|Mating in Insects
Mating procedures may be divided into four general stages, varying, of course, with the kind of insect.
Locating and recognizing mates.
Often in populations of insects, males of the species emerge first as adults, and thus are available for mating when the females emerge. The usual example of this strategy is in the genus Opifex, a mosquito group in New Zealand, where males immediately mate with the female as she emerges from her pupal shell. Finding and recognizing mates is usually achieved by chemical attractants in the air (called pheromones), appearing at the same food, sometimes by sound, and uncommonly by light flashes (as in fireflies) or flashing of colors. Sex-attractant pheromones are produced by female moths and perceived in the air by the antennae of males of the species. The male silk moth, by current estimates, can detect a few hundred pheromone molecules among 25 quintillion molecules, an incredible accomplishment. Male mosquitoes locate females for mating by responding to the humming sound made by the vibrating wings of the females. Many kinds of insects, including flies, beetles, wasps, bees, and butterflies are known to congregate at locations termed leks, where there is no food, water or beneficial resource other than individuals of the same species. These leks are simply a place to locate mates. As might be expected, the different ways in which insect sexes locate and recognize each other are extremely numerous because there are so many insect species.
In some insect species, there are no signs of rituals preceding mating. Most insects, however, engage in routines that are uniquely characteristic of the species. Females are often stroked by the males, by use of legs or antennae. Dance patterns may be performed, wings may be fluttered or moved in circles, or short flights may occur. Specific rituals have developed through evolution and must be precise routines. Courtship rituals of insects are extremely numerous.
Internal fertilization by insertion of the male intromittent organ into the female genital tract for deposition of sperm is the usual method of copulation. There are exceptions, of course, and the most dramatic is perhaps the bedbug, where males actually pierce the body cavity of the female with their penis to deposit sperm. Springtails (Order Collembola) are exceptional also in that the male produces spermatophores and places them in a circle around the female. The male then performs a courtship dance, encouraging the female to cross the circle. The female then grasps one droplet with her genital opening, which leads to fertilization. Mating may occur on the wing, the primary examples being the "lovebugs" of the southern states, which are actually flies, and members of the insect order Odonata (dragonflies and damselflies).
After mating, there is danger for some males. Praying mantis females sometimes eat their mates, starting with the head. The male mantis continues mating even though his head is gone! After mating, however, the main concern is the oviposition of eggs in a place that does not expose them to predation. Once the eggs are deposited, the adult females leave the scene. Methods and patterns of laying eggs are extremely varied, generally peculiar to the species. Commonly, females deposit their eggs near, on, or in the food of the immature stage.
Beebe, W. 1947. "Notes on the hercules beetle, Dynastes hercules (Linn.), at Rancho Grande, Venezuela, with special references to combat behavior." Zoologica, 32: 09-116.
Dambach, C. A. and Good, E. 1943. "Life hisory and habits of the cicada killer in Ohio." The Ohio Journal of Science, 43: 32-41.
Davey, K. G. 1965. Reproduction in the insects. Freeman, San Francisco.
Smith, R. L., ed. 1984. Sperm Competition and the Evolution of Animal Mating Systems. Academic Press, New York.
Thornhill, R. and Alcock, J. 1983. The Evolution of Insect Mating Systems. Harvard University Press, Cambridge, Massachusetts.
Waldbauer, Gilbert. 1996. Insects Through the Seasons. Harvard University Press, Cambridge, Massachusetts.
Prepared by the Department of Systematic Biology, Entomology Section,
Information Sheet Number 146
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