- Spotted wing drosophila is known to infest thin-skinned fruit.
- Females lay their eggs inside sound fruit before harvest with their saw-like ovipositor.
- This contaminates fruit with larvae, and causes it to become soft and unmarketable.
- Larvae hatch and feed within the fruit, causing softening in the area of feeding.
- There can be several larvae in a fruit.
- Holes the size of pin pricks are evident within the soft areas of infested fruit.
- These holes result from egg laying and are used as breathing holes by larvae.
- In addition, these holes provide entry points for diseases such as brown rot and botrytis.
Prevention & Mitigation
Management recommendations include:
- Registered insecticides.
- Good harvest and sanitation practices, such as culling soft fruit, destroying culls, and keeping processing areas and equipment free of old fruit.
Treatment & Disposal
Okanagan Distribution
Priority Level Definitions
Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.
