3.3.5. Screening a large number of bees
For screening tracheae of many bees together to look for HBTM, a number of methods have been developed. Colin et al. (1979) developed the following technique.
- Place bee thoraces in a blender with water
- Grind for several seconds at 10,000 rpm 3 times to suspend the mites.
- Strain the
liquid through a screen mesh to remove larger particles and then centrifuge it
to deposit the suspended particles at the bottom of the tube, which is then
examined for mites.
The advantage of this technique is that a large number of bees (100-200) can be processed together. However, other Acarapis species such as A. dorsalis and A. externus that reside on the neck, thorax and wing bases will also be extracted with this method; see Section 2.2.
The morphological separation of these species is very time consuming. Washing bees prior to grinding was not found to be effective in removing A. externus or A. dorsalis (Lorenzen and Gary, 1986; S George, pers. obs. in New Zealand). A ‘tracheal flotation technique’ developed by Camazine (1985) reduced this risk somewhat (of mixed Acarapis species) by grinding the bee thoraces in water; however, this method would not be suitable to detect low levels of infestation.