GATLINBURG, Tenn. -- In eastern Tennessee’s Smoky Mountains National Park, the only place you can now see a rusty patched bumblebee is inside of a drawer, part of the park’s nature collection.

Entomologist Becky Nichols leads the study of insects at the park.

“We haven’t seen them in the park since 2001,” she said.

The only remaining rusty patched bumblebees at Great Smoky Mountains National Park CBS News

Rusty patched bumblebees, important pollinators for tomatoes, nest underground.

Becky Nichols CBS News

Over the last 20 years, the species has suffered a 90 percent decline in population and habitat, a range that that once included 28 states and stretched into the upper Midwest and Northeast.

“Loss of habitat protectors, pesticides, diseases, all of these things can contribute to the overall decline of pollinators,” Nichols said.

Bumblebees, honey bees, butterflies; In all, about 40 percent of so-called invertebrate pollinator species now face extinction. About 75 percent of the world’s food supply depends at least partly on what they do.

“Every one-in-third bite of food is pollinated by bees. A huge factor is the bumble bee itself,” said Prof. Sydney Cameron, who teaches etymology at the University of Illinois.

Prof. Sydney Cameron CBS News

“A lot of our food is dependent upon these bees. If that’s not important, I don’t know what is,” she said.

But Nichols sees new hope.

“The first bumblebee to be placed on the endangered species list hopefully will be a little more than a wakeup call to what we are doing to the pollinators and they are doing for us,” she said.

Some groups may oppose the enhanced protection and regulation for this bumblebee, including pesticide companies, big agricultural interests and developers. But experts hope that one day these bees can reappear in areas where they once were so abundant.