One Male Multiple Copulations

Make Him a Monogamy Junkie

The Monogamy Method

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Wood-feeding cockroaches in the genus Cryptocercus may be described as socially monogamous; males and females establish long-term pair bonds and live in family groups. Genetic monogamy is yet to be determined, but opportunities for extra-pair copulations are probably few. When paired with a female, males fight to exclude other males from tunnels (Ritter, 1964), and adults of both sexes in families defend against intruders (Seelinger and Seelinger, 1983). In the two copulations observed in C. punctulatus, one lasted for 34 min and the other for 42 min (Nalepa, 1988a); sneaky extra-pair copulations therefore seem unlikely. The best opportunity for cheating, if it occurs, would be after adult emergence but prior to establishment of a pair bond. Adult males and adult females each can be found alone in galleries, particularly during spring and early summer field collections (Nalepa, 1984).

Typically, males and females pair up during summer, overwinter together, and produce their sole set of offspring the following summer. Although sperm from a single copulation are presumably sufficient to fertilize these eggs (average of 73), pairs mate repeatedly over the course of their association. There is evidence of sexual activity the year before reproduction, immediately prior to oviposition, during the oviposition period, after the hatch of their oothecae, and 1 yr after the hatch of their single brood (Nalepa, 1988a). Prior to oviposition, repeated copulation may function as paternity assurance or perhaps nutrient transfer, but mating after the eggs are laid is more difficult to explain. Rodriguez-Girones and En-quist (2001) note that mating frequency is particularly high in species where males associate with females and assist them in parental duties. Superfluous copulations evolve in these pairs because females attempt to sequester male assistance and males are deprived of cues about fe male fertility. It would be of interest to determine if this pattern of repeated mating behavior occurs in other socially monogamous, wood-feeding cockroaches like Sal-ganea; these also live in family groups with long-term parental care (Matsumoto, 1987; Maekawa et al., 2005).

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