Types and Functions of Mole Cricket (Orthoptera: Gryllotalpidae) Antennal and Palpal Sensilla
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KINGDOM : Animalia PHYLUM : Arthropoda CLASS : Insecta ORDER : Orthoptera SUBORDER : Ensifera INFRAORDER : Gryllidea SUPERFAMILY : Gryllotalpoidea FAMILY : Gryllotalpidae
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Mole crickets are members of the insect family Gryllotalpidae, in the order Orthoptera. Mole crickets are fossorial insects about 3-5 cm long as adults, with small eyes and shovel-like fore limbs highly developed for burrowing. They are adapted for underground life and are cylindrical in shape and covered with fine, dense hairs. They are present in many parts of the world.
Mole crickets have three life stages: eggs, nymphs, and adults. Most of their lives in these stages are spent underground, but adults have wings and disperse in the breeding season. They vary in their diet: some species are herbivores, mainly feeding on roots; others are omnivores, including worms and grubs in their diet; and a few are largely predatory.
Mole crickets live almost entirely below ground, digging tunnels of different kinds for the major functions of life, including feeding, escape from predators, attracting a mate (by singing), mating, and raising of young. Their digging technique is to force the soil to either side with their powerful, shovel-like fore limbs, which are broad, flattened, toothed, and heavily sclerotised. The cuticle is hardened and darkened.
Males attract mates by constructing specially shaped tunnels in which they sing. Male mole crickets sing by stridulating, always under ground. In Gryllotalpa gryllotalpa, the song is based on an almost pure tone at 3.5 kHz, loud enough to make the ground vibrate 20 cm all round the burrow; in fact, the song is unique in each species. Mole crickets stridulate like other crickets by scraping the rear edge of the left fore wing. It is used to attract females, either for mating, or for indicating favourable habitats for them to lay their eggs.
Mole crickets vary in size and appearance, but most of them are of moderate size for an insect, typically between 3.2 and 3.5cm long as adults.
The nymphs resemble the adults apart from the absence of wings and genitalia; the wing pads become larger after each successive moult.
Adults of most species of mole cricket can fly powerfully, if not with agility, but males do so infrequently. The females typically take wing soon after sunset, and are attracted to areas where males are calling, which they do for about an hour after sunset. This may be to mate, or they may be influenced by the suitability of the habitat for egg-laying, as demonstrated by the number of males present and calling in the vicinity.