A male view on reproductive diapause, or coadaption of male reproductive strategies to diapause in female insects

M. P. Pener

Dept. of Cell and Animal Biology, The Hebrew Univ., 91904 Jerusalem, Israel

Reproductive adult diapause (including quiescence) in male insects has been characterized by many different traits in different species, but it should be defined as a reversible state of inability of the male to inseminate receptive females. Male reproductive strategy is under selection pressure towards a balance between maximum chances of fertilization of the females' eggs and minimum waste of energy, as well as minimum predation risk. Therefore, in species with a female reproductive diapause, male reproductive strategy must be adapted to female diapause and diapause-related female and male strategies must be coadapted. In a previous review (Pener, 1992, Chronobiology International, 9:102-113) three types of such coadapted reproductive strategies were recognized: (1). The female is receptive in the early part of her diapause when copulation occurs. The male dies shortly after mating and the female stores the sperm to fertilize the eggs that develop after female diapause is terminated. (2). The female is receptive during diapause; oocyte development is arrested, but mating occurs and the stored sperm fertilizes the eggs after female diapause is ended. Reproductive diapause may not occur in the male, or it may exist in a portion of the males, and the actual situation in a species may reflect some balance in sperm precedence in that species. (3). The female is refractory during diapause and the male exhibits reproductive diapause. The diapause is controlled by similar environmental cues and the same endocrine mechanism in both sexes, but male diapause usually terminates before female diapause. Recent data in the literature indicate that strategy no. 3 may be quite widespread and there are intermediate cases between strategies no. 2 and no. 3. Moreover, some further strategies may exist. Male diapause is under two antagonistic selection pressure; a male should not waste energy to court refractory females, but should be ready to mate as soon as the female becomes receptive.

Index terms: reproductive diapause, male, coadaptations, environmental cues.

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