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University of California Agriculture and Natural Resources Agriculture and Natural Resources Blogs
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Update on the Cherry Vinegar Fly, Drosophila suzukii , Now Known as the Spotted Wing Drosophila
Published on: July 9, 2009
This a brief summary of the information presented at yesterday’s meeting in Stockton about the cherry vinegar fly, now known as the spotted wing drosophila (SWD), Drosophila suzukii. The purpose of the meeting was to update researchers, growers and industry personnel on the status of this pest.
 
Spotted wing drosophila has now been found in cherries, raspberries, blackberries, blueberries, and strawberries in California. It has been found in many (I think the number was 21) counties across California, as well as several other states. However, in the case of detections from other states, it has not yet been determined whether the detections come from fruit grown in those states or simply were fruit from infested areas of California incidentally brought back into California. 
 
Of the 3000 species of Drosophila commonly known as vinegar flies only two have been found to be harmful to crops, of which the spotted wing drosophila is one.   The female has a serrated ovipositor, meaning she can penetrate the skin of most thin skinned fruit. In the lab it takes from 2-3 minutes to oviposit, and this oviposition is not necessarily successful each time. Nevertheless, in an experiment done by Artyom Kopp from UC Davis, three females put in a test tube with a Thompson seedless grape had several dozen eggs laid overnight. A female will lay 2-3 eggs per fruit, and will lay around 350 eggs in her lifetime. The life cycle in the laboratory, from egg to egg laying female, is 12 to 15 days at 65o F. The egg and larvae develop inside of the fruit, and while experts at the meeting said that pupation takes place inside of the fruit also, I have taken many samples of strawberry and raspberry and they are always exiting to pupate.
 
It is thought that SWD will have ten generations per year, and probably 3 generations in one crop of cherries. Thus, the population growth potential of this pest is tremendous. They are most active at 68o F and activity becomes reduced at temperatures above 86o F. Above 86o F, males become sterile. Eggs, larvae and adults (probably pupae are not far behind) die at temperatures below freezing, but this does not necessarily mean a whole population will be eradicated at lower temperatures, since D. suzukii is firmly established on the island of Hokkaido in Japan, where winters are quite cold. Additionally, vinegar flies in general are very sensitive to dessication, and will die within 24 hours in the absence of water.
 
On the regulatory side, we were informed that neither the CDFA nor the USDA are recommending any regulatory action (such as a quarantine) at this time. On a conference call regarding SWD with USDA and the National Plant Board, no other states made any commitment to conduct a survey for this fly. While the state of Oregon may have some concerns with this pest, they have to prove an absence of it before any action can be taken.
 
Spotted wing drosophila adults on raspberry.
Photo Courtesy Ed Show
Spotted wing drosophila adults on raspberry.

Tags: cherry vinegar fly (1), drosophila suzukii (4), spotted wing drosophila (15)
Comments: 19
Confirm and Intrepid as Control Agents for Leafrollers including Light Brown Apple Moth
Published on: July 4, 2009

 

 

Under current regulatory pressure for eradication of light brown apple moth, local caneberry growers have been striving to maximize leafroller control to the greatest extent possible. The pesticide Confirm 2F, which has excellent efficacy on leafrollers while having little activity on non-lepidopterous insects, has become a point of interest. It is worth the while to discuss the use of this material, along with a comparison to the related, but unregistered in caneberries, Intrepid 2F.
 
It should be emphasized that while Confirm 2F has excellent leafroller control characteristics, the label is restrictive in that the required interval between application and harvest (also known as the “pre-harvest interval” or PHI) in caneberries is 14 days, meaning harvest season applications without the loss of crop are not possible.
 
Additionally, since Confirm 2F needs to be ingested by leafroller larvae to realize the highest efficacy, uniform and thorough coverage in the field is essential. Use of high per acre rates of water carrier, high application pressure and spreader sticker adjuvants are all recommended as a way of increasing the effectiveness of this material.
 

Confirm (tebufenozide) and Intrepid (methoxyfenozide) are chemically similar pesticides and have the same mode of action. Both mimic the action of ecdysone, a hormone involved in initiating molting and metamorphosis. The result of ingestion or contact of either of these materials is a premature acceleration of the molt of the immature stages of target larvae and death a few days later. 

Intrepid can be thought of an upgrade of Confirm, and is generally more efficacious, 
as it has longer residual activity against some pests. In crops where it is currently 
registered, Intrepid has a fairly short pre-harvest interval. For example, the preharvest 
interval for Intrepid is one day in strawberries, versus 14 days for Confirm in caneberries. 
With this in mind, it will be worth pursuing an Intrepid label similar to strawberries in 
caneberries.  Replacing Confirm with Intrepid for most crop uses is a worthy goal. 
 

There are pesticides mentioned for management of leafrollers in this article. Before using any of these products, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.

 
 
Comments: 1
Discussion of Management Approaches for Cherry Vinegar Fly, Drosophila suzukii.
Published on: June 20, 2009

 

The recent infestation of local crops by the cherry vinegar fly, Drosophila suzukii, is serious. Vinegar flies normally are associated with rotting and over-ripe fruit and have not been thought of as being anything beyond a nuisance. However, the cherry vinegar fly is different from other vinegar flies in that lays eggs into fruit which are yet to be harvested. The larvae then feed within the fruit and exit to pupate. The feeding of the larvae, while damaging in itself, also exposes the fruit to fungal and bacterial infection.
To growers, a pest such as the cherry vinegar fly presents several challenges. The first is that three of the four stages of fly development, namely the egg, larva and pupa are generally inaccessible to conventional pest management methods. Secondly, the very high numbers of flies frequently found in production fields and the apparently high breeding potential of the individual female make it very difficult to reduce a population quickly to economically acceptable levels once it is established.
While apparently new to Santa Cruz County and other areas of California, the situation of the cherry vinegar fly is not unique. Serious infestations of fruit flies (not vinegar flies) in Hawai’i, California and Florida have been successfully brought under control by multi-faceted management programs, which can guide us in our approach to managing the cherry vinegar fly.
A successful management program for cherry vinegar fly will quite likely consist of three essential parts:
 
1. Use of attractant bait sprays. Attractant based sprays, such as the GF 120 or NuLure, utilizing environmentally safe toxicants used in low volumes across the production field and border areas can be useful in reducing fly populations while minimizing effects on predators, parasitoids and honeybees. However, since the efficacy of any bait and toxicant decreases over time, these materials need to be re-applied, perhaps at weekly or bi-weekly intervals to be effective.
 
2. Field sanitation. Infested fruit which remains in the field allows eggs and larvae to fully develop and serve as a source of more flies. All infested, ripe fruit should be removed from the field and destroyed, either by burial or disposal in a closed container.
 
3. Looking at other successful programs of fruit or vinegar fly management, it is clear that using the above practices over a wide area was essential. It is important for every grower within a fly infested area to participate, since a single, unmanaged field will serve as a source of infestation to surrounding fields.
Comments: 8
Light brown apple moth in blackberries
Published on: June 4, 2009

The following is in regards to an infestation of light brown apple moth (LBAM) causing economic (approximately 20% or greater loss) damage in blackberries.  This occurred in a single field several weeks ago, and has since been addressed by the grower and regulatory agencies.

This information is being provided in the interest of emphasizing to the grower community that this pest is not only a regulatory problem now, but is capable of becoming an economic problem as well.  It is imperative then that growers undertake appropriate control measures to minimize the chance of infestation.

The pest. Quite likely light brown apple moth, because of the high percentage of positive finds in this blackberry field.
Photo courtesy USDA
The pest. Quite likely light brown apple moth, because of the high percentage of positive finds in this blackberry field.

Leafroller webbing on undeveloped fruit. Bottom fruit is ruined.
Photo courtesy USDA
Leafroller webbing on undeveloped fruit. Bottom fruit is ruined.

Leafroller webbing on mature fruit.
Photo courtesy USDA
Leafroller webbing on mature fruit.

Result of leafroller webbing in between developing fruit. Fruit is malformed and unmarketable.
Photo courtesy USDA
Result of leafroller webbing in between developing fruit. Fruit is malformed and unmarketable.

Webbing plus leafroller on fruit. Fruit would not be marketable, and leafroller larvae has a high probability of ending up in the basket and heading to market.
Photo courtesy USDA
Webbing plus leafroller on fruit. Fruit would not be marketable, and leafroller larvae has a high probability of ending up in the basket and heading to market.

Comments: 4
Drosophila suzukii update
Published on: June 3, 2009

The following refers to trap counts taken on June 2 of Drosophila suzukii, previously (incorrectly) identified in this post as Drosophila biarmipes.

Several raspberry fields have fairly high counts of D. suzukii now.  One in the vicinity of Peckham Rd and another on Riverside Rd have counts in excess of 50 D. suzukii males (identified by the spots on the back of each wing) per trap, numbers which would be consistent with some fruit damage.  Another raspberry planting on Thompson Rd also has seen an increase to 28  male flies found in one trap.  It is recommended in these cases to start a program of control.

Two farms which have been applying GF 120 fruit fly bait since the end of March/ beginning of April have seen sharp reductions in the numbers of D. melanogaster and D. suzukii trapped.  While this is not a controlled study with an untreated check, it does suggest that consistent, weekly applications of GF 120 fruit fly bait are useful in reducing numbers of this pest.

Another point of interest is that one raspberry plantation that had increasing numbers of vinegar flies (both D. melanogaster and D. suzukii) made a series of 3 applications of Entrust (which contains the same active ingredient as GF 120 fruit fly bait) over a two week period to control leaf rollers.   The last trap reading had a single vinegar fly found, again suggesting some effect of this pesticide on the vinegar fly population.  However, this is not a trial with an untreated control, so this evidence should be understood as being anecdotal only.

To date, blackberry fields have had very few flies trapped.

There are pesticides mentioned for management of vinegar flies in this article. Before using any of these products, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.

 

Comments: 0
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