Periodical cicadas use light for oviposition site selection

Organisms use incomplete information from local experience to assess the suitability of potential habitat sites over a wide range of spatial and temporal scales. Although ecologists have long recognized the importance of spatial scales in habitat selection, few studies have investigated the temporal scales of habitat selection. In particular, cues in the immediate environment may commonly provide indirect information about future habitat quality. In periodical cicadas (Magicicada spp.), oviposition site selection represents a very long-term habitat choice. Adult female cicadas insert eggs into tree branches during a few weeks in the summer of emergence, but their oviposition choices determine the underground habitats of root-feeding nymphs over the following 13 or 17 years. Here, field experiments are used to show that female cicadas use the local light environment of host trees during the summer of emergence to select long-term host trees. Light environments may also influence oviposition microsite selection within hosts, suggesting a potential behavioural mechanism for associating solar cues with host trees. In contrast, experimental nutrient enrichment of host trees did not influence cicada oviposition densities. These findings suggest that the light environments around host trees may provide a robust predictor of host tree quality in the near future. This habitat selection may influence the spatial distribution of several cicada-mediated ecological processes in eastern North American forests.     

Chronic speciation in periodical cicadas

Allochronic speciation and reproductive character displacement are two intuitively attractive models of speciation. The first proposes that changes in the timing of life cycles produce new species, whereas the second suggests that speciation is due to the exaggeration of sexual isolation in sympatric populations. Clear examples of either process in nature remain elusive, despite some extensive searches. Two recent studies of mtDNA markers and behaviour of periodical cicadas in North America have identified a new species of cicada that seems to provide good evidence for the involvement of both processes in its origin.     

Isolation of two AKH-related peptides from cicadas

Two peptides related to locust adipokinetic hormone and crustacean red pigment concentrating hormone were isolated by high performance liquid chromatography from the cicadas Cacama valavata and Diceroprocta semicincta. Both species have the same peptides. The structure of one of the peptides is pGlu-Val-Asn-Phe-Ser-Pro-Ser-Trp-Gly-Asn-amide. The mass spectrum, amino acid composition, and amino acid sequence of the other peptide suggest that it is almost identical to the first peptide. However, the exact nature of the difference between the two peptides could not be determined. © 1995 Wiley-Liss, Inc.     

Complex co-evolutionary relationships between cicadas and their symbionts

Previous evidence suggests that cicadas lacking Hodgkinia may harbour the yeast-like fungal symbionts (YLS). Here, we reinforce an earlier conclusion that the pathogenic ancestor of YLS independently infected different cicada lineages instead of the common ancestor of Cicadidae. Five independent replacement events in the loss of Hodgkinia/acquisition of YLS and seven other replacement events of YLS (from an Ophiocordyceps fungus to another Ophiocordyceps fungus) are hypothesised to have occurred within the sampled cicada taxa. The divergence time of YLS lineages was later than that of corresponding cicada lineages. The rapid shift of diversification rates of YLS and related cicada-parasitizing Ophiocordyceps began at approximately 32.94 Ma, and the diversification rate reached the highest value at approximately 24.82 Ma, which corresponds to the cooling climate changes at the Eocene–Oligocene boundary and the Oligocene–Miocene transition respectively. Combined with related acquisition/replacement events of YLS occurred during the cooling-climate periods, we hypothesise that the cooling-climate changes impacted the interactions between cicadas and related Ophiocordyceps, which coupled with the unusual life cycle and the differentiation of cicadas may finally led to the diversification of YLS in Cicadidae. Our results contribute to a better understanding of the evolutionary transition of YLS from entomopathogenic fungi in insects.     

Flight and dispersal of periodical cicadas

Summary Periodical cicadas (Magicicada spp.) rarely flew distances greater than 50 m across an open field or along a forest edge. Most cicadas caught after flying 50 m or more were females and all of these females had mated. Flights were most common when adults were 2 to 3 weeks old. Among insects in general, most dispersing individuals are barely post-teneral or extremely young. Cicadas are discussed as an exception to this generality. Both sexes of cicadas are attracted by the male song to chorusing centers for mating (Alexander and Moore 1958). Trees which were chorusing centers had more eggnests than those which were not, suggesting a lack of postmating dispersal from the chorusing trees.     

How 17-year cicadas keep track of time

Seventeen-year periodical cicadas ( Magicicada spp.) require 17 years to develop underground and all individuals at any location emerge synchronously within several days. The mechanisms that animals use to keep track of time are poorly understood and nothing is known about how cicada nymphs emerge after precisely 17 years. We altered the seasonal cycles of trees supporting cicada nymphs and thereby induced premature metamorphosis of the associated cicadas. This indicates that cicadas accomplish a consistently accurate 17-year preadult development time by counting host seasonal cycles and not either by the passage of real time or by the accumulation of degree days.     

The songs and calling sites of two European cicadas

Abstract. 1. The male songs of two of the commonest cicadas in southern France are described with oscillograms.
2. Males of Cicada orni L. aggregate during calling whilst those of Lyristes plebeius (Scop.) space themselves out.
3. Both species are widely polyphagous on trees and shrubs, but L. plebeius sings from thinner stems than does C. orni
4. Such behaviour may result in the spatial separation of different species in the same habitat.     

Ecophysiological responses to climate change in cicadas

Cicadas are large hemipteran insects characterized by unique life‐history traits, such as extraordinarily long life cycles, a subterranean/terrestrial habitat transition, xylem sap‐feeding and melodious sound production. These fascinating features of cicadas have attracted much attention in the research fields of physiology and ecology, resulting in an accumulation of knowledge about the underlying mechanisms and their adaptive significance. Although community‐level responses to recent climate change have already been documented for cicada fauna, an understanding of their causal relationships is still at the initial stages. In this review, we summarize current knowledge about environmental adaptations of cicadas to facilitate a deeper understanding of the ecophysiological consequences of climate change. We first outline the diverse responses of cicadas to environmental factors, mainly temperature, and their strategies to cope with naturally fluctuating environments. Then, we discuss the consequence of upcoming climate change by consolidating the current findings. This review highlights the fact that fitness‐relevant activities are fine‐tuned to a species‐specific temperature optimum to achieve habitat segregation among coexisting species, implying that cicada diversity is highly susceptible to climate warming. As a result of their conspicuous large bodies and species‐specific calling songs, cicadas are promising candidates for use as bioindicator species to monitor ecological impacts of climate change. We encourage future works that continuously quantify population‐ and community‐level responses to upcoming climate change, as well as unveil mechanistic links between physiological traits and ecological consequences.     

Asymmetric song responses in coexisting Japanese cicadas

Diel partitioning of singing, which has been observed from the tropics to the temperate regions, is among the various mechanisms of sound partitioning found in multispecies cicada assemblages and is regarded as an important mechanism of coexistence. Using playback experiments, we studied interspecific interference between two Japanese cicadas, Cryptotympana facialis and Graptopsaltria nigrofuscata, which exhibit similar peak frequencies in their calling songs and different diel patterns of song activity. We found that the males of the two species had different song response patterns: C. facialis responded significantly more to conspecific calling songs than G. nigrofuscata. These results suggest that male C. facialis have evolved more intense conspecific song recognition than G. nigrofuscata. This may cause male G. nigrofuscata to avoid destructive acoustic interference during their active singing time.     

Differential susceptibility of tree species to oviposition by periodical cicadas

Abstract 1. Periodical cicadas occur widely in deciduous forests of eastern North America and represent the largest insect emergences in the world. Their effects on forest community dynamics, via oviposition damage and root feeding, are potentially great but not well understood. If tree species vary in their susceptibility to cicada oviposition and root colonization, then periodical cicadas may affect ecological interactions among tree species and forest composition. 2. We measured oviposition damage on 63 tree species at 52 sites in southern Indiana, U.S.A. for two broods of periodical cicadas. We compared oviposition damage among different sites, habitats, and tree species. We also measured cicada emergence rates in mature and successional forest habitats and from beneath different tree species. 3. Certain tree species received significantly more oviposition damage than others, and the most and least damaged species were consistent between the two broods. For some species, oviposition damage varied between mature and successional sites. Despite the differences in oviposition rates among species, there was no difference in emergence rates from beneath different tree species, suggesting that initial differences in cicada density among tree species are not maintained through the nymphal life cycle. 4. Cicadas oviposited more at successional sites, but emerged more in mature forest stands, suggesting that successive generations of cicadas represent a shifting mosaic between forests of different ages. As tree species consistently vary in their susceptibility to oviposition damage, periodical cicadas could alter local competitive interactions and therefore affect forest dynamics.     

Periodical abstracts

Abstract

In a sample of 51 like‐sex DZ twin pairs (22 male, 29 female) 49 quantitative traits were analyzed for association with, and linkage to, each of 7 informative blood systems. Nine associations were found to be significant at the 0.01 level, and a further 27 significant at the 0.05 level, whereas the numbers expected to be significant by chance alone are about 3 and 17 respectively. The most consistent associations are those of Rh with the scores obtained with Paul Griéger's characterological test. The associations may be due to a factor present in the physical or social environment that influences both characteristics simultaneously; alternative explanations are pleiotropy, epistasis, or heterogeneity of the populations. Only 12 of the tests for linkage were significant at the 0.05 level, less than would be expected by chance alone; these results are therefore inconclusive. The most significant linkage is that between Hp and activity, one of the 3 scores in Griéger's characterological test. In vew of independent data suggesting evidence of linkage between Hp and depression spectrum disease, further study of this possible linkage in larger families would be warranted.