Social insects are very familiar with the threat of disease, and they employ different behaviors to protect themselves against illnesses. Not only that, but termites will exhibit different patterns of behavior based on the progression of a disease.
These defences include a range of behaviors, from pathogen avoidance, to grooming, prophylactic secretions and corpse disposals, and sometimes the collective will act against individuals in order to protect the colony. In some cases, sick members are identified rapidly and killed, in order to stop the spread of disease. However, the killings are not imprecise. Termites are able to understand how the disease manifests in an individual, and then as a collective, dynamically adjust their defences.
The behavior is not exclusive to termites either. Diseased honeybees will have a different hydrocarbon profile due to an infection, and this will trigger a reaction in other members of the nest, who will kick out the infected individual. Ants use a similar mechanism, but they are more precise in their actions. If a brood member is in the initial stages of a disease, it will be groomed, but if the disease is too advanced, the other colony members will kill it.
However, the social response of termites to disease is not quite as well documented. What we do know is that termites have three potential responses. First, they will groom the infected individual if the disease is in the initial stages. Second, if the infected termite is close to death, it is eaten. However, once it has been dead for a long period of time, the healthy colony members will no longer cannibalize it. Instead, they will defecate on the corpse, and then bury it. Researchers have also observed that live individuals are sometimes buried as well.
What has been unclear about this behavior until recently is when the termites choose to go from grooming to cannibalism. A new study has found that each behavior is designed to prevent the disease from reaching the next stage in its life cycle. For example, grooming is used before certain infectious disease pathogens or fungi can germinate. The termites are able to safely remove the pathogen and kill it in their stomach. Once the infection reaches the internal organism of a termite, grooming is no longer effective, and the infected termite can no longer be saved. To make matters worse, if it is left alive, it will spread disease among other members. As such, the corpse is consumed where once again, the pathogen reaches the stomach of the cannibalistic termites and it is neutralized.
As we can see, social insects and termites in particular do not take any chances with diseases, but they are not excessive either with their defense mechanisms. They will first try to “cure” the infected member, before moving on to more drastic measures.
