Nutrition of the mite Unionicola intermedia, Koenike and its relationship to the inflammatory response induced in its molluscan host Anodonta anatina, L.

Abstract

SummaryThe structure and staining properties of the epithelium of the midgut in Unionicola intermedia are described. Intracellular non-specific esterase, acid and alkaline phosphatase are present and confined to vacuoles. Extracellular enzymes are absent. Nymphal and adult stages of U. intermedia feed principally on the haemocytes (= amoebocytes) and mucus of their molluscan host, Anodonta anatina. Feulgen-positive material recorded from the lumen and midgut cells of the mites is believed to be derived from the nucleated haemocytes and to undergo intracellular digestion in the midgut cells. Starved mites show steadily decreasing amounts of Feulgen-positive material in the vacuoles. Haemocytes are present in large numbers below the site of attachment of the mites, their presence represents an inflammatory response, and the mite feeds on the products of this response. Large amounts of bound iron are present in the midgut cells but the origin and role of this is unknown.