Human vs. Termite

The new battle plan against termites

Termites have been prospering for 300 millennia.
Today's scientists are using their culture against them.

Termites have been winning for a long time.

When the first colonies developed almost 300 million years ago, dinosaurs were just starting their domination of Earth. From those first societies, termites have infiltrated every part of Earth not covered by ice. The dinosaurs are gone, but termites are still thriving.

Unlike their cousin the cockroach, which prefers a solitary existence, termites developed complex social bonds and behaviors that their colonies possess today. As a highly organized team of up to one million hungry members that will eat almost anything made of cellulose, they can systematically devastate an entire forest.

Things only got better when the newcomer humans organized themselves into cities, all of that tasty food so conveniently brought together in one place.

Instead of retreating before the rise of civilization, a heartbeat in termite history, termites have lived well off human habitations, leaving people the perennial losers with billions of dollars of damage each year. Despite advances in chemistry, physics and atomic warfare, humans continue to look for ways to fully get the upper hand.

The contest may yet swing in favor of bipeds who are beginning to think beyond pesticides and employ knowledge of termite behavior and organization against these pests. Talk about fighting dirty.

Richard Houseman, an associate professor of entomology, is an expert in the social behavior of termites. He has written more than 40 publications advising homeowners how to cope with household insects. He created pesticide application training programs and is a consultant to the biggest companies in the field.

Houseman authored more than a dozen research papers on buggy subjects, including how termite colonies divvy up resources, forage for food, handle tunneling decisions and disperse soldier termites to conduct war on competitors. He also researched how urban and forest termite communities differ.

Many of his research topics help answer one basic question: How does a primitive insect keep getting the better of human beings, self-considered the most evolved species on earth?

The general answer lies in understanding how termite societies efficiently integrate the actions of millions into one seemingly coordinated plan. Unlike a robot mindlessly controlled from a central authority, each termite can respond individually to stimuli it encounters according to instinctive programming that maximizes the collective good of the colony rather than any individual. This gives the collective incredible flexibility in almost any environment.

Termites are stimulus-response critters, Houseman said. Each individual acts instinctively according to a reflex response. For example, when a worker termite finds an unwanted opening in a tunnel, it begins a chain of behaviors eventually involving hundreds or thousands of others. It immediately drops a bit of anal cement to mark the spot and serve as a gluey base for repairs then excitedly runs down the tunnel leaving a trail behind to collect soil particles to place on the cement. Along the way, the worker head butts other termites who become excited, follow the trail back to the opening, and duplicate the response of the first termite. Thousands of individual responses to these simple stimuli create a soil conveyor belt until the hole has been filled.

This individual-yet-communal response gives the termite awesome impact few other insects can conjure. Termites combine the best of complex individual and group action in foraging, feeding, reproduction and defense. Given patience, which termites have in abundance, their integrated populations can prevail over competing insect threats and thrive amidst modern human civilization.

Another reason that termites have been successful is that they have pursued a fundamentally different evolutionary strategy. Humans think of adaptation as a series of upgrades leading to bigger brains and more efficient physiques. In contrast, termites have held onto their primitive bodies, virtually unchanged for millions of years, while evolving ever more intricate systems of collective behavior.

If the termite has evolved individually, it has done so in a way that humans would consider backward. For the collective good, they are incredibly specialized in their jobs. In fact, individual termites can no longer live alone outside the colony. They are totally dependent on the collective for their survival.

Understanding these unique specializations may lead to improved methods of killing them.

New attack plans

Current anti-termite strategy involves drenching the soil around an infested home with termiticide, a pesticide specifically made to create a barrier that repels termites.

This method is reliable and effective, but public concern about the risks of large quantities of these chemicals has scientists looking for improved methods, Houseman said.

Houseman and his colleagues, with an understanding of termite behavior, are targeting termicides only to locations where termites are known to hang out, an area close to food that has consistent favorable moisture and temperature. The environmental impact is lessened because chemicals aren't introduced to areas where termites never go.

The scientists are also developing a new generation of termiticides that kill rather than repel. These chemicals are not detectable by the termites, so colonies unknowingly pick up a lethal dose and die after entering treated soils.

Another approach targets a termite's favorite place, the suburban mulch bed. So far, however, developing a termiticide-treated mulch has proven difficult since the sun's ultraviolet rays and microbial decomposition break down these compounds quickly.

Likewise ineffective so far is an idea of finding a mulch inherently repugnant to the bugs. For this, Houseman and his team devised two termite taste tests. These tests showed that Missouri termites prefer oak and pine needles over cypress, cedar and bark. Unfortunately, the tests also showed that termites aren't that picky and will dine on their second and third choices if the choice stuff isn't around.

Back in the lab, the scientists are looking at a promising and highly-targeted control method called termite baiting. Here, a hormone fatal to termites in high concentrations, but safe to humans, is embedded in a cellulose substrate and placed underground near the colony. When eaten, this hormone disrupts the termite's frequent molting process by stopping it from producing a new exoskeleton. Because termites share their food, successfully feeding only a few members can imperil the entire colony. This method is safe for humans, who have no exoskeleton to lose, and puts even fewer chemicals into the environment.

A higher-tech version of this involves introducing a knockout gene to the colony via bait food. Still very experimental and not ready for product testing, this technology is designed to disrupt the production of essential proteins within the cells of termites that eat the bait. The termite's life processes are disrupted and it gets sick and dies.

Still another idea, also in an early research stage, involves injecting a lethal fungus into the colony to make termites deathly sick. So far, this has worked only in controlled conditions because termites are particularly keen in grooming their nestmates, removing the fungus from each other and disposing of it with other waste.

Confusing the termites with food

Understanding termites' feeding habits presents a new and exciting opportunity for termite killers, Houseman said. Termites constantly feed each other in two ways. The first is a mouth-to-mouth method where one individual taps the mouthparts of a nestmate to ask for a regurgitated meal. The other food-sharing method involves the hungry termite tapping on the other end of a nestmate, who provides a fecal meal.

This second form of feeding is a critical action as the feces contain protozoa from the digestive tract that termites must occasionally replenish in order to digest the cellulose that they eat. Some researchers are looking at ways to genetically interrupt protozoa production that could cause the colony to starve to death.

As food sharing is also known to be an important way that the termites communicate, researchers are looking for ways to use their workday conversations against them, Houseman said.

Termites are unable to hear sound and do not communicate by visual cues as other bugs do. Instead, they secrete varying kinds and amounts of hormones and pheromones into the food that they share with their fellow nestmates. Food offerings are laced with chemical messages that say something important about the health of the colony, the need for more soldiers or to produce more flying termites to find new sources of food.

A chemical or hormone food additive that disrupts communication will eliminate one of the termites' greatest strengths, effectively reducing the colony into millions of confused individuals who can no longer work together.

In addition to considering ways to disrupt communication, researchers are considering another potential attack plan by confusing the termites' ability to navigate. Termites use their sense of smell as their version of a GPS system. They line the tunnels they dig with pheromones, a scent that guides their nestmates to food.

Disrupting the feeding behaviors, genetic systems and the chemical processes termites use to communicate and navigate is a new frontier of termite control. With improved methods of warfare, things may soon get bad for the insects.

But let's not tell the termites, yet. After 300 million years of success, they are bound to be complacent.

Story by: Randy Mertens
Posted: May 18, 2009