3.4.2. Guanine visualization
This is an indirect method based on detecting Guanine (2-amino-6-oxypurine), which is the main end product of nitrogen metabolism in mites and other arachnids. It is present only in a negligible amount in bee excretions. In this method, bee tracheae are individually homogenized and their guanine content is visualized on thin layer chromatography (TLC) plates. Since bees need to be individually tested and low level infestations may go undetected (Mozes-Koch and Gerson, 1997), this method is not usually recommended.