- Drosophila suzukii is an invasive and economically important pest of many soft-skinned fruits such as blueberries, blackberries, raspberries, strawberries, cherries, and other fruits. The SWD flies have brownish-yellow thorax, black stripes across the abdomen, and distinct red eyes. Males have dark spots on the wingtips and black combs on the forelegs. Female SWD lack the spots and black combs, but have a very large serrated ovipositor. The adult female punctures the skin of intact fruit using its serrated ovipositor and deposit white eggs just under the fruit skin. Two spiracles which are attached to the egg extend out of the fruit through the hole, also known as a sting. Eggs hatch after 1-3 days and the larvae (maggots) continue to feed in the fruit.
- Since its first detection in California in 2008, SWD spread rapidly across the United States. It was first found in Georgia in 2010 and since then SWD has been reportedly detected in many counties across the State. However, a statewide survey is underway to confirm reports and develop a SWD distribution map in the State of Georgia.
- Ecological Threat
- D. suzukii was first found in Georgia in 2010 and since then this small vinegar fly has impacted the $255 million Georgia blueberry industry with crop losses of up to 20% annually.
- Adult males may not develop the characteristic spot on the wingtips until 10 hours after eclosing, and reproductive maturity will typically be reached after 1-2 days. Mature females are extremely productive, laying 1-3 eggs per oviposition site, in 7-16 sites per day, for 10-59 days. One female can produces 300-600 eggs within a lifetime.
- While in the fruit, the larvae develop through three instars. The respiratory ducts and mouth of the larvae develop with each instar. The third instar (Figure 3) has large hook-like mouthparts and branching anterior spiracles which protrude through its larval exterior. After 5-7 days, the third instar exits the fruit to pupate. The puparium is initially bright white, but it browns as it ages. The fly remains in its puparium for 3-15 days until the adult emerges.
- Measures to control Spotted Wing Drosophila are available, but methods are constantly being refined as new research and information becomes available, so keep informed through your local County Agents, and through our UGA Blueberry Blog. Currently there is no economic threshold for SWD, and the benefits of the treatment significantly outweigh the costs. We are therefore recommending a conservative approach, if SWD is detected at your or at your neighbor’s farm, then control measures must be implemented. SWD control involves cultural control methods and/or chemical control methods.=SUMMARY=
In summary, SWD is clearly one of the most devastating pests in the history of Georgia blueberry production. It is therefore extremely important for growers to implementing management strategies in a proactive manner in order to minimize the impact of this pest. Following are the key components of effective management of SWD:
- Monitor fields with traps and check the traps weekly starting from the fruit-set until the end of harvest.
- Make sure to check the trapped flies and correctly identify SWD to determine presence and number of male and female SWD.
- Once SWD is detected in the traps while the berries are ripening or ripe, apply effective insecticides registered for blueberries to protect the fruit. For detailed information about insecticides for SWD in blueberries (see Table 1 and Table 2, and also other resources available locally http://www.ent.uga.edu/labels/BlueberryInsecticide.pdf and regionally http://www.smallfruits.org/SmallFruitsRegGuide/Guides/2014/BlueberrySprayGuide11252013.pdf).
- Make sure to rotate classes of insecticides to delay the development of insecticide resistance.
- Continue monitoring to evaluate your management program, and respond in a timely manner if needed.
- If possible, harvest frequently and remove leftover fruit from the orchard to reduce fly feeding and breeding resources.
- Keep yourself updated about this pest to informed decisions to manage it. Find the latest information at our UGA Blueberry Blog (http://blog.caes.uga.edu/blueberry/) and sign up to receive updates instantly.
|Table 1. Registered Insecticides for Spotted Wing Drosophila Management|
|Trade Name||Chemical Name||Class||Application Rate (per acre)||Pre-Harvest Interval (days)||Re-Entry Interval (hours)||MRL* U.S.||MRL* Canada||SWD Activity|
|Malathion 8F||Malathion||Organophosphates||2.5 pint||1||12||8||8||E|
|Imidan 70WP||Phosmet||Organophosphates||1.33 lb||3||24||10||5||E|
|Mustang Max 0.8EC||Zeta-cypermethrin||Pyrethroid||4 oz||1||12||0.8||0.1a||E|
|Danitol 2.4EC||Fenpropathrin||Pyrethroid||16 oz||3||24||3||3||E|
|Asana XL||Esfenvalerate||Pyrethroid||9.6 oz||14||12||1||0.1a||E|
|Brigade 10WSB||Bifenthrin||Pyrethroid||16 oz||1||12||1.8||0.1a||E|
|Hero 2.1EC#||Bifenthrin + Zeta-cypermethrin||Pyrethroid||6-10.3 oz||1||12||1.8, 0.8||0.1a,0.1a||E|
|Pyganic 1.4EC||Pyrethrin||Pyrethrin||64 oz||0.5||12||1||1||F|
|Entrust 80WP||Spinosad||Spinosyn||2 oz||3||4||0.25||0.5||G|
|Delegate 25WG||Spinetoram||Spinosyn||6 oz||3||4||0.25||0.5||E|
|Assail 30SG||Acetamiprid||Neonicotinoid||5.3 oz||3||1.6||1.6||G|
|Exirel||Cyantraniliprole||Anthranilic Diamide||13.5-20.5 oz||3||12||4||4||E|
- * The maximum residue limit is provided for U.S. and Canada. Check http://www.mrldatabase.com for MRLs in other countries.
- a No MRL set, so default MRL is shown. Check with your marketers on their export policy.
- # Hero is a mixture of bifenthrin and zeta-cypermethrin (ingredients in Brigade or Bifenture and Mustang Max). Carefully check the rates used of these products so you do not exceed the total seasonal limit for both active ingredients.
|Table 2. Suggested insecticide rotational programs for Spotted Wing Drosophila Management in Georgia Blueberries|
|Management Strategy||Weekly rotations|
|Export-friendly, maximum modes of action||Imidan (phosmet), Malathion 8F, Delegate (spinetoram), and Danitol (fenpropathrin)|
|Short pre-harvest interval (PHI)||Mustang Max (zeta-cypermethrin) and Malathion 8F|
|Reduced risk||Delegate and Exirel (cyantraniliprole)|
|Organic production||Entrust and Pyganic|