Pheromonostasis is not directly associated with post-mating sperm dynamics in Choristoneura fumiferana and C. rosaceana females.
In Lepidoptera, a number of humoral and neural cues are involved in post-mating pheromonostasis, including the presence of sperm in the spermatheca. However, as there are two types of sperm, apyrene and eupyrene, they may play different roles in pheromonostasis, an aspect not considered in previous studies. As a first step to examine this possibility, we determined the quantity of sperm transferred by the male at the time of mating and the temporal migration of both sperm types from the bursa copulatrix to the spermatheca in the spruce budworm, Choristoneura fumiferana, and the obliquebanded leafroller, C. rosaceana. While the mass of the ejaculate was positively correlated to male body mass, there was no relation between ejaculate mass and sperm numbers. In both species, the migration of the two sperm types was asynchronous, with the apyrene sperm migrating before the eupyrene type. There were, however, some interspecific temporal differences in the migration of both sperm types. Eupyrene sperm would not serve as a direct signal for pheromonostasis in either species as it does not reach the spermatheca for at least 7 h while the neural message for pheromonostasis in both tortricids occurs within 3 h of mating. Given the time apyrene sperm arrives in the spermatheca (between 3 and 5 h post-mating), it could serve as a direct cue for pheromonostasis in C. fumiferana but not in C. rosaceana. However, considering that these two Choristoneura species have similar pheromone physiologies, it seems somewhat unlikely that apyrene sperm would be involved in one species and not the other.
Marcotte
M
M
Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 3800, Sainte-Foy, Québec, Canada G1V 4C7.
Delisle
J
J
McNeil
J N
JN
D000818:Animals; D005260:Female; D007915:Lepidoptera / Q000502:physiology*; D008297:Male; D010675:Pheromones / Q000502:physiology*; D012098:Reproduction / Q000502:physiology; D013045:Species Specificity; D013076:Sperm Count; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*
D010675:Pheromones