Tiny, iridescent Ormyrus labotus always looks suspicious to a parasitic wasp. It’s not the wasp’s striking beauty – wasps can be attractive in the usual way – but its survival strategy. Parasitic wasps lay their eggs on or inside other insects and arthropods, and the larvae feed on their exit as they hatch. Each species of parasitic wasp tends to prefer one or a few hosts. But Ormyrus labotus has been observed to lay eggs of more than 65 different species of insects – more than one or a few species.
Ormyrus labotus parasitizes wasps, which lay their eggs on plants and cause them to form protective, swollen structures called galls around the larvae (a parasite, within a parasite!). When galls from different species of wasps form, they come in a variety of sizes and shapes. Some are much tougher than others, some have unusual defensive strategies. There are gall bladders that are contained, which secrete nectar or filamentous hairs. Parasitoid wasps often have special adaptations that allow them to burrow into certain types of honey.
But Ormyrus labotus seems to have no problem penetrating a wide range of galls: round lemon-green and polka-dotted galls, spiky yellow galls on leaf blades, and stout galls on twigs. “It seems odd that one species can effectively attack all of them,” said Sofia Sheikh, a doctoral student at the University of Chicago who studied wasps while she was at the University of Iowa. different species of wasps.
It turns out that entomologists have good reason to be skeptical. After extracting DNA samples from parasitic wasps collected from oak trees around the country, Sheikh and colleagues at the University of Iowa revealed that Ormyrus labotus is actually a complex of at least 16 genetically distinct species that are essentially indistinguishable with the naked eye. . Their study was published Wednesday in the journal Insect systems and diversity.
This paper, the researchers note, is the latest in a series of studies showing that the supposedly generalized parasitic insects are complexes of many species. And scientists are more certain that this latent diversity lurks in insects that haven’t been studied for decades – there may even be more Ormyrus labotus species.
Josephine Rodriguez, an entomologist at the University of Virginia’s College at Wise who was not involved in the study, said the examples are teaching scientists to “be suspicious” of any known parasitic wasp species. supposed to be general.
Andrew Forbes, an evolutionary biologist at the University of Iowa, says the paper emerges from a larger project studying the co-evolution of North American wasps and their parasites. “No one has looked at these groups for 50 to 100 years,” said Miles Zhang, an entomologist at the USDA Systems Entomology Laboratory. founded by biologist Alfred Kinsey, who is better known. for the scale of human sexuality with the same name.
Sheikh and Anna Ward, an Iowa graduate student, spent several years stripping oak trees, which involved scouring iNaturalist, a social network of biologists and other scientists, and invite them into everyone’s backyard. They brought the honeys back to the lab, put them in separate cups in a refrigerator-sized incubator, and waited to see if the honey would spawn wasps, parasitic wasps, or all. two – two wasps with a stone. “It’s usually like 20 wasps with one stone,” explains Dr. Forbes. “Each wasp is attacked by 10 to 25 different species of parasites.”
As the wasps hatched and chewed through the holes that escaped their gall bladders, the researchers extracted DNA samples from the insects to test for genetic variation between them. They then compared the genetic results with ecological findings, meaning which species of wasp was found on which plant on which tree. They also study the anatomy of insects, which is less useful because wasps look so similar. This is how they discovered that wasps most likely represent at least 16 species. (There may be two more samples, but the researchers don’t have enough samples to be sure.)
While the researchers expected Ormyrus labotus to not be a single species, 16 to 18 distinct species came as a surprise. “These are all of these species in our small sampling,” said Sheikh. “It means there’s a lot more that we haven’t grasped yet.”
The paper does not formally describe or name any species in the complex, as such taxonomic work would require more evidence and microscopic measurements of the wasp body parts. . And DNA analysis only looks at a single bar-encoding mitochondrial gene. But Dr Forbes hopes someone will grasp the taxonomic shell and name each of the 16 to 18 long-ignored wasp species. “This study adds to the case where we need additional support to train and fund taxonomists,” said Dr.
Distinguishing dozens of species of wasps that look exactly alike from a single species of wasp is not just a classification exercise. The extreme specializations of Parasitoid wasps make them excellent pest managers; In Hawaii, the parasitic wasp species Eurytoma erythrinae has dramatically reduced populations of the wasp species that threaten native wiliwili.
In Dr Zhang’s opinion, entomologists often focus on bees and ants – the flashiest insects in the order Membrane – while ignoring the small wasps.
“They are undervalued because they are so small,” says Dr. Zhang. “But they are iridescent, with beautiful glowing eyes.”
Dr. Zhang, who works at the Smithsonian’s National Museum of Natural History, said the museum has at least 100 specimens labeled Ormyrus labotus. Small wasps are usually stored in drawers. But if exposed to light, their iridescent body will sparkle, looking different from every angle.
https://www.nytimes.com/2022/02/17/science/wasp-species-parasite.html A parasitic wasp revealed: One species is in fact 16 species