Biology majors Daniel Clement ’14 of Flint Hill, Va., and Anna Ledin ’16 of Lynchburg, Va., are working with Dr. John Styrsky in Panama this summer to solve some mysteries.
They are continuing the investigation of two sister species of orb-weaver spiders (Eustala oblonga and Eustala illicita) that inhabit ant-defended acacias (thorny bushes/trees).
“In the past I have shown that the spiders live among the deadly ants for their own protection — the ants dissuade any spider predators from attempting to eat the spiders,” Dr. Styrsky said in an email from Panama.
“Anna is working on an independent project to determine what the spiders catch in their webs. The spiders could be benefiting the ant-acacias in a sense in that they capture flying insect herbivores that might be flying to the plant. At the same time, however, the spiders could be capturing dispersing winged ant reproductives. So, basically Anna is trying to figure out what sort of effect the spiders might be having on the acacias and their ant bodyguards.
“Daniel is working on an independent project to determine how the spiders find the acacias in the rainforest. The acacias are quite sparse in the forest understory, so it is unclear how the spiders manage to find them. Daniel is testing the hypothesis that the spiders can detect airborne ‘volatiles’ that either the plants or ants (or both) produce and follow them to their source. He is collecting spiders and exposing them to air moving across ant-acacia plants and another understory plant in a device called a y-tube olfactometer to see if the spiders respond by moving towards the ant-acacias.
“Although the conditions are taxing in the rainforest (the forest understory is shaded, but very still with humidity in the mid- to upper-90 percent range; tangled masses of lianas and vines; mosquitoes, horseflies, and chiggers) we’ve seen lots of neat stuff including howler monkeys, Geoffrey’s tamarins (another monkey species), leafcutter ants, army ants, agoutis, coatis, sloths (at left), bullet ants, antbirds, toucans, and parrots. The students have also made an acquaintance with the local (huge) crocodile in the Chagres River near our apartments.
“We watched the World Cup at a nearby eco-resort along with several undergraduate and graduate students from around the world, all here doing research through the Smithsonian Tropical Research Institute.”