Spotted Wing Drosophila (SWD) Bait Spray

NOP Organic

AKA: vinegar fly, cherry fruit fly, cherry vinegar fly, Drosophila suzukii

Family: Drosophilidae. Subfamily: Drosophilinae. Genus: Drosophila. Tribe: Drosophilini. Author: Matsumura

Experimental SWD bait spray

Attract and Kill Strategy

The SWD is attracted to active yeast, and a fly eating fungus, Beauvaria bassiana, brand name balEnce, has been developed commercially in the US, EPA registered. This is a strain that is specific to flies. It works well against Drosophila. It would be interesting to see if a yeast (live or dried) bait could be made up with the Beauvaria as the active agent in an attract and kill strategy. A spray with the yeast and balEnce could be sprayed in the field on a weekly schedule to suppress the drosophila. Other bait and kill strategies use about 10 gallons spray per acre, with large droplets, widely scattered.

see SWD Integrated control page

US EPA registered 70787-2

CA EPA has not yet approved balEnce registration in CA. Ok to use in OR, WA

Sample material is available for researchers to do trials.

balEnce material info

balEnce label

We at Rincon-Vitova Insectaries are in a position to distribute a bait spray that looks very promising for control of spotted winged drosophila (SWD).

The bait spray with the Beauvaria strain (proprietary name is balEnce) that is specific to flies promises to be a good control option for spotted winged drosophila. The Beauvaria (insect eating fungus) spores should remain 90% viable for a week in the field. They should be viable in a bait spray matrix - the developer is testing a couple formulations. A combination of live yeast, dried yeast, and sugar should be a good bait lasting a few days to a week in the field.

This Beauvaria strain is specific to flies. There should be minimally harmful to beneficials, just the flies that would be attracted to the bait, maybe some decomposer flies, in addition to the SWD. The spores of the fungus have been shown to have 80% activity after 1 month in field conditions.

A small amount, 10 gallons per acre, of material is thought at this time to be an effective rate. One quarter of a 15 ounce bottle of balEnce provides sufficient spores to kill all the SWD in an acre (about $25/acre for active ingredient). One spore lodged in the mouth parts of a fly is enough to kill the fly.

Spraying a small amount of material, there is minimum risk of plant or fruit damage. In cane berries, spray can be directed to parts of plant without fruit. Depending on how far the drosophila fly it may be possible to skip four rows between treated rows.

The materials are low risk, no need to stop field operations, zero REI. Someone with a backpack sprayer can be spraying while others are working in the field. No limit on residues on food. Organic acceptable material.

The bait materials in the spray that are not eaten by the SWD are good food for beneficial insects, such as lacewing, ladybugs, syrphid flies, and spiderlings. Syrphid flies would be attracted to uneaten bait and may be affected by the fungus but unlikely since they are in a different family from the Muscids . The bait formula is similar to Rincon-Vitova's Insect Food that we mix for supplemental food for beneficials.

The recipe that I want to try:

1.5 ounce balEnce

1 ounce live baker's yeast

0.5 pound sugar

0.5 pound dried brewer's yeast

1 gallon water

It should be made up the day before, held in a vented container over night, and sprayed to deliver large droplets that are widely scattered.

The producer of the Beauveria product is as eager as I am to support trials with materials and our expertise.

The product has been under consideration by CA EPA for two years, but not yet approved.

Entomologists have noted that live yeast was attractive to D. suzukii for 3-4 days in a jar.

My conceptual approach follows this reasoning: If the bait is sprayed early in the morning or late in evening, It should be attractive for 3-4 hours until it dries, during which time it should be very attractive to SWD. With dew, irrigation or fog, the sugar and yeast should serve as a humectant, drawing moisture to it. The yeast should start fermenting when the sugar is diluted enough to bring the available water up to a level that it can start growing. At this time it would again be attractive to SWD.

It would be great to have someone make observations with SWD in lab and field and see if it actually works in practice, and the parameters you bring up: longevity, range of insects attracted, range of insects killed.

Many adult flies and parasitic wasps are attracted to sugar sources for energy to move around laying eggs. It could be that SWD would be attracted to just the sugar as an energy source vs the fermenting smell for oviposition. This is the basis of Dows GF-120 NF Naturalyte Fruit Fly Bait Spray. I have seen a note that GF-120 is not considered effective against SWD.

Ken Hagen did a lot of work with sugar/yeast mixes in the late 60's for managing populations of lacewing and ladybugs. At the time the brand name was wheast, yeast grown on whey. Worked good for a while till the dairies changed the process and the product had too much salt to support growth of insects. Now we use dried brewers yeast from corn feed stock that is used to make beer and then alcohol.

Insect Food bulletin

This is like artificial honeydew and attracts aphid predators that come in when a plant is filthy with honeydew. These are lacewing, ladybugs, syrphid flies. Joe Patt, at USDA Weslaco, has been using it to feed spiderlings and they grow well on it, though do best on frozen live yeast.

We use a yeast, soy, milk powder for our adult fly and lacewing food. We use live yeast, bran and milk powder for our maggot food. This is stuff we work with daily. We buy most of these materials by the pallet.

Couple of things we have seen with other flies including fruit flies when we use beauveria. When I talk about the time to get control of 14 days, that is for the population in total as insects infected will die in 2 to 5 days. I am only referring to a situation where the population is out of control when we start, then it takes at least 50 to 75% reduction of female numbers to cut down the egg lay and get control.

In situations where we know the pest is present and have a start time for either emergence or know when it will show up, as long as we start treatments at that time, we never see any population build up, and there fore no catch up in control.

Normally, once infected, females cease to oviposit, as long as this is true with this fly then the length of time from infection to death of 2 to 5 or 3 to 5 days is not important as they are not contributing to potential eggs in the fruit or field.

Our experience with fly control has been poultry and other livestock. We do deal with very high numbers of insects, but are at an advantage because they are confined to a building and attracted to that site for breeding. In poultry, we can gain control post cleanout when fly pressure is at a max. in 21 to 35 days. that is normally in the fall or spring depending on when manure is needed for fields. once control is gained, with the help of good manure management and beneficial insects, most of my clients do not treat for flies all summer. We have consistently given better fly control as a program than any chemical, and at the end of the day for less money than pyrethroid or neo-nic. treatments.

Our fruit fly work has been with D. repleta, they are fairly common in swing farrowing and on occasion poultry. I checked a farm late yesterday and they have 4 rooms that have populations of 40 to 50 flies per sq. ft. of ceiling, all are only 1 week into the cycle ( 21 day cycle) so I will try to treat some of them today or tomorrow with the mixture ron has as well as with the 2 attractants we have to see if there is any difference with this species. Not sure how that will translate, perhaps you could help with that part as I have no experience with your SWD.

I look forward to working with you in some way to see if there is some way to control this pest economically and ecologically.

Ron Whitehurst, PCA

Rincon-Vitova Insectaries, Inc.

www.rinconvitova.com

800-248-2847