The vinegar fly is a new pest of orchard and fruit crops – attacking over 100 different kinds of fruit – including blueberry, cherry, blackberry, and grape
The research says “In studies there, he and his colleagues showed that drosophila flies prefer the taste of a commercial sweetener called “erythritol” over sugar (sucrose) and that this preference can be exploited for control purposes. Erythritol is a naturally occurring sugar alcohol found in fruits such as pears, grapes, and melons. It is commercially produced by fermenting corn starches with a fungus.”
Doses and strengths tested:
“In field tests this past summer, however, spraying blueberry and blackberry plants with erythritol reduced larval numbers by 75 percent, greatly diminishing their potential to damage the fruit.
Sampson says a dosage of 61,000 parts per million (about half a pound per gallon) worked best and probably killed the larvae by drying them out. The fruits, however, were unaffected, he adds.
In related tests, progressively higher doses of erythritol shortened the life span of adult flies and killed them outright at the highest concentrations. But the cost of targeting adult drosophila with the sweetener was about four times that of using it to kill larvae ($452 versus $112 per acre, respectively).”
You can read the research here.
Doug says that sweet traps work on some pests for sure (ever seen how many insects work hummingbird feeders?) and while this is aimed at the commercial grower, home gardeners with this pest could do something similar.