4.4.4. Chemical stabilizers
There are a number of chemicals that help prevent RNA degradation. For these to work, they have to penetrate the bee exoskeleton and get into the tissues. They are therefore more useful for extracted tissues, eggs and larvae and less useful for adult bees. There are two types of chemical preservation: salts (in solution or impregnated on collection cards) and organic solvents (usually alcohol). Solvents penetrate the exoskeleton better than salt solutions and are more suitable for adult bees. A large excess (>5-fold by weight) should be used to make sure the chemical’s concentration in the tissues is high enough to inhibit the nucleases. Various solutions and how to use them are described in the BEEBOOK paper on molecular methods (Evans et al., 2013).