Aaron Ellison, Fisher Associate
Professor of Biological Sciences, takes a look at some ants he has
just collected in a bog in Belchertown, as fellow researcher Rebecca
Emerson '01 looks on.
Ants are the most common prey of the
pitcher plant, which is composed of hollow stalks filled with rain
water. When insects, such as these ants, are unlucky enough to fall
inside, a hair-like apparatus lining the stalk's interior keeps the
plant's dinner from escaping.
Aaron Ellison, Fisher Associate Professor of Biological Sciences, views science as an open-ended set of questions. "One question inevitably spawns another, leading to new areas of inquiry," he says. Ellison should know. An expert on carnivorous plants, his research on the nutritional processes of the pitcher plant has led to a discovery outside his area of expertise. Ellison, along with MHC students Rebecca Emerson '01, Kirsten McKnight '03, and Samantha Williams '01, is becoming an authority on ants.
During the summer of 1998, while studying interactions between carnivorous plants and insects in Massachusetts and Vermont bogs, Ellison and Tuyeni Mwampamba '00 completed an intensive sampling of insects at Hawley Bog in northwestern Massachusetts. The bog, which is owned by Five Colleges Inc. and managed by the Massachusetts chapter of the Nature Conservancy, is used by students and faculty as an outdoor classroom. By setting traps (beer cups filled with water, as well as tuna packed in canola oil and placed on index cards), Ellison and Mwampamba collected about eighty ants in the Hawley bog and sent them for identification to Harvard ant scholar Stefan Cover and University of Vermont Associate Professor Nicholas Gotelli.
Ants are the most common prey of the pitcher plant, which is composed of hollow stalks filled with rain water. When insects are unlucky enough to fall inside, a hair-like apparatus lining the stalk's interior keeps the bugs from escaping. Organisms inside the plant help it digest its meal. Some of the collected ants turned out to be a new record for the Commonwealth of Massachusetts (scientific terminology for the first known occurrence). The final identification of the ants is not expected until sometime this fall, but Cover believes that the ants are a new record either in the area east of the Rocky Mountains or in the continental United States. The tip off was the unusual shape of the ants' antennae and microscopic anatomical characteristics.
Ellison
contacted the Massachusetts Heritage and Endangered Species Program
(MHESP), part of National Fish and Wildlife Service, and discussed
the finding with scientists there. They were interested, having just
completed a survey of the vegetation of Massachusetts bogs. The MHESP
awarded Ellison a grant to survey ant species diversity this summer
in a subset of Massachusetts bogs (those with pitcher plants and
those in excellent condition) in areas ranging from Provincetown to
the Berkshires. The MHESP grant funded Emerson, while the National
Science Foundation funded Williams and McKnight.
The stage was set for a summer of intensive ant collecting, a project that was no picnic. In order to access the bogs, the researchers hiked through dense vegetation, most often without the benefit of trails. One false move could leave them waist-deep in muck. Undaunted, Emerson says it was "exciting to see so many different habitats." The group visited fourteen bogs over the course of the summer. At each site, they left traps at twenty-five locations, returning two days later to collect specimens. In addition, they conducted vegetatian analyses and collected ants in nearby forests. After Ellison taught them how to collect the ants (using a device that draws the ants into a tube filled with alcohol), the students were responsible for gathering more than 4,000 of the insects.
Back at the lab, Ellison and the students learned to identify ants. Using diagrams of ant anatomy and reference specimens to recognize the hallmarks of individual species, they identified twenty-four different types of ants. "I can even identify ants by the shape they make after being submerged in alcohol," Emerson notes. Ellison will spend this year analyzing data collected over the summer, focusing on whether there are distinct ant groups in forests vs. bogs; the relationship between vegetation and ant species diversity; patterns of coexistence among ants; the range of particular ant species; whether different ants have different nutritional value for the plant; and how the health of the plant is affected by the type of ants it consumes. In addition, he will prepare an inventory of ant species in Massachusetts bogs for a report due to the MHESP by May 2000.
Arachnophobics beware! There may soon be hundreds of spiders on campus. While collecting ants, Ellison and his students came across many different spiders, giving birth to yet another line of scientific inquiry--the role of spiders in controlling ant species diversity. Emerson, who is taking a year off from her studies, will continue to work with Ellison, spending twenty hours a week largely on spider identification.
![[Index]](../index3.gif){kind=small}