"Ropiness" of brood

Introduction to the ropiness test

Larvae and pupae infected with AFB display a characteristic “ropiness” when a small stick is used to slightly stir the diseased tissue in the cell and then the stick is slowly removed (Fig. 24).

The ropiness is thought to be caused by the presence of long chains of the vegetative stage of AFB bacteria intertwining and producing an elastic, binding effect.

Figure 29: An AFB infected larva being roped out with a matchstick

The ropiness test is a common technique used to diagnose American foulbrood (for a description of how to accurately perform this test, go to the ropiness test , within the Inspection and Diagnosis section.

A positive ropiness test will almost always correctly diagnose AFB.

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