Frequently Asked Questions (2015-2019)

Where did spotted wing drosophila come from?

SWD is believed to be native to eastern Asia and has been detected along the Himalayan Mountains into central Asia. It was first documented as a crop pest in Japan in the early 1900s. See Asplen et al. 2015 for an overview of the history of SWD invasions.

How long has spotted wing drosophila been in the United States?

SWD was detected in Hawaii in 1980 and become very common by the 1990s, however it did not cause any known damage to crops. SWD was first detected in the continental United States in California in 2008 and rapidly spread throughout North America so that by 2012 it had been detected in all areas where host crops are grown. See Asplen et al. 2015 for an overview of the history of SWD invasions.

Does spotted wing drosophila have pheromones?

Spotted wing drosophila and other Drosophila species do not appear to use pheromones as long range attractants, unlike some moths or beetles. Some Drosophila species use a chemical called 11-cis-vaccenyl acetate (cVA) as a short-range attractant. cVA is a male-specific attractant, but spotted wing drosophila does not produce cVA although they may have retained the ability to detect it.

In other words, there are not pheromone-like attractants that we can use in trapping spotted wing drosophila or in mating disruption.

Are there native predators and parasites that feed on spotted wing drosophila?

Yes, there are predators and parasites found naturally in North America that feed on spotted wing drosophila, but they do not kill enough flies to control populations. The greenhouse rove beetle has been demonstrated to feed on larvae within fallen fruit in controlled environments. Parasitoid wasps that attack spotted wing drosophila have been found in both North America and Europe. The species naturally found in Europe and North America are generalists, feeding on many different fly species, and are not present in high enough numbers to control populations. Our project activities include explorations for parasitoids in the native range of spotted wing drosophila, importation of potential beneficial insects to quarantine facilities in the United States to test against SWD, and potential release of promising species after USDA permitting.

Are there non chemical ways to manage spotted wing drosophila?

Yes. Exclusion netting is promising (see January 10, 2017 OREI summary) to reduce risk of SWD damage, particularly in blueberries. In addition, frequent, thorough harvest reduces the amount of time fruit is exposed to egg laying flies. Our project and others are exploring other non chemical tools that will reduce the need for insecticides.