1986] Peeters & Crewe — Male biology in Ophthalmopone 281 
nest. The substantial variations in the percentages of gamergates 
present in different nests at any one time of the year (Peeters and 
Crewe, 1985) suggest that the number of male visits to a particular 
nest is irregular. Some nests may be located more often than others, 
and consequently varying numbers of young workers become 
mated. In polydomous colonies such as these, gamergates can be 
transferred between nests and, hence, a colony should survive from 
year to year as long as one of its nests is visited by males. 
The exit of males from their natal nests is not coordinated, and 
they disperse over a period of a few weeks. This is different to the 
situation in queenright species where the emergence of all the male 
and female reproductives is synchronized in time (e.g. in Campono- 
tus herculeanus, through the release of a mandibular gland phero- 
mone by the males; see Holldobler and Bartz, 1985). Dispersal is 
then often associated with the initiation of new nests, which must 
occur during optimal environmental conditions (e.g. after rain). In 
contrast, copulation in O. berthoudi is not followed by independent 
colony foundation by the mated workers, because colonies repro- 
duce by fission (Peeters, 1984). Thus it is no longer selectively 
advantageous for males to disperse simultaneously in response to a 
specific environmental cue. However, males continue to be pro- 
duced only during a short period of the year. Unmated workers 
show no ovarian activity in O. berthoudi, and haploid eggs are laid 
exclusively by gamergates (Peeters and Crewe, 1985). Egg fertiliza- 
tion is thus a voluntary act by the mated workers, and males are 
produced following the first summer rains. Sperm exhaustion is 
unlikely since individual gamergates lay relatively few eggs during 
their lifetime. It is not known whether all the gamergates in a nest 
produce haploid eggs; the inter-nest transfer of male adults and 
pupae would make this hard to determine. 
The importance of chemical attractants during nest location 
remains unclear. In Leptogenys ocellifera, a ponerine with ergatoid 
queens, dispersing males search for the chemical trails that lead 
from the nests into the surroundings (Maschwitz and Muhlenberg, 
1975), and males of Megaponera foe tens follow trails laid by 
workers during raids on termite nests (Longhurst and Howse, 1979). 
This is impossible in O. berthoudi because continuous trails are not 
laid. There is evidence that discrete scent marks are deposited on the 
substrate by inexperienced foragers (Peeters and Crewe, MS), but 
this may be of no use to males. It is conceivable that the pygidial 
