Kamikaze termites blow themselves up with 'explosive' backpacks — and scientists just figured out how

Kamikaze termites in French Guiana have evolved a unique defense mechanism — carrying "rucksacks" filled with a toxic liquid that they can trigger to explode, poisoning their enemies in the process. Now, scientists have solved the mystery of how these deadly backpacks can be safely carried around then detonated on demand.

In 2012, researchers discovered that older Neocapritermes taracua worker termites are armed with blue spotted backpacks that explode when they are threatened.

The N. taracua workers have a specialized pair of glands in their abdomens that gradually secrete the enzyme blue laccase BP76 into pockets on their backs. As they age, the termites accumulate "rucksacks" filled with these blue, copper-containing blue crystals.

When faced with a threat, the aging workers rupture their bodies, mixing the enzyme with relatively benign secretions produced in their salivary glands. The result is a sticky liquid, rich in highly poisonous benzoquinones that can immobilize or kill predators.

However, researchers were puzzled by how BP76 could remain in a solid state stored on the termites' backs, while still staying primed for an instant reaction upon rupture.

The new study, published Aug. 15 in the journal Structure, solved the mystery by providing the first high-resolution crystal structure of this enzyme.

"The enzyme's three-dimensional structure reveals that BP76 employs a variety of stabilization strategies," study lead author Jana Škerlová, a researcher at the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, said in a statement.