center for food safety
The convergence in almond groves of so many commercial bees from all over the country creates a hotbed of viruses and pathogens that can spread to many hives. The varroa destructor mite carries at least 19 different bee viruses and diseases, causing major impacts on bee colonies. Parasitic phorid flies are another problem, and highly contagious infections also pose significant threats. The intestinal fungus nosema ceranae, for example, prevents bees from absorbing nutrition, resulting in starvation.