Spooky Insect Facts Unveil How Cannibalism Is All About Recycling
By Thomas Chouvenc, PhD, Assistant Professor of Entomology
DAVIE, FL- Insects can be a great source of material for spookiness during this Halloween time of the year. In addition to your usual spider or creepy-crawler, there are many other creatures to draw from for an instant horror story. A classic example is the zombie-ant, where a fungal parasite manipulates its ant host and turns it into a zombie.
Another example is the parasitoid wasp. As the larvae eat their host from the inside, they reap it apart while keeping the host alive the entire time.
Did you know that there are burying beetles that lay their eggs on an animal carcass and rear their young in the decomposing flesh? Yes, insects can be quite a source for gore.
Let’s not forget the cannibalistic insect societies such as termites. Termites are actually cannibals, and on top of bringing you the horror of losing part of your house to their extensive appetite for wood, they are practicing total cannibalism of their dead.
Termites have evolved for millions of years chewing on wood, which are carbon-rich but nitrogen-poor diets. Termite colonies need the carbon from the wood to fuel their metabolism, but they need a lot of nitrogen to grow the colony. Nitrogen is a challenge for termites to access because wood is so poor in nitrogen. Yet, they have perfected a recycling strategy to conserve nitrogen over evolutionary time and that is cannibalism.
In termites, cannibalism allows them to recycle nitrogen within the colony, to the point that if any member of the group is sick, moribund or dead, it will be immediately consumed by its brothers and sisters. It not only prevents disease from spreading, it saves and reutilizes precious resources by bringing it back into the society.
It was previously assumed that termite colonies with no wood access would rely on cannibalism of some of their own to enhance their chance of survival. However, it seems that termites don’t demonstrate this survival strategy according to a recent study published by Thomas Chouvenc, an assistant professor at the Fort Lauderdale Research and Education Center of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS). The study showed that in termite colonies, eggs and larvae are consumed first, followed by young workers, leaving at the end only older workers, and the king and queen. Chouvenc argues that mortality was driven by stressed individuals that failed to molt properly as they starved, and were automatically cannibalized by their nestmates, because of the inherent biological rules for recycling nitrogen.
However, Chouvenc argues that cannibalism does not provide much fuel to the cannibal, and therefore does not really provide much help to increase the survivorship of the group. Therefore, while termites are amazing recyclers, they are poor at managing food storage solutions, just like bees do with honey. Instead, their strategy is to keep feeding on your house, so they don’t ever run out of food.
Now you know that if you have termites, your home is being devoured by a horde of cannibals…
The study was published this week in Insectes Sociaux, the journal of the International Union for the Study of Social Insects (IUSSI), It covers the various aspects of the biology and evolution of social insects and other pre-social arthropods.
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