Colony Collapse Disorder is a well studied phenomenon relating to the decline of bee populations - has this disorder, or its equivalent, been observed in other colony-based species?
In some ways tangent to what you are asking, but many cases of classical Allée effects (i.e. a positive relationship between population growth rate and population size, see Allée & Bowen, 1932, Drake & Kramer, 2011) should be relevant, especially after your clarification in the comments.
One famous, early example of species collapse and extinction in a colony living species is the Passenger pigeon. This was an extremely common North American bird, estimated to 3-5 billion individuals, and maybe the most numerous bird species on the planet. It was heavily hunted during the 19th century (mainly by netting), which coupled to deforestation of nesting grounds led to a population crash. One of the main reasons for the rapid collapse was probably that the species was a colony nester and depended on large flocks for courtship/reproductive behaviour. This also meant that conservation measures failed when the critical situation was noticed (although hunting bans/restrictions was also weakly enforced). The few remaining wild individuals failed to breed and artificial breeding attempts also failed. The last individual died in 1914 at Cincinnati Zoological Garden (extinct in the wild from ~1900). For more information on the Passenger pigeon extinction see the wikpedia page and Encyclopedia Smithsonian.
I hope you find this example useful, even though the collapse was initiated from hunting. There are many more examples of Allée effects in colony living species that describe similar effects, but maybe not as strikingly as the Passeger pigeon case. There is a fairly recent book "Allee Effects in Ecology and Conservation" (Courchamp et al, 2008), which might be of interest to you.