Life

Incredible Creatures: Stories from the entomological battlefield

John Gavloski

 
Honey bees – when you spot the one that looks different than the rest, that’s the queen. (JOHN GAVLOSKI)

Honey bees – when you spot the one that looks different than the rest, that’s the queen. (JOHN GAVLOSKI)

Just like human societies, the animal world is full of conflict. For insects that live in social groups, such as ants, bees and termites, there is the need for soldier and individuals to protect the society.

This month’s Incredible Creatures we will include stories of battlefield rescues, self-sacrifice and interesting recruitment campaigns.

Ants and battlefield rescues

In Africa there is a species of ant known as the Matabele ant. These ants eat termites. Termites live in large colonies and have a soldier caste whose sole purpose is to defend the colony. So in the Matabele ants quest for food, it is inevitable that battles break out.

Each day, soldiers of Matabele ants align themselves in long columns and march toward the termites.

During these attacks, large ants (called majors) break open the nest, and smaller ants (minors) rush in to kill the termite workers. The ants then haul their dead prey back to their nest.

During a recent field expedition in Ivory Coast, a research team from Germany documented a behaviour never seen before in an insect species—rescuing behaviour. Injured nestmates are carried back to the nest, reducing combat mortality. These ants have usually lost an extremity or have termites clinging to them. They are able to recover within the nest.

The researchers learned that wounded or distressed ants cry out for help by discharging two chemical signals which are secreted through glands in the mandibles. Ant behavior is very much influenced by chemicals, and these signals compel a nearby soldier to grab its distressed nestmate and bring it back to the nest.

The study showed that injured ants that managed to return back to the nest without any help died about 32 percent of the time. But in cases where the ants were rescued, about 95 percent were able to recover and then participate in subsequent raids. These rescues help the ants to maintain the size and strength of the colony as a whole.

In spite of these battles, some termites and ants can coexist peacefully. Some species of termite form associations with certain ant species to keep away predatory ant species.

Walking bombs

Some insects are capable of exploding themselves to save their colony or brethren. In South-east Asia there is a species of ant that lives in trees known as the exploding ant (Camponotus saundersi). These ants contain a poisonous substance in their heads and in 2 large glands on the sides of their bodies.

Under threat, they will explode their head to spew the poison or rupture their bodies by squeezing their abdomen. This sprays the sticky poison in all directions to engulf the predators, immobilising them. This type of defense is called autothysis, when the animal ruptures an organ that explodes its body and kills itself in the process.

This exploding behaviour is common during territorial battles with other species of ants or predators. Weaver ants, which also live in trees and weave leaves together to make nests, are known to stalk and attack exploding ants for territory as well as to eat them.

Self-sacrifice of exploding ant workers is likely to help the colony as a whole by ensuring that the colony retains its foraging territory.

Honeybee recruitment campaigns

Honeybee (Apis mellifera) nests contain food such as honey and pollen that other animals may want to eat, and some may find the bees themselves appetizing. Defending these resources is a task that is performed by specialized workers, called guard bees.

By releasing alarm pheromones, these guard bees are able to recruit other bees to help them handle large predators. These chemicals trigger both rapid and longer-term changes in the behaviour of nearby bees, priming them for defence.

But defending the hive if you are a honeybee is not without consequences. Unlike most other bees and the queens of their own species, the stinger of worker honey bees is barbed. The barb provides one-way traction, which allows the stinger to work itself deeper into the flesh. But when they sting the stinger is torn, with the poison sac, from the end of their abdomen. This usually results in the worker bee’s death.

Because of this worker honey bees rarely sting without provocation. But when the hive is threatened, there are individuals that will put their life on the line to ensure future prosperity.

So we have seen that insects are capable of battlefield rescues, self-sacrifice and impressive recruitment campaigns. All this to help the colony thrive; without it a lot of past effort would be lost.

On this Remembrance Day, take the time to remember our soldiers who have made sacrifices so we can thrive.

Incredible Creatures is a monthly contribution to provide information on some of the common yet often not well known creatures that we share space with in Manitoba. John Gavloski is an entomologist living in Carman.