Drosophila gentica, one of two newly-recognized fruit flies in Los Angeles. Photo by Kelsey Bailey, Natural History Museum of Los Angeles County.
A group of researchers from the U.S. and Australia have announced the completely unexpected discovery of two exotic fruit flies in urban Los Angeles in a paper appearing in the journal PLOS ONE. The species were not previously known to exist in the U.S.
Flies in the insect genus Drosophila — commonly known as fruit flies or vinegar flies — are among the world’s most-studied organisms. More than 16,000 research papers were published in the last five years with the word “Drosophila” in the title. Yet we still know little about their natural history, this study shows.
One of the newly-noted species, Drosophila gentica, was the second-most common fruit fly in the Los Angeles survey. This species was described in 1962 based on specimens collected in El Salvador in 1954, the first and last time it was recorded anywhere until now.
“Los Angeles is definitely not the first place I’d have started looking for new specimens of this species,” said David Grimaldi, curator at the American Museum of Natural History in New York, also a co-author on the paper.
The other newly-noted species, Drosophila flavohirta, has its origin in Australia, but has accompanied transplanted eucalyptus from Australia to South Africa and Madagascar. That might also explain its presence in California, given the popularity of eucalyptus trees and shrubs there.
How could these species of one of the world’s most studied organisms have escaped notice for so long in a place like Los Angeles? It all depends on how you look. Previous surveys used fruit or other baits to catch fruit flies. The authors think that may be why these species were missed since both of these newly-noted flies breed on flowers, not fruit.
Instead, this study used a tent-like insect trap called a “Malaise trap,” thirty of which are housed in L.A. backyards, two gardens, and one school.
“The citizen scientists that host these traps share in the credit for this discovery, as do the museum and the Seaver Foundation, both of whom fund the BioSCAN project,” Brown said.
Will somebody, please submit pictures of these introduced species to Bugguide.net? I would appreciate it if somebody also let me know so I can include them in this list of Introduced arthropods. Notice that the list is incomplete.
Beatriz, contact Kelsey Bailey at the Natural History Museum of Los Angeles County for photos.