L. Passera et L. Keller, MATE AVAILABILITY AND MALE DISPERSAL IN THE ARGENTINE ANT LINEPITHEMAHUMILE (MAYR) (=IRIDOMYRMEX HUMILIS), Animal behaviour, 48(2), 1994, pp. 361-369
In the Argentine ant Linepithema humile (=Iridomyrmex humilis) only ma
les disperse whereas female sexuals (unmated winged queens) stay in th
eir mother nest where they mate. This study investigated (1) whether d
ispersing males are accepted into foreign colonies, (2) whether they c
an mate with resident female sexuals, and (3) whether the propensity o
f males to disperse is affected by the expectation of mating in their
mother nest. Field experiments demonstrated that males were accepted i
nto foreign colonies only when these colonies contained female sexuals
or queen pupae. Before and after the time of (sic) female sexuals, wo
rkers attacked and killed most of the foreign males. Laboratory experi
ments snowed that males that successfully enter foreign colonies can m
ate with resident female sexuals. The propensity of males to disperse
was significantly influenced by the presence of female sexuals in thei
r nest. Males were more likely to fly out from colonies containing no
female sexuals than from those with them. These results are consistent
with males preferentially dispersing when there is little or no oppor
tunity to mate in their mother nest. Thus there are two mating strateg
ies available for males: staying in their mother nest when an opportun
ity to mate arises or dispersing and attempting to mate in a foreign n
est when there are no female sexuals in their mother nest. This latter
behaviour could mediate gene flow between colonies and account for th
e lack of significant inbreeding previously documented in this species
.