Meeting Abstract

P2.88  Sunday, Jan. 5 15:30  Mechanical properties of the cuticles of three cockroach species in relation to wind-evoked escape behavior CLARK, AJ*; TRIBLEHORN, JD; College of Charleston; College of Charleston clarkaj@cofc.edu

Many insects employ rapid movements or body armor to protect against predatory attack. There are often tradeoffs between these behavioral and morphological forms of active defense. For example, in a heavily armored insect, the increased body weight reduces its ability to perform rapid escape responses. This tradeoff can be found in cockroaches (Blattaria). Periplaneta americana exhibits strong wind-evoked escape responses involving rapid turning and running. This response is weaker in Blaberus craniifer and absent in Gromphodorhina portentosa, putting these species at greater risk of being struck by a predator. These two larger species possess more robust exoskeletons that could provide more protection from predatory strikes compared to the lighter exoskeleton of P. americana, but the protective biomechanical properties of cuticle in these three species have not been quantified. Here, we measured these properties by testing the tensile strength and puncture resistance of the thoracic and abdominal cuticles in these three species. As predicted, the cuticles of both B. craniifer and G. portentosa were significantly stronger and more resistant to puncture forces than the cuticles of P. americana. Relative to P. americana, tensile strength of the thoracic and abdominal cuticles was three times greater in B. craniifer, and six times greater in G. portentosa. Peak puncture forces were five times greater in B. craniifer, and twenty times greater in G. portentosa. Our results, coupled with results from previous studies on wind-evoked predator avoidance behaviors in these cockroach species, support the hypothesis of an important tradeoff between rapid body movements and robust cuticles.