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Study Reveals How Little We Know About Wisconsin’s Insect Diversity

When you think of a Wisconsin animal, chances are you visualize a deer or a badger. But mammals, though highly visible, are just a small fraction of the state”s overall diversity of wildlife.

While there are a few dozen mammal species in Wisconsin, there are at least 18,000 insect species, according to a University of Wisconsin-Madison scientist. And, as illustrated by a recent survey of one group of beetles, this number is probably a very conservative estimate: no one knows how many there really are.

When it comes to biodiversity, nothing can beat insects – especially beetles, according to Dan Young, an entomologist with the College of Agricultural and Life Sciences. Between 70 and 80 percent of all animals are insects, and more than one out of every four animal species on earth is some type of beetle.

Young, director of the entomology department”s Insect Research Collection, currently leads a group of graduate students that aims to find out just how many beetle species live in Wisconsin. Members of the scarab beetle group of families – which includes “junebugs,” Japanese beetles, dung beetles and rose chafers – were the first to be counted in a recent survey.

And the number of scarab species they found may surprise you.

Until this survey, 120 species had been documented to live in the state. But Young”s graduate student, Nadine Kriska, turned up 177 species by searching scientific journals, examining museum and private collections, and combing through fields, meadows, and oak savannas.

However, Young says that it isn”t unusual to get up to a 90 percent increase in known species after a survey. “The average person assumes that we know a lot about the animals, plants and fungi in the state,” he says, “but this is not always the case. The state of Wisconsin has never had a history of conducting biological surveys, especially of insects.” In fact, the Insect Research Collection is the largest insect collection in the state, and it lacks information about many Wisconsin insect species.

That is a problem, Young says, because in order for organizations like The Nature Conservancy and the Department of Natural Resources to practice conservation biology, they need to know how to manage resources and habitats. This depends largely on what species are already there. And insects, which serve as predators, prey, pollinators and decomposers, drive the rest of the natural system. “You can”t be interested in biodiversity without knowing about insects,” he says.

In addition to an almost 50 percent increase in known species of scarab beetles, the survey shows how important certain habitats are in Wisconsin. It turns out that many species thrive in oak savannas, which rapidly disappeared from the southern third of the state as a result of development and expanded farmland. Given that a specific habitat holds many types of beetles, undoubtedly numerous other species live there as well, Young says. And, if the habitats disappear, beetles and many other creatures will suffer.

In addition to shedding light on biodiversity in Wisconsin and the importance of certain habitats, this type of study is also an excellent way to train future entomologists, says Young. “The student is exposed to a group, its anatomy, natural history, taxonomy and the research literature,” he explains.

Young is concerned by the lack of resources to survey insect diversity. “People want to know this information,” says Young, “but there is little research funding to do work like this. People believe this information is already there.” Unfortunately, he adds, there”s a lot yet to learn about Wisconsin”s insect species.