Caste Determination in Arthropods

A defining feature in social insects is the differences between reproducing individuals and nonreproducing individuals within a colony. In many species, caste differentiation is driven by developmental processes that produce individuals with widely different phenotypes. In addition, some species of ants, bees, and termites have a polymorphic worker caste. Even within the nonreproductive individuals of a colony, developmental changes take place, and workers of highly variable sizes and shapes are produced. These caste differences are determined primarily by nutritional variation during the larval stages, which in turn influences physiological pathways that change the developmental trajectory of the larvae. Other environmental factors such as climate, social environment, and maternal effects also influence caste fate in various ways. Finally, recent research shows that genetic factors have key importance in caste determination in several species.