Based on a joint study between Dr. Spencer Behmer, a Texas A&M University assistant professor of entomology, and researchers at the University of Oxford, the United Kingdom, the grasshopper would likely have developed this preference based on its physical state at the time its reserves were low, and it was hungry.
"When you're deprived, things taste better, and their perceived value may be exaggerated," said Behmer, who has a joint appointment with the Texas Agricultural Experiment Station.
Behmer studied the phenomena of 'state-dependent learned valuation' in a grasshopper, the African desert locust, Schistocerca gregaria, at the University of Oxford before moving to Texas A&M in August. He collaborated with Dr. Lorena Pompilio, who was then a graduate student, and Dr. Alex Kacelnik, her major adviser. Their study was published in Science on March 17.
"This work suggests that researchers may need to pay more attention to the state of the subject whether vertebrate or invertebrate at the time of learning," Behmer said.
"African desert locusts were used because they are known to be good learners, which may be important as they are extreme generalists when it comes to their diet they eat just about any kind of plant," Behmer said. "Learning allows them to make quick decisions about whether they should eat a particular plant."
During the study, locusts were trained under one of two conditions hungry or well-fed for separate parts of the day (morning or afternoon). In each state, they were repeatedly given a small piece of wheat, and at the same time, exposed to an odor, either peppermint or lemon grass.
Training lasted for three day
Contact: Dr. Spencer Behmer
Texas A&M University - Agricultural Communications