re in social insect

Reviewthat the majority of social insect species are characterized by ‘strict ’ environmental caste determination (ECD). Rather, it appears that caste determination systems vary along a continuum from ECD to genetic caste determi-nation (GCD), where environmental factors no longer affect an individual’s caste fate. We describe the proximate basis for genotype–caste associations in the species where genetic effects on castes are known to occur, and evaluate mechanisms generating and maintaining variation in caste predisposition. Although we focus solely on the bifur-cation between royals and workers, most of the presented arguments should also apply to differentiation among worker castes, such as that found between specialized soldiers and nurses. ducted in the western honey bee (Apis mellifera), a species generally recognized as having strict ECD. Independent experiments have revealed that a large amount of food, or a protein rich diet, are a necessary and sufficient condition for the development of new queens [9–12]. Queen devel-opment can also be induced by down-regulation of a DNA Glossary Environmental caste determination (ECD): a system of queen and worker differentiation that is determined by environmental stimuli and largely insensitive to genetic factors (phenotypic plasticity). Genetic caste determination (GCD): a system of queen and worker differentia-tion where an individual’s genotype predicts its caste. Environmental stimuli do not affect the caste fate of a given genotype although they might determine which set of genotypes are raised. Intermorphic queens: reproductive females morphologically intermediate between a typical queen and a typical worker. Queen traits include, for example, the presence of a spermatheca and large ovaries, worker traits include the lack of wings and associated thoracic structures and the absence (or reduction) of ocelli