Parts to examine

Although molecular evidence of N. ceranae DNA in other tissues than the ventriculus have been described, no spore production has been demonstrated outside the epithelial cells of the ventriculus for either of the two microsporidians concerned (Chen et al., 2009; Bourgeois et al., 2012). Thus, for spore counts, the ventriculus is ideal since the amount of surplus debris is low compared to using the entire abdomen or the whole bee in mash preparations.

Dissecting the ventriculus:

With some training, it is easy to pull the ventriculus out from CO2 immobilized bees (see the section on anesthetising bees in the BEEBOOK paper on miscellaneous research methods (Human et al., 2013)) using forceps.

 Grip over the A7 abdominal dorsal and ventral segments with the forceps

  1. Hold the abdomen in the other hand,
  2. Slowly pull apart; the posterior portion of the alimentary canal comes out, sometimes with, sometimes without, the honey sac attached to the anterior end of the ventriculus (Fig. 1).

 It should be noted that this procedure is difficult to perform on bees that have been frozen and thawed.

Because of the labour involved, the use of the ventriculus for spore counts is generally more suitable for laboratory cage experiments. For field investigations of colonies, it is recommended to use samples of whole bees, or abdomens of adult bees.

Fig. 1. Posterior section of the worker honey bee alimentary canal and sting apparatus: A = sting apparatus; B = rectum; C = small intestine; and D = ventriculus (midgut). Line = 2 mm (Dade, 2009).

 Figure 1