办事指南

How termite head-bangers outwit a fungus

点击量:   时间:2019-03-07 11:03:01

By Matt Walker TERMITES under attack from fungi send out an alarm signal warning the rest of the colony to run away. The insects signal danger by frantically waggling their heads, sending shock waves through the nest. Dampwood termites (Zooteropsis angusticollis) nest in rotting logs and trees, eating the very homes they live in. Because they can’t digest wood, friendly bacteria in their guts do this for them. “They also live in a pathogenically rich environment,” says James Traniello of Boston University. And because many individuals are packed close together, it’s easy for diseases to spread through the colony. This creates a problem. Unlike ants, which make their own antiseptics, termites can’t use chemical weapons against microbes without risk to their friendly bacteria. So they have devised an early-warning system instead. Traniello’s team made this discovery when they created an artificial nest with a central gallery divided down the middle by a wire mesh. The termites could escape via small tunnels connected to each side of the chamber. The team then infected one segment of the nest with the fungus Metarhizium anisopliae, whose spores can latch onto the termites and kill them by injecting poisons. When concentrations of the fungus were low, the termites started grooming each other to remove the spores. But when more fungus was added, they began waggling their heads in different directions. “It produces a vibration,” says Traniello. “It’s a seismic signal.” Other termites sense this signal in their legs. When fungus-ridden individuals raised the alarm, uninfected ones on the opposite side of the mesh escaped down the tunnels. “The signal conveys the information `remove yourself from this area’,” says Traniello. Termites didn’t try to escape when the researchers placed a foam mat into the nest, which dampens vibrations,