SOLDIER AND MALE OF AN EUSOCIAL APHID COLOPHINA-ARMA LACK ENDOSYMBIONT - IMPLICATIONS FOR PHYSIOLOGICAL AND EVOLUTIONARY INTERACTION BETWEEN HOST AND SYMBIONT

Distinct morphs, including the soldier and male, of an eusocial aphid Colophina arma were studied with special attention to their endosymbiotic system, employing antiserum raised against symbionin, an aphid endosymbiont-specific protein, as a probe. We estimated the amount of symbionin in the different morphs by immunoblotting, which suggested that the soldier and male lacked the endosymbiont while all the reproductive female morphs examined were rich in it. Immunohistochemical studies on their internal structure confirmed that the soldier and male lack the endosymbiont entirely. It was also revealed that, in the soldier, not only is the endosymbiotic system lacking, but the reproductive system was not found and was replaced by the well-developed fat body cells. Based on these findings, we discuss the differentiation of the soldier, its specialized physiology and evolutionary implications for host-symbiont interactions.