Cicada - an overview | ScienceDirect Topics (2024)

Structure and Function

Cicadas typically possess a broad head delimited by a pair of large compound eyes, a large pro- and mesothorax housing mostly wing and leg muscles, a small metathorax, an abdomen that in the male is highly modified to accommodate the organs of sound production and reception, and two pairs of membranous wings that are usually held tentlike over the body at rest.

The head is dominated by a large, noselike postclypeus that houses muscles for sucking sap through the rostrum; the three jewel-like ocelli detect the direction of light sources and, if asymmetrically covered, cause erratic flight.

The abdomen carries the organs of reproduction and of hearing and, in males, also sound production.

12.2.1.5 Hemiptera (cicadas, stink bugs, true bugs)

Cicadas are widely found in tropical forests primarily in tree trunks. The cicadas are commonly harvested using long grasses covered with the latex of Ficus natalensis trees. The latex is used to stick to the wings of cicadas and they will be removed before consumption (Huis et al., 2013). In southern and northern China, cicadas are consumed by frying and roasting (Feng et al., 2018). Stink bugs are mostly consumed in Africa and Zimbabwe and are widely found on tree trunks and branches. The stink bugs are harvested traditionally by climbing on the trees and shaking the branches intensively so that the bugs fall off the tree. Once harvested, the stink bugs will be immersed in hot water and proceed to cleaning and storing (Musundire, Osuga, Cheseto, Irungu, & Torto, 2016). According to the study conducted by Musundire et al. (2016), stink bugs are composed of high amounts of antioxidants and nutrients such as crude protein, fats, and phosphorus. True bugs are widely consumed in Africa, Mexico, and Sudan and these bugs can be consumed in various stages of their life cycle such as eggs, larvae, and adult stages. True bugs are usually consumed by frying and roasting. The eggs of true bugs are highly consumed by the Aztecs (Huis et al., 2013).

Description

3.31.4.2.1 Cicadas

In male cicadas the tympanal membranes of the ears and the sound producing tymbals are both backed by a large abdominal air chamber (Pringle, J. W. S., 1954; Hennig, R. M. et al., 1994). Since the animals generate high-intensity sound patterns in the vicinity of their hearing organs (Young, D., 1990) the auditory organ is prone to overloading by self-generated sound. During singing, however, the detensor tympani and ventral longitudinal muscles contract and act on the tympanal rim so that the tympana relax and fold (Pringle, J. W. S., 1954; Hennig, R. M. et al., 1994). Folding of the tympana reduces their tension and the sensitivity of the ears by 20dB; however, it does not completely disable sound perception.

3.02.2.2.3 Hemiptera (hom*optera + Heteroptera)

Cicadas (hom*optera, Cicadidae) are familiar to many of us because of the loud, high-pitched buzzing sounds they produce during hot weather. These sounds, usually produced by males calling to females, are generated by tymbal organs on the thorax, and often reach intensities close to 100dB at close range, equivalent to what one might experience standing near a smoke alarm. Cicada ears comprise a pair of large oval tympanal membranes located inside a protective cavity on the ventral side of the second abdominal segment. The tympanal organ is contained within a sclerotized capsule and attaches to the lateral border of the eardrum. Cicada ears are among the largest of insect tympanal ears with respect to tympanal area (reaching 4mm²) and the number of scolopidia (up to 2000 scolopidia per ear). The large number of cells is thought to enhance frequency discrimination, thereby allowing females to exploit additional components of the calling song (Fonseca, P. J. et al., 2000).

Many waterbugs (Heteroptera, subfamily Hydrocorisae) communicate acoustically (Aitken, R. B., 1985) but little is known about how they hear. Only one species, the water boatman, Corixa punctata, has been studied in detail. The round tympanal membrane occurs on the lateral mesothorax, between the forewing and the leg. A large club-shaped cuticular structure extends outward from the membrane, and the auditory organ, comprising only two scolopidia, attaches to the base of this club. Surprisingly, the acoustic cells in the left and right ears are asymmetrical in their tuning and thresholds, with the left ear being consistently more sensitive to higher frequencies than the right. These physiological differences have been attributed to differences in vibrational qualities of the tympanal membrane and the clubbed structure (Prager, J., 1976; Prager, J. and Larsen, O. N., 1981). The biological significance of this phenomenon is thought to be an accommodation for changes in the resonance properties of the tympanal membrane while the animal is diving (Prager, J. and Streng, R., 1982).

“hom*optera”

This group includes the cicadas, leafhoppers, aphids, scale insects, whiteflies, and their relatives. Nearly all feed on plants (a few on fungi), and are not predacious; and many are important pests of crops and ornamentals. Recent work on the origins and (especially) the evolutionary relationships of groups within “hom*optera” has led to the conclusion that the group did not have a unique ancestor common to all hom*opterans and to no other hemipterans. As a result, the higher classification of “hom*optera,” and the systematic status of the group itself, are deeply in question. That is why the author places the term “hom*optera” in quotation marks: The term is useful in grouping together a number of insects, but it is not useful in suggesting they compose a single evolutionary unit.

The Features of Substrate-Borne Signals

Above we referred to the sound of cicadas as agreeable from a distance, but up close they are ear-splittingly loud. High energy content is a major feature of animal airborne sounds. It is quite common for airborne acoustic signals to have sound pressure levels of 80–100 dB SPL (for reference, quiet conversation occurs at 70 dB SPL, and note that this is a logarithmic scale). This reflects selection on signals to reach a wide range of receivers, and presents the challenge to small animals (such as insects) of maximizing the energy they radiate onto a large volume of air (Bennet-Clark, 1998; Gerhardt and Huber, 2002). There are exceptions, with some airborne signals having remarkably low amplitudes, as the advertisem*nt signals of whispering moths (Nakano etal., 2009), or some forms of aggressive song in birds (Searcy etal., 2014). But airborne signals are largely selected to have high amplitude and radiate broadly.

By contrast, substrate-borne signals are often very low in energy, commonly involving minute movements of the surface of plant stems that propagate at low speeds (Cocroft and Rodríguez, 2005). This observation is often juxtaposed with another: the space occupied by potential receivers of substrate-borne signals is frequently small, restricted for example to the insects on a bush (Cocroft and Rodríguez, 2005). There are of course exceptions, as with the exceptional reach of potential vibrational signals in elephants (O’Connell-Rodwell etal., 2000, 2001), but such cases seem to be rare. A third common feature is that substrate-borne signals often exhibit remarkable complexity, as noted above (Fig.2). This is all the more striking when it involves small animals with small brains, as it often does.

Are these juxtapositions a coincidence? Or is there something about the relative lack of selection for large-volume radiation that frees animals to realize the behavioral complexity of which they are capable? Imagine that the repetitiveness of airborne insect signals, for instance, is designed to optimize transmission and detection in large noisy spaces (Guilford and Dawkins, 1991) rather than reflect constraints on cognitive abilities and behavioral complexity. This is not to ignore the high levels of noise in the substrate channel (see above). But perhaps there may be different dynamics, given common communication distances and noise patterns (Cocroft and Rodríguez, 2005), that explain the differences in energy levels and complexity.

3.1 Long range acoustic signalling and pair formation

Using tympanal ears, crickets, katydids, cicadas, grasshoppers and moths are capable of hearing sound in the far field (Gerhardt and Huber, 2002). In several species, the calling individual will move through a habitat while signalling, and the receiver may either remain stationary or move towards the signal upon hearing it. This strategy is advantageous if the signalling individual is a male and there is a low density of females in its vicinity as the movement will increase the likelihood of pair formation. The males of bladder grasshoppers are able to communicate over vast distances (~450m), but will often spend time calling from one location, before moving up to 500m to start calling again (Van Staaden et al., 2003). Utilising this strategy the male is increasing their chances of locating females that might otherwise be sparsely distributed or occurring at low densities (Römer et al., 2014). Additionally, calling this way may release the male from the attention of predators that may pick up on their acoustic signal and zero in on their location (Zuk and Kolluru, 1998).

Another strategy often used in insect pairing is duetting, where both males and females of the species produce sounds. It is almost always the male that produces the initial signal, to which the female replies. There are examples of duetting in katydids, grasshoppers and cicadas (Bailey, 2003; Marshall and Cooley, 2001). Insect movement during duetting is diverse, with the females in some systems not moving at all while there are examples where both partners will converge on one location through the perception of acoustic signals (Bailey, 2003).

The evolutionary origins of duetting in insects is not very well understood, yet some proposals for its emergence have been suggested. One theory stems from the idea that mate calling was ancestrally male driven, but pressures from eavesdropping predators and parasitoids drove the males to produce shorter, less frequent sounds. This would have the effect of making it harder for females to detect males, leading to a scenario whereby females started to produce calls of their own, allowing the males to locate the females (Bailey, 2003). Alternatively, the evolution may have been driven by costs associated with searching by the females, be that an energetic cost or the increased risk of predation (Raghuram et al., 2015). By duetting the risks are shared between the two sexes rather than just one, a scenario discovered in the tree cricket, Oecanthus henryi, where both sexes are equally at risk from one of its predators, the lynx spider (Torsekar et al., 2019).

Another energetic cost to factor in when considering the evolutionary origins of pair forming is the nutritional nuptial gift often provided to the female of the species by the male (McCartney et al., 2012). In many species of katydid the male will provide a nuptial gift of spermatophylax to the female (Gwynne, 2008). The size of this nuptial gift is predicted to affect the likelihood of the female of the species moving towards the male. Females of species in which the males invest more into the gift, which are then larger and more laden with weight, are predicted to be more likely to be the more mobile of the two in pair formation. There is some evidence to support this theory, with several species of the katydid genus Poecilimon providing evidence that correlates nuptial gift size with the movement ecology of the females (McCartney et al., 2012). There are even some cases where the gift has become so large, that the males undergo large time periods where they are unable to mate. In these scenarios, the females become the competitive sex, with males only calling for short durations, leaving the onus on the females to locate and find them (Mccartney et al., 2008).

Research into pair forming in the bush cricket, Ephippiger diurnus, found no evidence between male song calling traits, such as call rate, syllable number and peak frequency and the size of the nuptial gift (Jarrige et al., 2013). This indicates that females are unable to use calling song as a predictor of male nuptial gift quality prior to pair formation. Interestingly this same study did provide convincing evidence of male mate preference, with the size and quality of nuptial gifts offered by males varying with desirable female traits such as age and size. Why then, might females be listening for and choosing males based on their song? It may be that certain characteristics of song are heritable traits that would influence the attractiveness of male offspring. Another reason may be that a male's calling song does not necessarily advertise their true fitness. Signalling can be energetically costly (Prestwich, 1994; Reinhold et al., 1998), so much so that it is predicted to affect the quality of other sexually selected traits, such as nuptial gift size. One such study into E. diurnus found an inverse relationship between desirable call characteristics and immune response, suggesting that males exhibit different energy allocation strategies when it comes to reproduction (Barbosa et al., 2016). Some males may invest more heavily in immunity rather than reproduction, while others might invest more in song than in nuptial gifts. This may explain the discrepancy between male song traits and female preference. Female preference should exert directional selection on male call parameters, but it seems acoustic signals are being constrained by trade-offs with other traits in certain populations.

hom*optera (Cicadas and Others)

When there is an emergence of one of the species of periodical cicadas (family Cicadidae), many Americans, for whatever reasons, seem to regard them as legitimate fun food. During a recent (1990) emergence in Chicago and northern Illinois, for example, the Chicago Sun-Times carried several articles, the second of which began: “Millions of tasty, entrees-if-you-dare will be available for the gathering during the next month in northern Illinois, and some Chicagoans will want to know how cicada fanciers prepare them.” Several recipes were provided. Articles described cicada biology and how to prevent damage caused by egg laying on very young plants and urged Chicagoans to forego the use of insecticidal sprays. There were many radio reports, a cicada hotline, and even Time magazine published a recipe.

There are six species of periodical cicadas (Magicicada) in North America, three with a 13-year cycle and three with a 17-year cycle. The nymph remains in the soil, feeding on the roots of various plants until ready for the final molt. It then digs itself out of the ground, climbs the nearest tree or shrub, and attaches itself firmly. The adult lives for a month or longer. The so-called dog-day cicadas, such as those of the genus Tibicen, have shorter life cycles, but even they require at least 4 years. Cicadas are eaten in many countries, but probably most widely in the countries of southeastern Asia.