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Ormyrus labotus

A parasitoid wasp revealed: 1 wasp is actually (at least) 16 species

Sofia Sheikh, E&E PhD student & lead author

Ormyrus labotus, a tiny iridescent parasitoid wasp, seemed to have an unusually expansive life strategy. Typically, parasitoid wasps lay their eggs on or inside other insects and arthropods, and larvae eat their way out when they hatch. While these wasp species tend to prefer just one or a few hosts, Ormyrus labotus had been observed laying eggs in more than 65 different species of insects, including an assortment of galls.

“It seemed weird that one species could be sort of effectively attacking all of these different galls,” said Sofia Sheikh, an E&E doctoral student who did research on these wasps while at the University of Iowa (UIowa). Sofia and her UIowa colleagues extracted DNA samples from parasitoid wasps collected from oak trees around the country, and discovered that Ormyrus labotus is a complex of at least 16 genetically distinct species that are indistinguishable to the eye.

Their research was published this February in Insect Systematics and Diversity. This paper is the most recent in a string of studies unmasking supposedly generalist parasitic insect species as complexes of many species.

                

Sofia and Anna Ward, another UIowa graduate student, spent several years pulling galls from oak trees. Often, this entailed searching iNaturalist, an online network of biologists and other scientists, and then inviting themselves into people’s backyards to collect the galls. They brought them back to the lab, placed them in separate cups in a refrigerator-size incubator, and waited to see if each gall would hatch gall wasps, parasitoid wasps, or both. As the wasps hatched and chewed their way out, Sofia and her team extracted samples of the insects’ DNA to examine the genetic variation among them.

While they expected Ormyrus labotus was not a single species, finding 16 to 18 distinct species came as a surprise. “Here are all these species in our small sampling,” Sofia noted. “It means there’s a lot more that we just haven’t captured yet.”

Researchers are increasingly certain that even greater hidden diversity lurks in insects that have not been studied for decades. And these examples continue to teach scientists to be suspicious of any parasitic wasp species currently believed to be generalists.