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A natural enemy of invasive berry-eating flies found in the United States

The parasitoid wasp, Ganaspis brasiliensis, is native to South Korea but was first discovered in the United States. Here, a bee lays an egg on a blueberry Drosophila larva.Credits: Kent Daane, University of California, Riverside

The parasitoid wasp, a natural enemy of flies known as the spotted winged Drosophila, can be a good friend for growers. Researchers at Washington State University recently confirmed the discovery of a potentially beneficial bee for the first time in the United States.


Drosophila causes great damage to some Washington crops, especially sweet cherries and berries. Flies that lay eggs on flies can be a means of controlling the spread of flies.

“This is a really positive step for the cherry and berry industry,” said Elizabeth Beer, a professor of insects at WSU. “Hopefully this speeds up the timeline to get biological control of the spotted winged Drosophila.”

Beer and her team discovered a parasitoid called Ganaspis brasiliensis in a wild blackberry patch less than a mile from the Canadian border near Lynden, Washington, in September this year. A small bee was discovered in 2019 in western British Columbia. A Canadian colleague, Paul Abram, asked Beer to monitor cross-border bees and provided tips on where to find them.

Another predatory parasitoid of Drosophila pests, Leptopilina japonica, was also discovered by Chris Looney of the Washington State Agricultural Service in British Columbia in 2019 and Washington in 2020. However, new parasitoids native to South Korea have the great advantage of specificity.

“Ganaspice is very host-specific. It really likes to attack spotted Drosophila larvae and generally doesn’t care about other species,” said Wenati’s WSU Tree Fruit Research and Expansion. Center-based beer said.

Invasive Drosophila not only bite the outside, but also sneak into raspberries and cherries, ruining the whole and damaging the fruit. That’s where parasitoids come in.

A natural enemy of invasive berry-eating flies found in the United States – WSU Insider

Leptopilina japonica (left) is another parasitoid of the invasive and damaging speckled Drosophila (right). Credits: Warren Wong, Agassiz R & D Center

Beer said he could see small adult parasitoids flying around the fruit infested with Drosophila. The female Gana spis then lays eggs in the Drosophila larvae. Small parasitoids occur inside Drosophila larvae and kill them in the process.

“It’s a bit like a movie alien,” Beer said. “It’s unpleasant to think in sci-fi movie terms, but it’s really effective in killing Drosophila with speckled wings.”

Ganaspis parasitoids have recently been bred for biological control by the US Department of Agriculture Animal and Plant Health Inspection Service and approved for distribution throughout the United States.

To do that, entomologists went to the spotted winged Drosophila hometown, found Gana Spis, and regained some samples. Important quarantine investigations have shown that it is safe to spread here to fight Drosophila.

In the process, Ganaspis has found its own way to North America and is expanding without help. Once an invasive species is found to be inhabited in a state, USDA does not regulate its distribution around the state, facilitating the process.

“It’s kind of the best of both worlds,” Beer said. “It’s great to have a lot of research showing that Ganaspis is very host-specific and can be safely disseminated, but there are benefits to being found in nature.”

This is the third exotic species that Beer and her lab have discovered in the last few years. They found a parasitoid of the apple scale insect, a pest of the apple industry, and a samurai bee.

“I didn’t expect this. It’s not the main focus of our lab,” Birth said. “We came across them by chance as part of our research on various pests.”


Researchers have identified successful biological control of destructive fruit flies


Quote: The natural enemy of invasive berry-eating flies found in the United States (November 18, 2021) is https: //phys.org/news/2021-11-natural-enemy-filtration-berry-eating.html Obtained from November 18, 2021.

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A natural enemy of invasive berry-eating flies found in the United States

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