What does Nosema primarily affect in bees?

Nosema is a type of microsporidian parasite that primarily infects the digestive tract of adult bees, particularly honeybees. This infection disrupts the normal functioning of the gut, leading to malabsorption of nutrients and negatively impacting the overall health of the bee. When the digestive system is compromised, it can result in various symptoms including reduced lifespan, weakened immune response, and overall colony decline. As the digestive tract is crucial for nutrient absorption and energy production, the impact on this system significantly affects the bee's ability to forage and perform other essential tasks within the hive. Thus, the focus of Nosema’s damaging effects is primarily on the digestive system of adult bees.