Gr. Allen et al., POSTCOPULATORY MALE-BEHAVIOR, SPERM PRECEDENCE AND MULTIPLE MATING INA SOLITARY PARASITOID WASP, Animal behaviour, 48(3), 1994, pp. 635-644
Female Aphytis melinus (Hymenoptera: Aphelinidae), previously thought
to be unreceptive after their first mating, mated multiply in the held
at an incidence of at least 3.2-6.7%. In spring the adult sex ratio w
as female biased while in autumn it was male biased. Following copulat
ion, male A. melinus guard females for an average of 149 s during whic
h they display behaviour identical to that seen prior to copulation. B
ehavioural experiments using genetically marked pairs of males were se
t up to test several hypotheses concerning the adaptive significance o
f guarding and postinsemination displays. The behaviour seen during gu
arding probably keeps the female quiescent but does not influence the
fate of second-male sperm. Second males that did not guard achieved eq
ual paternity to those that did. Guarding and its associated post-copu
latory behaviour helped 'switch off' female receptivity. The percentag
e of second males that managed to achieve intromission, if attempting
to mate with a previously guarded female, dropped from 97 to 70%. Furt
hermore, males courting a previously guarded female scored significant
ly more contacts, unsuccessful mounts, time to achieve the successful
mount, wingbeats, and time in the successful pre-coital mount. Last-ma
le sperm precedence did not occur. Second males shed 30.5% of the prog
eny if the guarding male was immediately dislodged and 14.2% of the pr
ogeny if the first male was allowed to complete guarding. Thus by dela
ying rival male courtship through guarding, first male A, melinus decr
eased the chance that the female would mate again. Guarding also reduc
ed the proportion of progeny sired by a second mating male.