Agriculture

Spotted Winged Drosophila (Drosophila suzukii)


   Male SWD fruit fly, quite small, only 3mm in length, caught in cider vinegar trap.
Note black spots on wings, which are distinguishing characteristics of the male SWD.

 
 

Spotted Wing Drosophila Surveillance Program- Update July 11, 2017

Low levels of Spotted Wing Drosophila (SWD) females and males (1-2 per trap) have been found in traps in southern Manitoba.
 
Berry Crops at Risk
Raspberries: As raspberries start to change colour and ripen in mid-July, an insecticide could be applied to protect that harvest which is expected to start in 1-2 weeks time, then repeat with an alternate insecticide 7-10 days later (see list and link below).
 
Late Season June-bearing Strawberries: At risk now would be the later picking of late season June-bearing strawberries, so may not be worth spraying unless significant harvest remaining. 
 
    • As more wild hosts and other commercial berry crops begin to ripen, expect SWD numbers to start building up significantly by late July.
    • Berries are susceptible to SWD infestation from the start colour starts to appear on the berry all the way through harvest. Producers have many chemical control options to control SWD (see link below).
    • It is important to constantly rotate every application through different insecticide chemical groups to avoid potential insecticide resistance issues with SWD.  

 
Spotted Winged Drosophila (Drosophila suzukii) (SWD) is a vinegar fly of East Asian origin that can cause damage to many soft skinned fruit crops. SWD pierces seemingly healthy fruit, and lays its eggs. The eggs hatch in about 3 days, the larvae feed on the fruit and emerge as adults after 6-28 days. Early detection is critical because symptoms often do not appear until after the fruit is harvested. Commonly confused with the common fruit fly, Drosophila melanogaster, SWD differs as it attacks unripe to ripe fruit, whereas the common fruit fly feeds on overripe and rotting fruit.
 
SWD most commonly affects raspberries, strawberries, blueberries, cherries and plums. It was first identified in Manitoba in commercial berry fields in August, 2013.
 
Weekly applications of approved insecticides are quite effective at controlling SWD and protecting the berry harvest from damage. In spring 2017 Emergency Use Registration of insecticides approved for use on berries crops added SWD as an added insect pest to the labels. Treatments are available for SWD if detected early and are listed at SWD control options- Emergency Use Registration- OMAFRA factsheet. Different chemical classes must be rotated, as the insect is capable of many generations in one growing season and may develop resistance.
 
This insect pest has become widely established throughout North America. Spotted wing drosophila adults can be blown by wind to nearby locations or transported to new regions via infested fruit. It has been confirmed in neighbouring regions such as southern Ontario in 2010, Minnesota in 2012 and North Dakota in 2013. In Ontario SWD has been found in traps located near raspberries, blueberries, strawberries, cherries, apricots, grapes, currants, sea-buckthorn, plums and wild hosts. It is unknown whether SWD will overwinter in Manitoba and how early SWD will appear in the following growing season.
 
The Prairie Fruit Growers Association and Manitoba Agriculture Fruit Crops Program are working in collaboration on a province wide SWD surveillance program in the 2017 field season to provide advance warning to commercial berry producers of the presence of SWD and when to start control applications.

 

2017 Manitoba SWD Control Options- Emergency Use Registrations and Label Registrations*
Pesticide
(linked to PMRA label)
Group #
Max # Applications/ Yr
Application Interval
(in days)
Crops and Pre-harvest Interval      (in days)
 
5
3
7
Strawberry:1
Cherry: 5
Raspberry:1
Currant/ Gooseberry: 3
Saskatoon:3
5
3
5
Strawberry:1
Raspberry:1
Cherry:3
Saskatoon:3
28
4
5
Saskatoon:3
Mako
(see EUR label)
3
1
N/A
Strawberry:2
Raspberry:2
Grapes:6
Malathion 85E
(see EUR label)
1B
2 -strawberry/raspberry/currant
1-grapes
7-10
Strawberry:3
Raspberry:1
Currant/Gooseberry:3
Grapes:3

This table is only a guideline, please follow directions in the original Pest Control Product Label before using on a crop.This table is only a guideline, please follow directions in the original Pest Control Product Label before using on a crop.

 

Berry Salt Test for Larvae

Test berries for larvae using ¼ cup salt in 4 cups of water, place ripe (but not overripe) berries in a pan with the salt solution, gently break-up the berries and look for small, white larvae to float in the solution.  Salt water berry test for SWD link