A reminder: SWD treatments may flare spider mites

Remember when treating for spotted wing drosophila (SWD), some recommended materials may also flare spider mites.  Information on how to scout and what do here.

More information
What to watch for: Broad spectrum insecticide can flare mites - Strawberry Growers Information Portal

More thoughts on SWD trapping for 2013: How many traps should growers use?

After hearing several permutations on a similar question this week, namely "how many spotted wing drosophila (SWD) traps do I need to use?", I posted this information on the Strawberry Growers Information Portal.

More information
More on spotted wing drosophila monitoring: How many traps should growers use? - Strawberry Growers Information Portal

Spotted wing drosophila monitoring recommendations for 2013

Spotted wing drosophila traps in strawberry plots at the Horticultural Crops Research Station, Clayton, NC. Photo: HJB

Strawberries are just beginning to ripen in central North Carolina, so last week, we placed spotted wing drosophila (SWD, Drosophila suzukii) traps in our research plots at the Horticultural Crops Research Station in Clayton, NC.  Eagle eyed observers will noticed some differences in the traps in the photo above and those we placed in our SWD plots a few years ago.

Shading traps placed in strawberries

What's easily visible above is that our traps have "hats".  We added these hats because work from other labs suggested that SWD like shade and that leaving traps uncovered in strawberry plantings may catch fewer flies.  In a multistate comparison of SWD traps conducted in 2011, a trap with a "hat", referred to as the Haviland trap, caught more flies than other trap types in a range of different crops.  Hats are likely not necessarily in crops with shaded areas or where traps can be hung directly from host plants, like blueberries, cherries, and caneberries.

A Haviland-type SWD trap with a "hat".  In this case, the hat is meant to keep rain out. The Haviland trap performed well in a comparison of SWD traps during 2011.Photo: HJB

Bait recommendations

In previous years, we have used apple cider vinegar (ACV) as the primary bait in our SWD traps and for the SWD*VMN because early experiences suggested that it was easier to work with compared to a yeast & sugar slurry (the other bait we tested).  However, these early experiences were based on changing the baits less frequently than every week.  When baits are changed weekly, yeast & sugar lures appear to catch more flies and may catch flies earlier than ACV.  Therefore, for 2013, we're suggesting that SWD trappers consider using yeast & sugar lures rather than ACV.

In order to make the yeast & sugar bait, follow the steps below:

Ingredients for yeast & sugar slurry: yeast & sugar! Photo: HJB

1. Collect the bait ingredients, active yeast and plain sugar.

2. Combine 4 Tbsp sugar with 2 Tbsp yeast.

3. Add 32 fl oz of water to the dry ingredients and stir till the mixture is suspended. Do not store premixed bait in a sealed container.  It is actively fermenting (which is what attracts flies) and can explode.  It's easiest to mix bait as it's needed rather than premixing.

4. Fill traps with 150 ml of bait (or just over 5 fl oz) each.  Traps should be check and baits changed weekly.  The odors associated with these non preserved baits change over time, and after one week, they are likely less attractive to SWD.

A few other helpful hits for using yeast traps:

• Many other insects find fermenting yeasts attractive. Traps should have small entry holes, no more than 3/16 large.  Otherwise, larger insects such as beetles, filth flies, and moths will clog traps.
• Trap contents can be poured into a container for transport back to the office or lab rather than counted in the field.
• Do not discard used bait in the field.  We do not want to make our fields any more attractive to SWD than they already are!
• Kitchen sieves can be used to filter flies, but flies in yeast baits might need be rinsed after filtering to see wings, legs, and ovipositors (key ID characteristics) clearly. 

It's very likely that our bait recommendations will change for next year, based on experiments that are planned or already underway. SWD is an invasive species, meaning it's new to North Carolina, and many other areas. Therefore, many of our monitoring and management recommendations are subject to change.  We are all learning a lot of new information, as quickly as we can!

For the time being, we have not changed our trap recommendations. We are still suggesting using 32 oz plastic containers for 2013, although this recommendation is also subject to change, especially if commercially available traps become available that out perform homemade traps.

More information
Plan to monitor insects in 2013 - NC Small Fruit & Specialty Crop IPM

The future of the SWD*VMN for 2013 and beyond

Male (right) and female (left) spotted wing drosophila on a raspberry at the Upper Mountain Research Station, Laurel Springs, NC. Photo: HJB

For the last three years, we have coordinated the Spotted Wing Drosophila Volunteer Monitoring Network (SWD*VMN).  The goals of the SWD*VMN were:

1. To detect the movement of spotted wing drosophila (SWD) if or when it spread throughout the eastern United States
We began the SWD*VMN in 2010, when SWD had only been detected in Florida in the eastern US. The SWD*VMN facilitated the first detections of SWD in South Carolina, North Carolina, Tennessee, Virginia, Arkansas, Louisiana, West Virginia, and Maryland.

2. To determine when during the year SWD are active and relative population densities throughout the year
SWD have been detected earlier each year in states where the SWD*VMN has been active.  In 2012 and 2013, some locations in the southeast caught flies throughout the entire winter. Peaks in trap captures in NC appear to occur in mid summer (July) and fall (after September), with fall populations appearing the largest.  However, these trap capture peaks are subject to interpretation because the traps and baits we use are likely not as attractive to SWD adults as fruit. 

Dates of first trap capture for eastern states participating in the SWD*VMN. Table from Burrack, et al. Journal of Integrated Pest Management.

3. To communicate and display information on detections and trap captures with growers and extension personnel
All trap captures from the SWD*VMN are available here (click on a county to link to the sites in that county and then click on site names to view data from that site). Our policy has been to only identify sites to county.

Along the way to accomplishing these goals, we've been able to gather some additional information. During 2010, we compared different lures at SWD*VMN sites and learned that some baits need to be changed more frequently than others. Our relative trap capture numbers have suggested that some crops may either foster lower SWD populations or be less conducive to our trapping methods.  For example, we catch more flies in shady crops such as caneberries and some grapes and fewer flies in crops with open, sunny canopies such as strawberries and blueberries.  Importantly, this does not necessarily mean that we have fewer flies in theses systems.

Where does the SWD*VMN go from here?
We have accomplished the initial goals of the SWD*VMN and reached the end of the funding which supported the large statewide (in NC) and multi state efforts (much thanks to the Southern Region Small Fruits Consortium and the NC Tobacco Trust Fund, Inc. for their support).  We have also produced a journal article article to more widely share our findings from the SWD*VMN.

Moving forward, we will maintain, and improve the SWD*VMN site for use by our lab and partners in other states to collect, store, and display SWD trap capture data. Collaborators in OR, TN, AR, NY, and other states have expressed interest in continuing to use the site.  The improvements on the way for the site include incorporating graphs to display data for each site and, in the more distant future, incorporating degree day models being developed for SWD by folks in the western US.

In our lab, we will be using the SWD*VMN to collect data from our planned 8 to 12 trapping locations throughout the state, most of which will be at NCSU or NCDA & CS Research Stations. However, we will no longer be directly facilitating large scale SWD monitoring through our laboratory.  We've posting lots of "do-it-yourself" SWD monitoring information and will be posting a monitoring update for 2013 later today.  Please feel free to contact us if you have questions about the SWD*VMN.

More information
SWD*VMN at EDDMapS
All SWD*VMN posts at NC Small Fruits & Specialty Crop IPM

What insecticides are acceptable where?

Over the last few days, I have received several questions about spotted wing drosophila (SWD) management.  The most common question from growers, agents, and others has been: What insecticides are acceptable for use on fruit that will be exported to other countries?  A significant amount of the blueberries, blackberries, and raspberries grown in North Carolina are marketed by companies that sell world wide. A lower percentage of the strawberries grown in the states are sold outside NC, but some growers also work with large marketers to sell their strawberries who may sell fruit outside the US.

While we know what insecticides are acceptable for use crops grow in the US (if it's labeled on the crop, it's acceptable for use here), not all the options available for US growers are acceptable for use on products that will be exported.  Pesticide residue tolerances (or maximum residue levels, MRLs) must be established in receiving countries for a material to be acceptable for export to that country.  One tool I use frequently to determine if pesticide residue tolerances have been established in other countries is the MRLDatabase, developed by the USDA Foreign Agricultural Service (FAS).  This large database allows you to search by crops, pesticides, and countries in lots of combinations.  Just like any pesticide use information, material presented in this database is subject to change.  Therefore, I always recommend that growers speak with their marketer before using a new management tool to ensure that it is acceptable for the markets their fruit may be sent.

More information
MRL Database - USDA FAS

NC Commerical Blackberry and Raspberry Growers Association Meeting - February 19

There's still time to register for the NC Commercial Blackberry and Raspberry Grower's Association Meeting in Shelby, NC on February 19th. I will be there to discuss what we learned about spotted wing drosophila in 2012 and where we go from here.  Gina Fernandez, NC State University, caneberry breeder, has posted meeting details on her blog.

More information
NC Commercial Blackberry and Raspberry Growers 6th Annual Meeting - Team Rubus

Spotted wing drosophila confirmed from Indiana and the United Kingdom - Update: SWD also found in Texas and Colorado

States where Drosophila suzukii, also referred to as spotted wing drosophila, has been detected in the continental United States. Adapted from Burrack, et al. 2012. Journal of Integrated Pest Management.

Spotted wing drosophila (SWD) was confirmed in Indiana during October 2012, bringing the total number of states with confirmed populations of SWD to 33.

SWD was also detected in United Kingdom in September 2012, which brings the number of countries (including the US, Canada, and Mexico) where SWD has been detected outside of its presumed native range of eastern Asia to at least nine.

Update, March 7, 2013
While reviewing the National Agricultural Pest Information System's (NAPIS) Pest Tracker records for spotted wing drosophila in preparation for an upcoming presentation, I noticed two additional state level detections for 2012 that I had previous missed, Texas and Colorado.  These detections bring the total number of states where SWD has been detected to 35 since 2008.

More information
First find of spotted wing drosophila in Indiana - Purdue Plant & Pest Diagnostic Laboratory
Strawberry alert: The 2mm fly that could decimate Brittan's fruit industry - The Daily Mail
Drosophila suzukii - European Plant Protection Organization (EPPO) Factsheet

SWD*VMN article published in Journal of Integrated Pest Management

A summary of our three-year multistate Spotted Wing Drosophila Volunteer Monitoring Network (SWD*VMN) has recently been published in the Journal of Integrated Pest Management.  The Journal of IPM is open source, and you can access the article here. You can find SWD*VMN from trap captures from 2010 through present here.

Spotted wing drosophila biology and mangament in blueberries

Our final spotted wing drosophila (SWD) factsheet for the year focuses on blueberries.  Please note, factsheets are shared via Google Documents, which is great for quickly and easily posting files but does sacrifice image quality.  If you would like a printer quality digital copy of this factsheet. Please email me.

You can find the first factsheet on SWD biology and management in North Carolina caneberries here, the second on post harvest SWD significance and sampling here, the third on SWD in strawberries here, and the fourth for home gardeners here.

Spotted wing drosophila biology and management in home gardens

The fourth in our series of spotted wing drosophila (SWD) factsheets focuses on home gardeners.  Please note, factsheets are shared via Google Documents, which is great for quickly and easily posting files but does sacrifice image quality.  If you would like a printer quality digital copy of this factsheet. Please email me.

You can find the first factsheet on SWD biology and management in North Carolina caneberries here, the second on post harvest SWD significance and sampling here, and the third on SWD in strawberries here.

SWD detections increase

Spotted wing drosophila (SWD) detections in the upper Midwest continue to increase.  SWD adults and larval damage is now confirmed from :
Illinois
Iowa
Minnesota 
Wisconsin

I'll have a detailed update on our SWD research, extension, and education efforts next week.

Spotted wing drosophila detected in Arkansas

On July 9th, Donn Johnson at his team at the University of Arkansas detected the first spotted wing drosophila adults in Arkansas.  You can read about this find here and see the trap capture data at the SWD*VMN.

Spotted wing drosophila biology and management in North Carolina strawberries

The third in my summer series of spotted wing drosophila (SWD) factsheets focuses on strawberries.  Please note, factsheets are shared via Google Documents, which is great for quickly and easily posting files but does sacrifice image quality.  If you would like a printer quality digital copy of this factsheet. Please email me.


You can find the first factsheet on SWD biology and management in North Carolina caneberries here and the second on post harvest SWD significance and sampling here.



This Thursday I will be attending a strawberry field day in Watauga County, NC at a farm that grows day neutral (summer fruiting) strawberries and sharing information from this factsheet as well as results from our spring strawberry SWD management experiments at the Central Crops Research Station. Day neutral strawberries present unique SWD management challenges because they fruit through fall, when the highest SWD populations of the year occur.  You can read more about day neutral strawberries at the North Carolina Strawberry Association's blog.

More information
Strawberry field day - Watauga County Cooperative Extension

Spotted wing drosophila in the city

Spotted wing drosophila mating pair outside a Wake County, NC home.  Photo: Matt Bertone.

Entomologists at the North Carolina Nature Research Center and NC State University are partnering to count the creepy crawlers and unseen critters that live inside our houses, and have found spotted wing drosophila (SWD) during their search.

Led by Michelle Trautwein, Assistant Director of the Biodiversity Laboratory at the Nature Research Center, Arthopods of Our Homes seeks to understand the diversity of insects and other arthropods in homes and how human residents influence their populations.  In the handful of houses the team has sampled so far, they have found over 100 species.  Not necessarily a surprise to us entomologists, who know insects are all around us, but it is exciting to demonstrate such diversity so close to home!

Eagle eyed dipterist Matt Bertone, part of the Arthropods of Your Home team, spotted two mating SWD in the yard of a recently sampled home and collected a few others inside.  The flies inside are particularly interesting, as we suspect that man made structures may help adult flies overwinter because they don't diapause, or hibernate, like many other insects.  Understanding how common SWD is in non agricultural habitats and during what times of year we can find them will help us develop whole-system management tools, not to mention help us understand how significant a concern they may before your backyard garden.

Matt will be record SWD finds as part of the SWD*VMN (Spotted Wing Drosophila Volunteer Monitoring Network).  You can find the record for the first one here.

More information

On location with the Arthropods of Our Homes team - Your Wild Life Blog 

Sign up for Arthropods of Our Homes - Your Wild Life

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Spotted wing drosophila post harvest and larval sampling factsheet

I've completed the second in a series of spotted wing drosophila (SWD) factsheets.  This one addresses post harvest concerns about SWD and summarizes larval sampling methods.  As with much relating to SWD, there is a lot we don't yet know, but this factsheet provides a starting point for those interested in developing a sampling plan for larval SWD.



Please note, factsheets are shared via Google Documents, which is great for quickly and easily posting files but does sacrifice image quality.  If you would like a printer quality digital copy of this factsheet. Please email me.

You can find the first factsheet on SWD biology and management in North Carolina caneberries here.

SWD factsheets for Summer 2012

I have started working on a series of updated spotted wing drosophila (SWD) factheets for Summer 2012, the first of which is a general factsheet for caneberry (blackberry and raspberry) growers.
Look for more updated factsheets for strawberries, blueberries, grapes, homeowners, and on trapping and larval sampling soon.

Reminder: blackberry field tour this Thursday!

Green June beetle on ripe blackberries at the Lower Coastal Plain Research Station, Kinston, NC during a research trial in 2009. Photo: HJB

This Thursday I will be in Henderson County for a blackberry twilight tour organized by the Henderson County Cooperative Extension office; contact them for location and schedule information. I have already had two calls this week with questions about spotted wing drosophila (SWD) and blackberries, so I will be focusing on that topic and will also touch on thrips and cane borers.

Results for multi state spotted wing drosophila project: what's next for eFLY

Female (left) and male (right) spotted wing drosophila on a raspberry at the Upper Mountain Research Station near Laurel Springs, NC. Photo: HJB

Last fall I solicited help from the readers of this blog and from small fruit growers, consumers, and researchers from throughout the eastern US to rank spotted wing drosophila (SWD) research and extension needs.  You responded in force with over 300 responses to our online and in person surveys.  A group of researchers and extension folks (include myself) used these responses to craft a multi state project, including cooperators from Georgia, Michigan, New Jersey, New York, and North Carolina with connections to projects in many other states, which we submitted to the USDA Specialty Crop Research Initiative Program. We entitled our project eFLY. There is ongoing research activity in the western US on SWD, including the SWD*IPM group coordinated through Oregon State University, but we felt strongly that environmental differences in the eastern US presented very different management challenges for SWD and regionally appropriate research was crucial. This conclusion was borne out in 2011 when monitoring tools and management strategies developed in the western US did not prove effective in the southeast US and continues to be the case in 2012 as we encounter another difficult SWD management season.

Unfortunately, we recently received word last week that our project was not selected for funding.  I don't often share the results of grants with the readers of this blog, but the feedback and participation we received from small fruit stakeholders throughout the eastern US to our request for help was so fantastic that I felt I should share the ultimate outcome with you as well.  Reviewers of our proposal cited our strong stakeholder engagement as a strength of the proposal, which is in no small part thanks to the responses we received from you to our survey.  

What does this mean for SWD research in the eastern US moving forward? 

The goal of developing a multi state project was to answer questions about SWD management and biology throughout the eastern US and to develop near-term implementable SWD management programs.  A project of this scope will be highly unlikely without funding.  A number of the scientists cooperating on this project have some regional or state support to conduct work on SWD. 

Our lab has funds from North Carolina and from the NC Blueberry Council which will support some of our work for this year and part of next summer.  The SWD*VMN will continue at least through 2012, and we hope to continue into 2013.  Beyond this, however, funding is unclear.  We will likely be seeking your feedback again for future multi state projects as well as reaching out to our state and local grower communities to understand their management needs and for continued and further support.  

Please do not hesitate to contact me for more information on SWD in the southeast.

Do it yourself: An update on distinguishing SWD larvae from other insects in strawberries

Early this spring, I wrote a post discussing how to distinguish spotted wing drosophila (SWD) larvae from other internally feed insects.  That post was focused primarily on blueberries.  This spring and early summer, however, I received several calls about SWD in strawberries, and they appeared in our research plots for the first time.

Fortunately, the majority of grower calls I received about larvae in strawberries ended up being sap beetle larvae rather than SWD larvae.  Sap beetles or picnic beetles are actually a complex of beetle pests which include at least three species in North Carolina (Carpophilus lugubris, Stelidota geminata, Glischrochilus quadrisignatus, and others) and are attracted to rotting, not sound fruit.  If rotting fruit are present near sound fruit, as can commonly happen when you-pickers aren't thorough or rain prevents picking, sap beetle adults and larvae can also attack sound, otherwise marketable fruit.

While sap beetle larvae are also not desirable in strawberries, they are more easily controlled than SWD.  Good sanitation, meaning removal of overripe or rotting fruit, is usually enough to keep sap beetle populations in check.

How, then, can you distinguish between sap beetle larvae and SWD?

Host fruit
Sap beetles will first attack overripe, rotting, or otherwise damaged fruit.  SWD will be found in fruit that appears otherwise marketable until cut open.  As SWD grow older, fruit condition may deteriorate, but fly larvae found in sound fruit are more likely to be SWD than those found in rotting fruit.

Size
Young sap beetle larvae may be similar in size to large SWD larvae, but in general they will be larger than SWD larvae.  Size on its own is not a good determinant, but it can be a good initial indicator.

Sap beetle larva on knife blade. Photo from a commerical strawberry farm in eastern NC, 2012.

 Appearance
SWD larvae lack legs, have no distinct head, lack hairs or bristles, and are tapered on both ends (see here for more images).  Sap beetle larvae have distinctive head capsules, three pairs of legs, and bristles along their bodies.  Adult sap beetles may also be present along with larvae.

Sap beetle larva. Note the three pairs of legs, the distinctive brown to black head capsule and the bristles along the body.  Sap beetle larvae will be mostly white or cream colored and lack patterns on their body. Photo from a commerical strawberry farm in eastern NC, 2012.

Two spotted wing drosophils larvae (center) inside a day neutral strawberry, Upper Mountain Research Station, October 2011. Photo: HJB

What other insects might be present inside strawberries?
Corn earworm (Helicoverpa zea) are occasional pests of strawberries, and the larvae can tunnel into berries.  Corn earworms are caterpillars, which means they have a distinctive head capsule and three pairs of front legs like sap beetle larvae, but they also have short, grippy prolegs along their abdomen and have a pattern of stripes along their body (although their appearance can be highly variable as larvae age).

Corn earworm larvae feeding on strawberries. Photo via UC IPM.

What should growers and homeowners who find SWD do?

I am getting reports of spotted wing drosophila SWD larval activity in some southeastern locations over the past two weeks, and we have observed SWD infestation in some of our research station plots in North Carolina.  Infestations in my plots are a good thing, because it allows us to study SWD here and provide you with up to date information, but infestations in grower fields are another matter. We have been catching adult SWD since January in North Carolina, but these are the earliest larval infestations we have recorded in the state.  This early activity has prompted several questions about what growers or homeowners should do if they find SWD infested fruit.  Here's a quick summary of the four key steps you should take in the event of SWD infestation:

1. Remove all ripe and ripening fruit and destroy it (by freezing, "baking" in the sun inside a clear plastic bag for a few days, or removing from the site).  Eggs or larvae may be present in otherwise sound appearing fruit. Leaving this fruit means that potentially infested fruit is present and could be harvested.

2. Begin an aggressive (once per week if it does not rain, reapplication in the event of rain) spray program.  Rotating between at least two modes of action will reduce the likelihood of resistance development.  See here for information about the probably efficacy of registered insecticides in southeastern small fruit crops.  Because these efficacy ratings are based on work done largely in the western US, where environmental conditions differ, they are not set in stone.  We are running several efficacy trials as I type and hope to have NC specific data by mid summer. 

3. Practice excellent sanitation.  Remove all ripe fruit and sell or destroy it.  Do not discard culls in the field, and clean up after rain and u-pickers. Unpicked fruit is a reservoir for SWD larvae.

4. Sample fruit regularly and consider trapping flies.  Traps tell you SWD presence or absence and are not perfect, but they are helpful.  Place traps in strawberry rows, near fruit for the best chance of catching flies.  Sample fruit each harvest by either cutting them open and looking for larvae, crushing them in salt water (1/4 cup salt per gallon), or freezing them.  Salt water and freezing will cause larvae to exit fruit.  Sample at least 30 berries per field.  See here and here for trapping information and here for larval sampling information.

All growers are strongly encouraged to monitor for SWD adults before larvae are found.  If adults are present and fruit are ripe, pesticide treatments are recommended through the end of harvest.  We hope that this strategy will prevent larvae from showing in fruit and triggering the actions listed here.

Update, June 22, 2012
I am aware that homeowners may be not be able or may prefer not to use insecticides on fruit in the gardens are yard.  Unfortunately, sanitation alone will not eliminate and SWD population.  However, if you can pick your fruit a bit earlier or a bit less ripe, it will be exposed to SWD for less time and will perhaps be at a lower risk of infestation.  It's also important to note that while SWD larvae cause fruit to decay quicker and are unpalatable if present in fruit, they are not poisonous or parasitic.  If you have inadvertently consumed fruit from your home garden that SWD larvae have been present in, they do not pose a heath risk.

Update, August 7, 2012
I have been reading LOTS of scientific papers about SWD in the last week.  A couple of Japanese references suggest that mesh cages or bags (specifically 0.98mm mesh) prevented SWD infestation in blueberries without impacting plant growth.  We use mesh bags a lot to either keep insects we are studying in or to keep insects we don't want out.

We have used mesh bags in blackberries to exclude thrips from developing fruit in order to determine if they impact fruit development.  They don't appear to.

This strategy is worth a shot for homeowners who can tolerate the sight of bags on their plants.  In order to exclude SWD, cages should be placed before fruit begins to change color and tightly sealed at the bottom.  We'll often place a piece of quilting foam between the cage and the stem of the plant to allow us to tightly tie the cage shut (with a zip tie or twine) but protect the stem from damage.  Cages should stay in place until you harvest your fruit.  We use organdy mesh from fabric store and sew our cages to size, but paint strainers also work in a pinch.  I plan to try this method with my backyard blueberries, blackberries, and figs next year and will be interested to hear if others also give it a shot.