Studies on insect defenses have investigated the benefits of noxious chemicals, aposematic coloration, and even gregariousness, but little information exists on the role of slow movement (as opposed to rapid escape movement and the absence of movement). Using the chemically defended, slow-moving lubber grasshopper (Romalea guttata) and the northern leopard frog (Rana pipiens), we investigated the role of slow movement in insect defense. In a five-day experiment, frogs did not learn an aversion to lettuce-fed lubbers; we infer that endogenous deterrent chemicals are not important in lubber defense from frogs. In experiment 2, lubbers moved significantly more slowly than crickets in the presence of frogs held under beakers. In experiment 3, control (i.e., slow-moving) lubbers suffered significantly less predation than motion-induced lubbers, and frogs attacked control lubbers significantly later than they attacked motion-induced lubbers. Hence, slow movement appears to be an important component in enhancing lubber survivorship in frog encounters. This is the first demonstration that the slow movement of an␣aposematic insect increases its survival by failing to release the attack response of certain motion-oriented predators.
We examined interference competition during interspecific interactions of larval anurans to determine its importance. We conducted laboratory experiments to examine behavioral and chemical interference competition between tadpoles of the southern leopard frog (Rana utricularia) and those of the green treefrog (Hyla cinerea). Water preconditioned byR. utricularia tadpoles significantly decreased the growth and increased the mortality of H. cinerea tadpoles compared with control treatments. In addition, R. utricularia tadpoles inhibited the feeding rate ofH. cinerea tadpolesby harassing them, and these interactions significantly decreased the growth and increased the mortality of theH. cinerea tadpoles. Rana utricularia tadpoles apparently use both chemical interference and aggressive behavior in securing a competitive advantage over H. cinerea tadpoles, and the H. cinerea tadpoles suffer from these interactions. Intraspecific chemical and behavioral interference competition also significantly decreased the growth of larval H. cinerea. In natural ponds, R. utricularia tadpoles that inhibit the growth and increase the mortality of H. cinerea tadpoles may increase their own chances of survival and metamorphosis, while H. cinerea tadpoles that avoid interactions with conspecifics and with R. utricularia tadpoles may increase their own chances of survival and metamorphosis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.