Can termites eat bamboo

No question about it, termites are natural architects. They build slender towers as high as a house and extensive hills with ingenious ventilation systems from earth, excrement and water. But they have little respect for man-made architecture. They devour sleepers, studs and rafters, because wood is at the top of their menu. The vegetarian insects are also said to have attacked sugar cane, tea and coffee plantations as well as bank notes and court files. The economic damage worldwide amounts to billions of euros annually.

As an antidote, poisonous, and in some countries also carcinogenic insecticides, which can accumulate in nature, are generally used.

Dino McMahon, biologist at the Federal Institute for Materials Research and Testing (BAM) and professor at the Free University of Berlin, is therefore testing an environmentally friendly alternative. The active ingredient is based on the sugar-like substance "glucono-1,5-lactone" (GDL), which is also found in various foods and baking powder as an additive E 575. The agent weakens the termites' defenses against bacteria and fungi and has already proven itself in initial studies. "If you spray a mixture of GDL and a fungus on infected wood, you can destroy entire colonies," says McMahon. The researchers use fungi of the genus Metarhizium, which are found in practically all soils in the world. And for their tests they can fall back on a kind of termite zoo in the BAM basement, where millions of whitish, winged representatives of the almost 30 voracious species cavort in boxes filled with earth and wood.

Liquid nitrogen or electric shocks to combat

There are around 3000 termite species worldwide, most of which either live in nests of the earth or, in the case of the so-called dry wood termites, live directly in the wood. They are primarily at home in subtropical and tropical regions, but also in the USA and in the Mediterranean countries. In Germany they only give a few guest appearances. "Despite climate change, termites cannot be expected to become a permanent part of the fauna here in the near future," says McMahon's colleague Rüdiger Plarre. A few days of frost were enough to destroy them.

Only in Hamburg-Altona were the insects able to establish themselves for many decades. They had probably come into the country with firewood from North America. A district heating network, poorly insulated underground, provided the warmth necessary for survival. With poison bait and pipe renovations, the stock was finally put to an end in 2010. It is true that termites occasionally come in as stowaways, for example in exotic plants or tropical wood furniture. "The vast majority of reports of alleged termite sightings are ants," says Plarre.

The list of possible antidotes is long. The most common are insecticides and poison baits. In the case of a localized infestation by dry wood termites, the insects can also be fought with hot air or with liquid nitrogen that is almost minus 200 degrees Celsius. However, the infested rooms usually have to be cleared for this. Some specialist companies also use microwave technology or electric shocks for heating. There is also a remedy against termites in untreated wood that paralyzes digestive enzymes. The insects then starve to death with full bodies.

The substance blocks communication among the social insects

American researchers reported in the journal as early as 2009 PNASthat the lactone GDL could also be used as an antitermit agent. The substance blocks a protein that the insects build into their nests and which, like a sensor, detects pathogenic germs, shreds them and releases them as a kind of blueprint. In this way, the termites can sharpen their immune system in good time. As McMahon's tests show, the administration of GDL also leads to the fact that social warning mechanisms no longer work. "Termites are very social insects. Among other things, when they feed each other, they exchange information about where there is a threat to them and where infected nest-dwellers are," explains the researcher. Then they clean the skin and shell of the infected conspecifics or they eat them to prevent the infection from spreading. If GDL was sprayed, such actions were observed less often.

Next, Dino McMahon wants to administer the agent in further series of tests to groups of 1000 termites each and determine the perfect dose for use. "We brought a couple of wild termite colonies from France for the experiments. There aren't even enough animals here for such a large project," says the biologist.