Encapsulation and melanization responses of Armigeres subalbatus against inoculated Sephadex beads

Abstract The relationship between the surface charges of foreign bodies and the responses of the mosquitoes, Armigeres subalbatus , was investigated. Sephadex beads of varying surface charges suspended in PBS (pH 5.6) were inoculated directly into the abdominal hemocoel of mosquitoes and melanization of beads was scored at 24-hr postinoculation. It was demonstrated that Ar. subalbatus melanized only positively charged beads (and to some extent neutral beads). Male and female mosquitoes responded equally to inoculated beads. In female mosquitoes, both the melanization rates and the degree of melanization were significantly greater in the thoraces than in their hemocoels. Scanning and transmission election microscopic examinations of inoculated beads revealed an amorphous coat of loosely adhering cellular debris and melanin on the surface of the beads.