- Mating within the nest.
- Limited dispersal of mated queens.
- Coexistence of multiple queens in the same nest (i.e. polygyny).
- Rare, patchy populations.
- Reduced body size, mouth-parts, antennal segmentation and
propodeal spines. - Reduced thickness, pigmentation and sculpturing of the exoskeleton.
- Reduced nervous and exocrine systems.
10.Broadening of petiole and postpetiole.
11.Enhanced attractiveness to hosts, probably chemically mediated and
indicated by frequent licking and grooming by the hosts.
Behavioural Mechanisms
The behavioural mechanisms associated with the adaptations of various
organisms for a parasitic existence can be summarized using Doutt’s
(1964) four sequential steps of host selection: host habitat finding, host
finding, host acceptance and host suitability. This framework can be
applied to socially parasitic social insects, but most studies of the
behavioural ecology of these insects have focused on the interactions that
occur between parasite and host once the parasite has located the host
nest and is attempting to establish a parasitic association. At this point,
the first three steps in Doutt’s sequence are already completed and only
host suitability remains to be resolved. None the less, this final step is of
considerable interest, since it involves direct interactions between the
parasite and the host and is the point at which the parasite must overcome
host defences if it is to be successful.Host-habitat finding
Locating and colonizing host populations is undoubtedly an important
aspect of the biology of actively dispersing social parasites, but very little
research has addressed this issue directly. In general, socially parasitic
social insects tend to be relatively rare, compared with their hosts, and
many are known from only a limited number of records and from very
localized and sometimes very patchy populations (Wilson, 1963, 1971;
Hölldobler and Wilson, 1990). Thus, the known range of many social
parasites appears to be a small subset of the range of their host species.
Moreover, in many social parasites, mating appears to occur within the
nest and dispersal is sometimes very limited. Indeed, some social
parasites have evolved to become wingless and have thereby lost the
ability for long-range dispersal (Wilson, 1963, 1971; Buschinger and
Heinze, 1992). None the less, in those species that do retain wings and
actively disperse from the vicinity of the parental nest, the ability to locate
suitable habitat containing host colonies is clearly essential to survival.324 R.J. Stuart