PARASITES INVENTORIED WORMING THEIR WAY INTO TEXAS WILDLIFE

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COLLEGE STATION — Everyone has a relative like this. You know, the one who overstays a visit, eating you out of house and home; the one who always borrows money from you, since you’re the one with a job. Parasite, you might say.

That fairly describes the way it is in the lesser animal kingdom, as well, a Texas Agricultural Experiment Station parasitologist says.

“A parasite is a part of the ecosystem that just happens to have a peculiar way of making a living,” Dronen said. “About 50 percent of the animals in today’s ecosystem are parasitic at some point in their lifetime.”

Dronen should know. He’s been tracking metazoan helminths – that’s worms, to you – for decades. Dronen manages the state’s ever-increasing wildlife parasite inventory, which he hopes to have available on the Web within a year.

In about three decades, Dronen has described 50 new parasitic worms — many of them only visible under a microscope — and collected hundreds more from colleagues, the Veterinary Medical Diagnostic Lab at Texas A&M, and other state and federal agencies.

“I have a lot of sources that help me find parasites,” he said. “And I go and collect for myself, mostly from salvaged specimens (such as road kill or illegally-hunted animals that are seized).”

But Dronen said the inventory of wildlife parasites is more than an museum collection — it’s useful as an indicator of the health of an ecosystem.

“If an area doesn’t have a diversity of parasites, there’s something wrong,” Dronen said.

Yet, parasites can have either a huge impact on a host — like the relative who stays long enough to clean out the cabinets — or can have a minimal impact, say a friend who overstays but at least keeps your house clean.

Regardless, “parasitic energy comes from the host, and what it takes can’t be used by the host,” Dronen said. “So is there a goodness to parasitism? I don’t think so.”

Dronen’s research with the collection, therefore, explores the full implication of what it means for animals, or groups of animals, to have parasite infestations. He looks as the type of geography where the parasites occur, what might have brought them in and other components, such as population crowding, and land fencing and fragmentation.

He sited research on the great blue herons of the Texas Gulf Coast.

“Where the Matagorda Bay is highly polluted, great blue heron have few species of parasites, but are full of them,” he noted. “Yet, up at Galveston, the same bird has lots of parasite species but not a lot of them.

“That might mean that a limited food source (in the polluted area) makes a difference, but we are not sure yet,” he added. “So we are studying whether we can use parasites as an indicator of pollution.”

Dronen said he would be able to publish information on what he has already found for the rest of his career, even if he did not collect another specimen or any data. But that’s not likely to happen. Parasite collecting and identification has grown on him.

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