Complex sentence: Since "Eg. imperialis" is not a social bee--and therefore, lacking a worker caste--the nest is constructed communally, in the sense that it is the resultant product of a combined effort of many generations of "selfish" individual behavior.
Split into simpler sentences: Since "Eg. imperialis" is not a social bee and lacks a worker cast, the nest is constructed communally. A nest is the product of a combined effort of many generations of "selfish" individual behavior.