2014 Ontario Trap Catches: Spotted Wing Drosophila

Table of Contents

  1. Current Update for Ontario
  2. SWD historical data
  3. Links to weekly updates in other regions

This project was made possible by the Ontario Berry Growers Association and the Ontario Highbush Blueberry Growers Association. Funding assistance to the OBGA was provided by Dow AgroSciences Canada, Engage Agro Corp., Bayer CropSciences Inc. and E.I. du Pont Canada Company. We are grateful for the continued support of the HJ Heinz Co. for the apple cider vinegar used as bait in our traps.

This project was also funded in part through Growing Forward 2, a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of Growing Forward 2 in Ontario.

Current updates for Ontario

October 24 - by Pam Fisher, Berry Crop Specialist

With OFIP II funding from the Ontario Berry Growers Association and the Ontario Highbush Blueberry Growers Association we continued with a regional monitoring program for SWD in 2014. Using the information from our monitoring program we were able to provide regular updates to growers on SWD populations in their regions. This year we hired a student in the Brighton office and put greater emphasis on monitoring for SWD in eastern Ontario. We confirmed that SWD is a problem throughout the province. Although populations east of Toronto built up later than those in southern Ontario, the patterns of fruit infestations were similar to the rest of the province. Summer red raspberries became infested towards the very end of the harvest season, and at less risk in the east. Blueberries and fall bearing raspberries were infested about a week later in eastern Ontario compared to southern Ontario. A full report of the SWD project will be available in a few weeks, and shared with members in newsletters and presentations throughout the winter.

Meanwhile, last month I had the opportunity to attend the Northeastern Spotted Wing Drosophila working group meeting at the Hudson Valley Lab in Highland, New York . It has been three years since this informal group formed and this is the third meeting. A lot has been accomplished and learned in this time. However, basic questions about the behaviour of this pest remain unanswered. Researchers still do not know for sure if SWD overwinters in northeastern America or if it re-infests our regions every year. Here are some highlights of reports and discussion from this meeting:

  • Research continues on attractants and baits for SWD traps. The best home-made bait is an apple cider vinegar plus yeast/wheat bait. Several commercial baits have been developed and have been tested, including the Suzuki bait, the Trece lure and Kumbucha tea. Each product has its pros and cons and we are still looking for strong, attractive bait for SWD that does not attract other fruit flies and sap beetles. Until we get a more selective bait, it is not practical to sift through the large volumes of insects trapped, in order to identify the first SWD on a farm.
  • Exclusion netting has been tested for SWD control in both Quebec and in New York. When exclusion netting is used properly it is an effective way to control SWD on blueberries (Figure 1). However, at present , this method of control seems prohibitively expensive.
  • Other researchers are looking at an "attract and kill" strategy for SWD control. Researchers are testing various attractants that will lure SWD to insecticide bait. These could be applied to around the field to attract and kill SWD. This research is very promising, but still far from commercial use.
  • Several researchers have tried mass trapping of SWD without success.
  • Harvest management and postharvest management are very important for SWD control. When nights are warm ( ie over 16ºF) SWD populations increase rapidly. Picking daily and maintaining a cold chain as harvested fruit moves through to market is very important. When harvested fruit is cooled and kept cool for 2-3 days, most SWD eggs and small larvae in fruit are killed.
  • SWD infestations are higher on fruit in lower canopy. Spray coverage is really, really important.

I also attended the thesis defense for Lisa Emiljanowicz, a master's student at the University of Guelph, who looked at the life cycle and biology of SWD in the lab.

  • Lisa M. Emiljanowicz, Geraldine D. Ryan, 1 Aaron Langille, and Jonathan Newman
    School of Environmental Sciences, University of Guelph, Guelph, Ontario N1G 2M7 Canada
    J. Econ. Entomol. 107(4): 1392Ð1398 (2014);
    Development, Reproductive Output and Population Growth of the Fruit Fly Pest Drosophila suzukii (Diptera: Drosophilidae) on Artificial Diet.

One of the take-home messages for me from Lisa's presentation was the fact that at any point in time, only 8% of the SWD population is in the adult stage. That means that for every 8 adults in traps, there are at least 92 SWD eggs, larvae of pupae in fruit! No wonder traps are not that effective at predicting the populations! You will have a better chance of finding the first SWD by floating fruit in salt water and looking for larvae.

Figure 1: Exclusion netting used on 1/2 ace of highbush blueberries.

Figure 1: Exclusion netting used on 1/2 ace of highbush blueberries.

Sept 9 - SWD is present in all regions of Ontario where fruit is grown. Last week we trapped the first SWD, which is our first capture for SWD at our northern site in New Liskeard.

SWD numbers typically increase exponentially in late summer and fall. Day neutral strawberries, blackberries and fall bearing raspberries are all at high risk at this time. This past week we have had several reports of damage from day neutral strawberry growers. SWD flies have been reared from blueberry and raspberry fruit collected at the end of August in both eastern and western Ontario.

Remember:

  • Weekly insecticides and thorough frequent harvest are important components of an SWD control program.
  • Keep fruit in the cooler.
  • Rimon, Beleaf, and Assail have little or no effect on SWD.
  • Malathion, Delegate and Entrust are effective.
  • If you plan to continue harvesting fruit for the next few weeks, get unmarketable fruit off the plant and out of the field.

For more information, visit: www.ontario.ca/spottedwing.

Your feedback is important to us! Please let Pam Fisher (OMAFRA's Berry Specialist) know how this pest has affected your business. You can reach Pam by email at pam.fisher@ontario.ca or by phone at 519-426-2238.

August 19 - SWD has been trapped in almost all regions , including eastern Ontario. We have not yet trapped SWD in New Liskeard, our only northern site. We do not have enough SWD traps in northern Ontario to definitely say SWD is a problem there or not this year. Across the rest of Ontario, trap counts continue to climb as SWD populations increase .

All ripening berry crops are at high risk for SWD damage at present, regardless of trap captures on your farm. This includes blueberries, blackberries, fall bearing raspberries, elderberries, day neutral strawberries. WE have collected over 200 fruit samples from wild hosts and commercial farms this summer. Recently we have noticed an increase in SWD emerging from fruit collected the around August 6-7. This means that SWD is not only migrating into your fields from wild hosts, but it is multiplying within your fields where fruit is present. We have recently observed infested raspberries in both eastern and western Ontario, and infested blueberries and day neutral strawberries in western Ontario since early August. Damage is worse where insecticides have not been applied.

All growers with susceptible fruit should be actively managing SWD, using all of the following strategies:

  • Weekly insecticide applications with a registered product.
  • Frequent and thorough harvest of all ripe fruit in the field. This means going over raspberries daily except for days missed due to pesticide application, strawberries every 2-3 days and blueberries as often as possible.
  • Immediate cooling of harvested product.

How can you help: your feedback is needed. Please help us assess the economic cost of SWD to your business by sharing your notes on crop losses and extra expenses to manage SWD. This information helps to support emergency and minor use registrations. Please send comments to pam.fisher@ontario.ca.

For more detailed SWD updates, registered products, etc, see www.ontario.ca/spottedwing

We would like to thank all the participating growers, scouts and consultants who provided monitoring sites, picked up traps and counted SWD this year. We used OFIP 2 funding through the Ontario Berry Growers Association and the Ontario Highbush Blueberry Growers Association to place a student in eastern Ontario and to hire a part time assistant help to process samples in Guelph. WE appreciate the help of 10 scouts and consultants from agribusiness who volunteered their time. We were also assisted by over 15 OMAFRA students and staff.

August 14 - blueberries, blackberries and fall-bearing raspberries at high risk

Spotted wing drosophila is now present throughout most of Ontario. With the exception of northern Ontario ( ie North Bay, Sudbury and further north), most berry growers should assume this pest is present on your farm. We do not have enough traps to definitely say if SWD is a problem in northern Ontario or not - so growers there should be on the look-out. Do salt tests and check fruit for damage on a regular basis.

Otherwise, we have trapped SWD at most sites across Ontario and numbers are really ramping up. At some sites, where strawberries and cherries have been harvested and there are no other berry crops on the farm, numbers have increased to over 1,000 per trap. To me this means that SWD has competed at least one generation at the end of harvest for these fruit crops and is now moving to other susceptible crops.

WE have been rearing SWD from fruit collected weekly at some sites. For the first time we have reared SWD from blueberries (collected July 31) and day neutral strawberries (collected July 28). Growers have reported signs of SWD damage in their commercial blueberry crops for the first time this season. From our samples we know that SWD has been present in wild hosts since July 11.

All growers with susceptible fruit should be actively managing SWD, using all of the following strategies:

  • Weekly insecticide applications with a registered product.
  • Frequent and thorough harvest of all ripe fruit in the field. This means going over raspberries daily except for days missed due to pesticide application, strawberries every 2-3 days and blueberries as often as possible.
  • Immediate cooling of harvested product.

A few more tips: Malathion is an effective product for SWD but residual control drops quickly, especially after rain. Refer to the July 16, 2014 Hort Matters article "Rainfastness of insecticides on fruit" for more information. Delegate and, for organic growers, Entrust, are excellent options for SWD now that the pressure is high.

Insecticides for SWD work because they are killing adult flies in your field. The adults are killed when they contact treated fruit and foliage in your field. Do not spray wild hosts or forest edges.

You can use salt tests to check for the presence of larvae in harvested fruit. These tests provide important follow-up information on the effectiveness of your management program.

How can you help: your feedback is needed. Please help us assess the economic cost of SWD to your business by sharing your notes on crop losses and extra expenses to manage SWD. Please send comments to pam.fisher@ontario.ca .

August 5 - Spotted wing drosophila (SWD) are being trapped at more locations and in higher numbers. This trend is also occurring in the northeastern US and in southern Quebec. We are finding higher numbers of SWD in traps located in raspberries compared to those in blueberries right now, but both are on the rise. To date, we have trapped SWD in the following counties: Elgin, Essex, Huron, Kent, Oxford, Middlesex, Norfolk, Brant, Haldimand, Niagara, Welland, Halton, Hamilton-Wentworth, York, Durham, Northumberland, Prince Edward, Frontenac and Stormont, Dundas and Glengarry.

All growers in southern Ontario should be taking steps to protect raspberries and blueberries from SWD. This means early, frequent and thorough harvest, immediate cooling of harvested product, and weekly application of insecticides. Early fruit from fall-bearing raspberries should be harvested, even though the harvestable quantities may be small. Instruct workers to remove unmarketable fruit from the field during harvest. Spray coverage is very important in order to prevent SWD buildup in the middle of the crop canopy. Rotate insecticide families where possible to prevent the development of resistance to any single product. Do not spray wild hosts, which are an important refuge for pollinators and other beneficial insects.

Our survey is limited in terms of sites and traps in some parts of Ontario, particularly in eastern and northern berry production areas; we do not have enough information to recommend regional spraying. Growers in eastern and northern Ontario should be on the lookout for signs of SWD and taking steps to minimize damage to berry crops as they mature.

SWD has been reared from wild hosts (honeysuckle, wild black raspberries and wild red raspberries) and crops (raspberries, greenhouse raspberries, sweet cherries and haskcaps). It can take a week or two for SWD to complete their development (egg-larva-pupa-new adult), so new adults emerging from wild fruits or crops were laid much earlier. For example, black raspberries collected July 11 had spotted wing emerge July 21, wild raspberries collected July 14 had spotted wing emerge July 24, and sweet cherries collected July 22 had SWD emerge July 29. The emergence trend seems to be 7-10 days post emergence. You can use salt tests to check for the presence of larvae in harvested fruit. These tests provide important follow-up information on the effectiveness of your management program.

For more information, check out webpages regularly: www.ontario.ca/spottedwing

July 31 - Since last week's update we have trapped SWD at more locations and in higher numbers. Nearby in New York and Pennsylvania and southern Quebec, first SWD trap captures have been reported and over the past week the numbers are climbing. SWD is definitely here and already on the increase.

This past week in Ontario we have trapped SWD in the following counties: Essex, Kent, Oxford, Middlesex, Norfolk, Brant, Haldimand, Niagara, Welland, Halton, Hamilton-Wentworth, Durham and Northumberland. All growers in southern Ontario, around Toronto and East Central Ontario should be taking steps to protect raspberries and blueberries from SWD. This means early, frequent and thorough harvest, immediate cooling of harvested product, and weekly application of insecticides. Growers in eastern and northern Ontario should be on the lookout for signs of SWD and taking steps to minimize damage to berry crops as they mature. Although insecticides can probably be delayed in these areas, you should have all the other measures in place.

Spray coverage is very important in order to prevent SWD buildup in the middle of the crop canopy. Rotate insecticide families where possible to prevent the development of resistance to any single product. Do not spray wild hosts, which are an important refuge for pollinators and other beneficial insects.

Update at www.ontario.ca/spottedwing and twitter @fisherpam, #ontag

July 18 - Additional trap captures include Kent, Elgin, and Middlesex counties. In addition we are catching higher numbers than normal for our first week of captures. All growers in southern Ontario and around Toronto should be taking steps to protect raspberries and blueberries from SWD. Updates at www.ontario.ca/spottedwing and twitter @fisherpam, #ontag

Week of July 7, 2014

Total SWD trapped this week 4
Total # positive sites this week 1
# SWD/positive trap 1

Week of July 14, 2014

Total SWD trapped this week 230
Total # positive sites this week 15
# SWD/positive trap 9.58

July 16 - Since last week's update we have trapped SWD at more locations and in higher numbers. Nearby in New York and Pennsylvania and southern Quebec, first SWD trap captures have been reported this past week. SWD is definitely here and already on the increase.

So far in Ontario we have recently trapped SWD in the following counties: Essex, Norfolk, Brant, Haldimand, Niagara, Halton, Hamilton-Wentworth. All growers in southern Ontario and Toronto region should be taking steps to protect raspberries and blueberries from SWD. This means early, frequent and thorough harvest, immediate cooling of harvested product, and weekly application of insecticides. Growers in eastern and northern Ontario should be on the lookout for signs of SWD and taking steps to minimize damage to berry crops as they mature. Although insecticides can be delayed in these areas, you should have all the other measures in place.

Spray coverage is very important in order to prevent SWD buildup in the middle of the crop canopy. Rotate insecticide families where possible to prevent the development of resistance to any single product. Do not spray wild hosts, which are an important refuge for pollinators and other beneficial insects.

2014 SWD trap captures in Ontario
Date collected County Crop Bait* Male Female Total SWD
June 3 Durham region strawberries before harvest ACV
0
1
1
July 8 Essex wild host near a conservation area ACV + yeast
1
0
1
July 9 Norfolk in a wooded area with lots of wild brambles ACV + yeast
0
1
1
July 10 Brant hedgerow near strawberries ACV + yeast
0
1
1
July 10 Essex peaches ACV
1
0
0
July 14 Haldimand wild hosts, swampy area ACV + yeast
3
15
18
July 14 Haldimand blueberries ACV
0
1
1
July 14 Haldimand greenhouse berries ACV
0
5
5
July 14 Haldimand raspberries ACV + yeast
1
5
6
July 14 Halton wild hosts ACV
1
0
1
July 14 Hamilton-Wentworth strawberry ACV
1
1
2
July 14 Niagara hedgerow between strawberry/cherry ACV plus yeast
0
2
2
July 15 Norfolk wild hosts ACV
0
1
1
July 15 Norfolk summer rasp ACV
0
3
3
July 15 Norfolk wild hosts ACV+yeast
1
3
4
July 15 Norfolk summer raspberry ACV
4
5
9

July 10 - An SWD male fly was captured this week, in southwestern Ontario. The trap was in a wild host in Essex county, in an apple cider vinegar (ACV) plus yeast- baited trap collected July 8, 2014.

Also, an SWD female fly was trapped this week in Norfolk country, from an ACV plus yeast-baited trap collected July 9, in a wooded area with lots of wild brambles.

These are the second and third reports of SWD in Ontario this year. As reported earlier, the first fly was collected east of Toronto in Durham region, from a non-fruiting strawberry field, in an ACV trap collected June 3.

Based on these reports, growers in SW Ontario should be on the lookout for SWD damage in raspberries, and cherries. Risk will increase as SWD moves from wild hosts into crops. Insecticide programs and other management practices should be in place to control SWD in raspberries as well as blueberries and other berry crops as they ripen. June-bearing strawberries are close to the end of harvest and do not require insecticides at this time. Prompt renovation could help minimize early populations of SWD in strawberries.

WE are still in the midst of processing our samples this week, so expect more updates in the future. Updates are posted weekly at www.ontario.ca/spottedwing

Thanks to everyone who is collecting traps for us and A BIG THANK YOU to the OMAFRA students and Karen Heal who are patiently processing samples.

July 4 - NO SWD trap captures have been reported in Ontario since the single adult female trapped in early June.

In Michigan, SWD has been trapped in low numbers in SW Michigan for the past two weeks. There is also a recent report of a single SWD fly trapped in Connecticut. WE think that crop and pest development in southern Ontario are a week to 10 days later than SW Michigan.

Typically, in Ontario, we trap the first SWD near the middle or end of raspberry harvest. Wild raspberries and mulberries are ripening now and we are monitoring fruit for signs of SWD infestations. We expect to trap our first SWD in the next couple of weeks.

  • Strawberry growers - be vigilant for overly soft, juicy fruit. SWD is not usually a problem on June bearing strawberries, but it is possible that they can build up in low numbers on late strawberry varieties.
  • Raspberry growers - harvest fruit early and often, collecting all ripe fruit from the field. Prepare to apply an insecticide at the first reports of SWD trapped in your region.
  • Blueberry growers - plan to apply insecticides when SWD is first reported and when blueberries just start to ripen. Note - the registration for Ripcord has recently been withdrawn on blueberries.
  • Fruit monitoring- WE are learning that monitoring fruit for SWD is more effective than trapping. Collect the materials you need for salt water tests - and plan to do these every few days on a sample of your crop. Prepare a salt water solution if 1 cup salt to 16 cups water. Place sound, marketable fruit in a dark shallow pan, cover with salt water solution, and gently mash the fruit. If SWD larvae are present you will see them in a few minutes, writhing in the solution. They are approx. 1- 3 mm in length.

For more information on SWD see:

June 27:  Although we have not trapped any more SWD since our single first trap capture June 3, there have been several reports of SWD in SW Michigan the week of June 15. This is two weeks later than last year for SW Michigan. We expect to find SWD in the next couple of weeks. The first SWD trapped last year in Ontario was in traps picked up July 6. 

Raspberry and blueberry growers should be ready to control SWD when they are trapped in our area. Make sure you have a plan in place for SWD which include frequent harvest, immediate cooling of fruit after harvest, a way to dispose of waste fruit (deep burial, or seal it up in bags) and insecticides on hand to treat when necessary.

Attention blueberry growers: The Pest Management Regulatory Agency has revoked the emergency use registration of Ripcord for SWD control on bushberries. DO NOT use Ripcord on blueberries, elderberries, sea buckthorn, saskatoon berries. etc. On raspberries and other caneberries, as well as strawberries, you can use Ripcord once, at 150 g/ha for suppression of SWD with a 2-day preharvest interval.

See www.ontario.ca/spottedwing for weekly updates on SWD activity in Ontario

June 13 - A team of OMAF staff and students together with 12 scouts and consultants from agribusiness and research , are monitoring for SWD in Ontario in 2014. We are planning to have apple cider vinegar traps set up at 50 key locations between Essex , Ottawa, Niagara, Georgian Bay and New Liskeard. Thanks to the Ontario Berry Growers Association and OFIP 2 funding we have a student placed in eastern Ontario to focus on SWD and have hired an assistant in Guelph to help process trap contents.

We have trapped SWD in 1 location. This was an early trap capture (June 3) of one female fly in a strawberry field east of Toronto. We have not caught SWD at this site since then and do not think that fruit is at risk at this time. Our neighbours in New York and Michigan are not reporting SWD either.

Growers and consultants who are who are monitoring for SWD themselves should have early trap captures verified - we are happy to do that for you. Remember that traps may not be sensitive enough to catch the first SWD on your farm - use regional counts (combined from several locations in a region) to make your spray decisions.


For more information:
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E-mail: ag.info.omafra@ontario.ca