Emergence of 13‐Yr Periodical Cicadas (Cicadidae: Magicicada): Phenology, Mortality, and Predators Satiation

Abstract

We examined emergence of male and female 13-yr periodical cicadas (Brood XIX) and mortality, due to avian predation, fungal infection (Massospora cicadina), environmental factors, and senescence. We compared relative contributions of the sources of mortality, and determined the temporal pattern of avian predation associated with predator satiation and mortality. Based on a mean density of 6.65 emergence holes/m 2 , we estimated that 1 063 300 cicadas emerged on our 16-ha study area in northwestern Arkansas during May 1985. Males appeared first in emergence traps in early May and emerged more synchronously than did females. About 50% of the population emerged during four consecutive nights, and peak abundance of adult cicadas occurred in late May. Based on samples from mortality traps, at least 40% of the population died in severe thunderstorms during the first week of June, demonstrating that stochastic factors can be major influences on periodical cicada populations. Fungal infection was not a major source of mortality.The first cicadas that emerged in early May were eaten by birds, but avian predators became satiated. Birds consumed 15-40% of the standing crop at low cicada densities, but very little of the standing crop was consumed when cicada densities were > 24 000 individuals/ha on the study site. Avian predators appeared to be satiated for several weeks, and by the time their foraging activities increased due to demands imposed by feeding young, density of adult cicadas was relatively low. Mortality due to predation gradually increased to near 100% as the density of adult cicadas declined in June. Based on estimates of cicada emergence and deaths due to avian predation where adult cicada activity was greatest, birds consumed only ~ 15% of the adult cicada population. Therefore, only a small proportion of the adult cicada population was actually consumed by avian predators. These results demonstrate that, indeed, the synchronized, explosive emergences of periodical cicadas may be classical examples of predator satiation.

Allee effects, extinctions, and chaotic transients in simple population models

“…For example, in field studies Crawley and Long (1995) found that per-capita rates of acorn loss of Quercus robur L. to invertebrate seed predators were greatest (as high as 90%) amongst low acorn crops and lower (as low as 30%) on large acorn crops. In field studies, Williams et al (1993) found that birds generally consumed nearly 100% of the population as the density of adult cicadas declined in June, but they consumed proportionately very little of the standing crop when cicada densities were greater than 24,000 individuals/ha. Furthermore, predation on bird eggs and nestlings often decreases with increasing colony size (Wiklund and Andersson, 1994) and some fish species form large schools to minimize vulnerability to predators (Ehrlich, 1975).…”

The Ecology, Behavior, and Evolution of Periodical Cicadas

“…Densities of emerging cicadas (14,19,21,28,58,61,64,74,75,76,116,127,129,130,136) range from less than 30,000 ha-1 (76) to over 3.5 million ha-1 (19,61). That translates into a biomass of over 0.5 metric tons ha-1 and represents tremendous productivity (19,61).…”

“…That translates into a biomass of over 0.5 metric tons ha-1 and represents tremendous productivity (19,61). Most members of a population emerge within 7-10 days of each other (14,20,31,60,76,90,136), but emergence can be protracted by rainy or cool weather (7). In the weeks prior to nymphal emergences, periodical cicadas extend their tunnels to the soil surface, and some build mud turrets around emergence holes (5,14,19,80).…”

Seasonal persistence of marine‐derived nutrients in south‐central Alaskan salmon streams

“…These pulsed subsidies-exemplified by events such as insect mass emergence (Williams et al 1993) and mast fruiting in plants (Ostfeld et al 1996)-are readily exploited by generalist consumers due to their ability to switch prey Keesing 2000, Sears et al 2004) and can generate bottomup perturbations that influence population dynamics and community structure across multiple trophic levels (Yang et al 2008). When recipient food webs have effective storage mechanisms, the influence of pulsed resources may last far longer than the availability of the resource (Yang et al 2008).…”