Body Temperature and Responses of Periodical Cicadas (Homoptera: Cicadidae) to a Potential Predator

Abstract

Brood emergences of periodical cicadas are closely synchronized resulting in a mass emergence which represents an effective anti-predatory response (Lloyd and Dybas, 1966a, b). Not only does the mass emergence swamp the local populations of birds and mammals, but the long interval between emergences (13 or 17 yr) prevents a predator population from tracking these peaks in cicada populations. Furthermore, the chorusing of densely packed males produces a sound level that can deter birds from effective hunting (Simmons et al, 1971). Individual periodical cicadas are nonetheless vulnerable given the ease at which they can be approached (Beamer, 1931; Lloyd and Dybas, 1966b). Local avian predators take substantial numbers as evidenced by the increases in their populations in the year following a mass emergence (Koenig and Liebhold, 2005). Also, small mammals such as voles, mice and shrews show substantial increases of cicadas in their diet during a mass emergence (Hahus and Smith, 1990). Steward et al. (1988) reported that many individual cicadas of the 13-year species (Magicicada spp.) responded actively to an approaching predator by flying away, falling, or by squawking in males. The cicadas changed how they responded over the emergence period; fewer individuals remained stationary after the period of peak density compared with before, and more males squawked as a part of their response near the end than at the start of emergence. The present study was intended to determine how 17-year cicadas, Magicicada cassini Fisch (Homoptera: Cicadidae), would respond to a model avian predator and to compare their responses to that reported in the literature for 13-year cicadas. Even though a periodical cicada can fly when its body temperature is above 19 °C (Heath, 1967), its body temperature may affect its decision of when to escape by flying. Several species of lizards respond differently to an approaching predator at varying body temperatures (Huey, 1982; Cooper, 2000, 2006). Therefore, the body temperature of each cicada was recorded along with its response.