University of Rhode Island Kingston, Rhode Island, United States
Predation pressure is a major selective force upon prey species, forcing organisms to invest energy into defenses and anti-predator behaviors. Domestication can remove the threat of predation, selecting for individuals that put less energy into defense and more into growth and reproduction. Populations reared for laboratory research (such as lab rats) are often docile compared to their wild counterparts, lacking strong anti-predator behaviors. We observed that lab-reared larvae of the gypsy moth, Lymantria dispar, are more sedentary and docile than wild L. dispar larvae. The lab-reared larvae develop and pupate faster than the wild larvae; we hypothesize that these higher growth rates may be correlated with reduced energetic investment in defensive behavior. We exposed both lab-reared and wild larvae to auditory predation risk (wasp buzzing) and found that predation threat significantly increased mortality in the wild larvae over the no-sound control treatment. The lab-reared larvae did not display any significant difference in mortality between the predation threat and control treatments, suggesting that they have reduced responses to predation threat. While lab-reared insects are commonly used in experiments for convenience, our results show that their behavior may not always be a perfect analogue to their wild counterparts.
