A VISUAL TEST FOR NOSEMA-APIS INFECTIONS IN HONEY-BEES

A simple test for diagnosing Nosema apis infections in honey bees, whi ch does not require a microscope, is described. Bee abdomens are crush ed in water in plastic 1.5 ml microcentrifuge tubes, nigrosin stain is added and the tube left to stand vertically overnight. Centrifugation of the tubes eliminates the need for an overnight wait. The nigrosin stains any bee tissues and most pollen a dark blue/black and the N. ap is spores settle to form a pale grey, unstained pellet at the bottom o f the tube. Eight million or more spores per bee can be detected (P < 0.05) and the size of the pellet gives an indication of the magnitude of the spore load. Pooled samples of bees crushed in a plastic bag may be similarly assessed, although some accuracy is lost.