Kamikaze termites have evolved a unique mechanism: carrying backpacks filled with toxic liquid 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. The termites were first spotted in 2012, armed with blue spotted backpacks they exploded when threatened. The insects have a specialized pair of glands in their abdomens that gradually secrete the enzyme blue lacasse BP76 into pockets on their backs. As they age, the termites accumulate pockets (backpacks) filled with these blue, copper-containing 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 that’s rich in highly poisonous benaoquinones that can immobile or kill predators. Researchers were puzzled as to how the backpacks could remain in a solid state on the termites’ backs, while staying primed for an instant reaction upon rupture. Scientists have now solved the mystery. The enzyme is tightly folded, much like folding a piece of paper into a compact shape, which helps it resist degradation over time. Another layer of protection comes from sugar molecules that are attached to the protein, forming a protective shield that further stabilizes it. There’s a strong chemical bond between two amino acids — lysine and cysteine — that acts like a special locking mechanism, ensuring that the enzyme retains its shape and remains fully functional, ready to be deployed in an instant when the termite needs to defend its colony. With their exploding backpacks, older workers may specialize in providing a final, deadly act to defend the colony.
