Mating System

The long-range female-attracting songs and long tactual cerci of crickets are components of a unique mating system, some aspects of which evidently trace to the earliest instances of copulation in the insect line and help explain changes leading to the current major groups of insects. Thus, none of the primitively wingless modern insects copulate, while all winged and secondarily wingless insects do, the majority with the male mounting the female and in some way holding or forcing her. In primitively wingless insects, however, a sac or bulb containing the sperm (a spermatophore) is transferred indirectly to the female without direct copulation. Like crickets, some of these particular primitively wingless insects possess prominent tactual cerci (e.g., Thysanura), used to guide the female during spermatophore transfer, as also in cockroaches and mayflies. In all insect groups of ancient origin that have prominent tactual cerci, transfer of the spermatophore is a luring act in which the female either mounts (winged and secondarily wingless forms) or stands beside the male (primitively wingless forms). In some crickets, such as the field cricket genus Gryllus, the copulatory act appears unique among all animals in being entirely luring, with no evidence of controlling force by the male at any stage. The female is attracted initially by the longrange calling song and then by the male's close-range courtship song and probably the fluttering touches of his antennae (Fig. 7). As in nearly all crickets, most close relatives of crickets, and most cockroaches and mayflies (the last aerially), the female mounts (or flies above) the male in the copulatory act. Apparently in correlation with the male field cricket having minimal ability to clasp the female's genital parts, the spermatophore is transferred quickly, in 15 to 90 s. The spermatophore is osmotically self-emptying, so that sperm injection occurs largely after the female dismounts from the male. In forms related to crickets, such as Tettigoniidae and Caelifera, in which males have evolved terminal claspers on the abdomen, the tactual cerci have disappeared and copulation is much lengthier. In Caelifera the mating act has evolved such that the male mounts the female, though still reaching beneath her to attach the genitalia; here, unlike Tettigoniidae, the antennae have also become much shorter. Apparently luring copulatory acts in insects have repeatedly evolved into

FIGURE 7 Adult female (left) and male (right) Phyllopalpus pulchellus, the latter with forewings in singing position. (Photograph courtesy of David H. Funk.)

acts involving significant force, but the reverse does not seem to have happened. Groups of features related to the history of insect mating acts have significance for interpreting changes in diagnostic features of major groups of insects, including cerci, antennae, genitalia, wing structure, long-range communication, and modes of pair formation.

Distinctive morphological and behavioral features of crickets, especially those related to their methods of pair formation and mating behavior, make them a pivotal group in understanding insect evolution and phylogeny.

See Also the Following Articles

Cultural Entomology • Folk Beliefs and Superstitions • Hearing • Orthoptera

Further Reading

Alexander, R. D. (1961). Aggressiveness, territoriality, and sexual behaviour in field crickets (Orthoptera: Gryllidae). Behaviour 17, 130—223. Alexander, R. D. (1966) The evolution of cricket chirps. Nat. History Mag. 75, 26-31.

Alexander, R. D. (1968). Life cycle origins, speciation, and related phenomena in crickets. Q. Rev. Biol. 43, 1-42. Alexander, R. D. (1969). Arthropods. In "Animal Communication" (R. Sebeok, ed.), 1st ed., pp. 167-215. Indiana University Press, Bloomington. Alexander, R. D., and Otte, D. (1967). The evolution of genitalia and mating behavior in crickets (Gryllidae) and other Orthoptera. University of Michigan Museum of Zoology Miscellaneous Publication No. 133, pp. 1-62.

Huber, F., Moore, T. E., and Loher, W. (eds.) (1989). "Cricket Behaviour and Neurobiology." Cornell University Press, Ithaca, NY. Otte, D. (1992). Evolution of cricket songs. J. Orthoptera Res. 1, 25-49. Otte, D. (1994). The crickets of Hawaii: Origins, systematics, and evolution. In "Publications on Orthopteran Diversity." The Orthopterists' Society, Academy of Natural Sciences, Philadelphia. Otte, D. (1994). Orthoptera species file 1: Crickets (Grylloidea). In "Publications on Orthopteran Diversity." The Orthopterists' Society, Academy of Natural Sciences, Philadelphia. Otte, D., and Alexander, R. D. (1983). The Australian crickets (Orthoptera: Gryllidae). Academy of Natural Sciences of Philadelphia Monograph No.

Otte, D. and Naskrecki, P. (1997). Orthoptera species file online at http://viceroy.eeb.uconn.edu./Orthoptera.

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