WPI Research is the research magazine of Worcester Polytechnic Institute. It contains news and features about graduate research in the arts and sciences, business, and engineering, along with notes about new grants, books, and faculty achievements.
Issue link: http://wpiresearch.epubxp.com/i/229254
Gegear and PhD candidate Melissa Mobley are studying the effects of commonly used pesticides on bees' mental agility; the chemicals appear to compromise the insects' ability to forage and pollinate plants, a serious concern since those plants provide one-third of the world's food supply. Gegear proposes that plants, through the evolution of diverse traits, are actually manipulating the bees and other pollinators toward specialization — shaping their brains and behavior in ways that benefts the plant. "Bumblebees are, by nature, generalists; they'll visit any fower as long as it has nectar or pollen. All they care about is getting as much as they can per unit of time." But less switching between species is better for the plants, because mixing pollen interferes with fertilization. "So there is co-evolution — but there is also confict." His research shows that increased foral complexity substantially increases the cost of switching among different fowers. This makes adopting a more specialized foraging strategy a better economic option for the bee. "In this way, foral specialization makes perfect adaptive sense from the bee's perspective," Gegear says. "This work on mental fexibility in bees has also provided valuable insight into the adaptive function of foral complexity in plants." Gegear is currently working with Elizabeth Ryder, associate professor of biology and biotechnology, on computer models they hope will help identify key factors that drive the emergence and persistence of sophisticated cognitive abilities in the bee brain and elsewhere in the natural world. POLLINATORS IN PERIL While natural selection has shaped the cognitive skills that have helped bumblebees survive, unnatural factors, including man-made chemicals, may be compromising those abilities and threatening the insects' long-term prospects. To help understand the possible connection between environmental stressors and recent declines in bee populations, Gegear is studying the effects of commonly used systemic neonicotinoid pesticides on bees. He is also exploring the impact that pathogens in the bees' environment may have on them by stressing the bees' immune systems in a way that mimics infection. He has demonstrated that "compromised" bees don't forage as effectively as control bees that haven't been exposed to pesticides or pathogens. The results indicate that exposure impairs mental fexibility, reducing the bees' ability to collect pollen and nectar, as well as other survival skills. "They basically become stupid," Gegear says, "and that makes them ineffcient foragers and more susceptible to predators. If the foragers can't bring back adequate amounts of nectar to sustain their colony and establish new ones, over time this will lead to population decline." The next step is to extend this work into the feld and look at long-term effects of chronic exposure on wild bumblebee populations. "It's not enough just to set an acute lethal limit for these pesticides," says Gegear. "In the wild, bees are visiting thousands and thousands of fowers in a day, each bearing a tiny bit of pesticide." Over time, constant exposure to these neurotoxins could cause increased mortality in workers and reproductives (queens and males) or have indirect effects on colony survival through impaired cognitive function of foragers. "Human-induced environmental change poses a serious threat to bumblebees and other pollinators worldwide," Gegear says. "Many species are in decline and some are on the verge of extinction. If we don't fgure out the cause of these declines soon, we will continue to lose pollinators. And if we lose all of our pollinators, we're in deep trouble." Re Worcester Polytechnic Institute > 15