Adaptive control of copulation duration by males under sperm competition in the mite, Macrocheles muscaedomesticae

Abstract

Yasui, Y., 1994. Adaptive control of copulation duration by males under sperm competition in the mite, Macrocheles muscaedomesticae. Exp. Appl. Acarol., In a manure-inhabiting predator)' mite, Macrocheles muscaedomesticae (Gamasida, Macrochelidae), when the female mates with two males, the first male takes nearly perfect fertilization priority (Yasui, 1988). The present study examined whether the first-male's sperm precedence is influenced by the copula-duration of the first and second males mating with the same female, and whether males control their copulation duration by assessing the probability that the mate has been inseminated by other males. Results ot the artificial interruption of copulation showed that sperm precedence value, P2 (the proportion of the offspring lathered by the second male), was negatively correlated with the copulation duration of the first male but positively correlated with that of the second male. There was a threshold (ca. 180-300 seconds) in the first-male' s copulation duration beyond which P2 decreased drastically; when length of the first copulation exceeded this threshold, the second males did not fertilize eggs, whereas they fertilized more than half of the eggs when the first-copulation duration was shorter than the threshold. Almost all males copulated for a longer period (average 509.8 seconds) than this threshold if the copulation duration of the previous male had not exceeded the threshold, but if it was longer than the threshold, second males had shortened their copulation (67.6 seconds). These results suggest that males are able to assess the insemination status of their mates and to .adjust their copulation duration depending on the probability of fertilizing eggs by their own sperm. A mechanistic explanation for sperm precedence (i.e., plug-Ibrmation within sperm receptive organ of the females) is propo~d.

Sperm competition games: the risk model can generate higher sperm allocation to virgin females

“…First male precedence almost total (Yasui, 1988(Yasui, , 1994 No obvious sperm limitation (Yasui, 1995), but proportion of females producing fertilized eggs declined with age and oviposition (Yasui, 1996) First male (with virgin female) copulates far longer than second male (with mated female); sperm transfer increases with copula duration (Yasui, 1994 Strong first male precedence (Gwynne, 1988) Not known More sperm to younger (mated or virgin) females than to older (virgin) females; males reluctant to mate with non-virgin females (Simmons et al, 1993). Cyrtodiopsis whitei (Diopsidae) First male precedence (Lorch et al, 1993) Remating by females may be a means of ensuring adequate stored sperm (Lorch & Chao, 2003) More sperm to virgin females (Lorch et al, 1993) Culicoides melleus (Ceratopogonidae) First male sperm precedence; P 2 very close to the numbers of sperm transferred (Linley, 1975) so probably no loading against the first male Sperm numbers decrease steadily with male age (Hinds & Linley, 1974); possibly causing sperm limitation…”

Fire millipedes obey the female sooner norm in cross mating Centrobolus (Myriapoda)

“…Male mediation of copulation duration is known in the fruitflies Drosophila melanogaster [3][4] and D. montana [5] , firefly Photinus macdermotti [6] , millipede Alloporus uncinatus [7] , mite Macrocheles muscaedomesticae [8] , spiders Hogna helluo [9] and Argiope keyserlingi [10] , praying mantid Ciulfina 2 , and soldier fly Merosargus cingulatus [11] . Female mediation is known only in the millipede Alloporus uncinatus [12] .…”

Prolonged copulation and the internal dynamics of sperm transfer in the water strider <i>Aquarius remigis</i>

“…A cohesive sperm coil in the gynatrial sac would also inhibit sperm mixing and block access of subsequent ejaculates to the vermiform appendix and the entrances to the fecundation canal and spermathecal tube. Yasui (1994) has suggested that male mites, Macrocheles muscaedomesticae, may employ a similar strategy of forming an internal "cryptic" sperm barrier to limit competition from sperm from succeeding inseminations. Andersen (1982) and Heming van Battum and Heming (1986) have suggested that the extensive musculature associated with the gynatrial complex in the Gerromorpha indicates at least some female control over the speed and extent of filling of the spermathecal tube.…”