Lowered+immune+system

**Lowered Immune System**

The weakening of the immune system leads to the facilitated spread of viruses, infections and diseases throughout the colony (Elizabeth Macarthur Agriculture Institute 2003; Navajas et al. 2008). An immune system fights off infections, germs and microorganisms to help protect the bee. More information about the immune system can be found at []. This site is for the human immune system, but it will give you a general idea of what an immune system is.

One of the many differences between the immune system of a honey bee and a human is the bee's evolution of strategies to combat disease through grooming and hygiene practices. This is a common occurrence in social insect colonies, where thousands of individuals live in small, high density areas. Bees also live in close proximity to their food source, making them even more vulnerable to disease and viruses (Evans et al. 2006). 

When the immune system fails to fight off viruses and diseases this can be life threatening for the bee. One of the effects that viruses can have on honey bees is ‘disfigured, small adults with deformed legs and wings’ (Navajas et al. 2008). One virus known to be spread by the mites is the Deformed Wing Virus (DWV) (Navajas et al. 2008; Rosenkranz et al. 2010).

**. ** Lowered immune systems are a factor related to Colony Collapse Disorder.

= How does the mite lower the honey bee's immune system? =

The //Varroa// mites use their mouth parts to pierce the soft tissue of the bee, which allows them to draw and consume the bee's blood (Elizabeth Macarthur Agriculture Institute 2003). This then makes the bee more vulnerable to infections, viruses and diseases, and as the immune system fights these off it can become weaker. It is well known that viruses can be transferred between the mite and bee through this process (Yue & Genersch).

.  This image shows an adult worker honey bee that has been infested by //Varroa// mites. Source: Agricultural Research 2004.

©Kirsty Pearson 2010