In a surprising and bizarre discovery, a team of biologists has identified a new species of wasp that resides within the adult fruit fly. This newly described species has been named Syntretus perlmani, and it exhibits a unique behavior of beginning its life cycle within the abdomen of adult Drosophila flies.
While parasitoid wasps commonly lay their eggs in various insects, approximately 200 species specifically target the larval form of Drosophila as their hosts. However, members of the Euphorinae subfamily, to which this new species belongs, have been observed attacking adult insects from different orders but have never been seen growing inside adult fruit flies.
The researchers first encountered this peculiar phenomenon while conducting a study in Mississippi in March 2023. During their investigation of nematode infections in flies, they stumbled upon a parasitoid wasp larva nestled within the abdomen of an adult male fruit fly. Subsequent mitochondrial DNA sequencing confirmed that it was a previously unidentified species of Syntretus.
Over the course of 11 months, the team meticulously examined over 6,000 male Drosophila affinis flies from various locations, including Mississippi, Alabama, and North Carolina, to identify instances of wasp larvae infestation. While the infection rate fluctuated between 0.5 to 3 percent throughout the year, less than 1 percent of the flies were found to be infected.
Further investigation revealed that the development of the wasp larvae within the host fly takes approximately 18 days from egg deposition. The larvae eventually chew their way out of the host’s abdomen, reminiscent of a chestburster, before pupating and emerging as adult wasps. Female wasps were observed ovipositing into flies within 24 hours of emerging from their cocoons, restarting the cycle.
The researchers also noted that the newly discovered wasp species exhibited a broad geographic distribution across the eastern United States and could be easily collected from backyard fly baits. This accessibility, coupled with its unique behavior, makes it an ideal study subject for biologists looking to explore various aspects of immunity, metabolism, ecology, evolution, and behavior.
Additionally, the researchers found that the wasp was capable of attacking other types of fruit flies, including the widely studied Drosophila melanogaster. This association with a laboratory model organism opens up new research opportunities in the field of life sciences.
The groundbreaking research detailing this fascinating discovery has been published in the prestigious journal Nature. This unique relationship between the wasp and the fruit fly offers valuable insights into the intricate interplay between different species in nature.
