Determinants of sperm precedence in a noctuid mothHeliothis virescens: a role for male age

Abstract

Summary 1. Females of the noctuid moth Heliothis virescens F. mate more than once. Thus, sperm from two or more males normally compete for fertilisations within the female reproductive tract. The eggs are typically fertilised by sperm from only one male, either the female's last mate or an earlier mate. Twice‐mated females store only one ejaculate's worth of fertilising sperm (eupyrene) but nearly two ejaculates' worth of a nonfertilising sperm morph (apyrene), which is thought to play a role in sperm competition. 2. The mechanism of sperm use in H. virescens was investigated by examining factors that vary with paternity, which was assigned based on allozyme variation. The factors included male and female body masses and ages, male genital characters, the size of the sperm package, and the number of sperm stored by the female. 3. One male typically gained sperm precedence; this was nearly twice as likely to be the second male as it was to be the first. Two factors were found to vary significantly with paternity: female mass and male age. The second male to mate was more likely to gain sperm precedence if the female was larger and if the male was older than the female's first mate. 4. The significance of male age and female mass to several hypothetical models of the mechanism of sperm use is discussed.

Paternity Allocation in a Mutant Heliothis virescens1Colony

“…These results are in contrast to previous studies in this system that showed the second (last) male generally obtained precedence over the first (Flint and Kressin 1968, Pair et al 1977, LaMunyon 2001. This study shows the importance of long-term observations to assess paternity allocation.…”

“…The first two scenarios have been called 'sperm precedence' (Svärd andMcNeil 1994, Simmons 2001). The third scenario leads to multiple paternity (LaMunyon 2001, Simmons 2005.…”

“…Previous research on multiple-mated tobacco budworm females describes how paternity corresponds primarily to one male with a brief mixing of paternities when a subsequent male copulates with a female (Flint and Kressin 1968, Pair et al 1977, LaMunyon 2001. Here we used a phenotypic marker in conjunction with staged matings to revisit the frequency at which sperm precedence occurs.…”

Experimental evidence for interspecific directional selection on moth pheromone communication

“…Sperm competition and sperm precedence have been measured in Hv as well (72)(73)(74)(75)(76). Sperm precedence typically occurs, although the eggs are not always fertilized by sperm from the last male to mate but by sperm from the oldest male (74).…”

Age- and size-dependent mating performance and fertility in a pelagic copepod, Temora longicornis

“…The females have 2 genital openings, and it is believed that additional spermatophores cannot be connected to the genital openings because they are full. We modified existing DAPI protocols used for insects, bacteria and blue-green algae to stain the spermatozoa before counting (Porter & Feig 1980, LaMunyon 2001. The females were killed by freezing at −18°C.…”