Termites are soil or wood inhabiting eusocial insects which generally have soft, white bodies and secretive habits. Most termites each dead plant material, which is digested with the help of bacterial or protozoan symbionts in their gut. Globally, termites play an important role in reducing dead plant material, but they can be quite destructive to human-built structures.
In many species of termite the nest is simply the cavities created in the wood as the termites eat, but in African and Australian grasslands some termites construct large nests of soil which is cemented with feces and saliva. In tropical rainforests Nasutitermes species attach their nests of chewed plant material and feces to trees, fence posts, and other aboveground locations. Nasutitmermes workers construct covered walkways from their nest to foraging areas.
At the appropriate season for establishing new colonies, winged females and males (alates) leave their nest and join in a mass mating flight which is composed of many (thousands or even millions) of alates from that species' colonies. Males and females form pair bonds, and you may see pairs of males and females running, with the male closely following the female (this is called tandem running) in search of nesting location. Once the male and female have paired, they break off their wings, and spend the remainder of their life flightless.
These mass mating flights are easy pickings for predators--frogs, lizards,
birds, and spiders all may benefit greatly from the easy availability of termite
alates as food. This may be an example of predator
saturation; the termite colonies produce far more alates than could possibly
find nesting sites in order to insure that at least a few survive. Unlike ants,
bees and wasps, termite workers may be male or female. The king continues to
live after his initial mating with the queen and lives in the nest; the king
and queen may remate occasionally.
Termites have incomplete metamorphosis. This means that, like cockroaches and grasshoppers, immatures look very much like adults, lacking only wings. Termite workers are essentially immatures, and in the "lower" termites, workers may ultimately develop into reproductives.
At hatching termite immatures lack the intestinal symbionts which enable them to digest cellulose. They gain their initial infection of symbionts by feeding on feces from other termites in the colony. Usually such feeding is directly from the anus of the other individual--this is called proctodael feeding.
In order to grow, insects must shed their exoskeleton by molting. When a termite molts it also loses the linings of its foregut and hindgut, as well as the symbionts living in the gut. Termites rely on proctodael feeding in order to reinfect themselves with their symbionts after they molt; the symbionts are regained from the feces of another termite.
Studies of caste in termites are based on measurements of workers. The measurements allow the scientist to determine to which molt the worker belongs. Both males and females serve as workers, and in some species there are sex differences among the workers in their role in the colony. In general, termite workers can be divided into nest workers, who construct the nest and care for the eggs, foragers, who are equipped for chewing wood or other plant material, and soldiers, whose large heads, strong jaw muscles, and sharp jaws enable them to defend the colony from attackers such as ants. Nest worker and foragers have smaller heads. Head size, gender, and behavioral role can be combined in a diagram of termite caste:
**insert caste diagram**
Termites often work in the dark, and their best-known modes of communication are pheromones. Trail pheromones guide foragers to food. Other pheromones may regulate how many members of each caste are produced, or may inhibit workers from becoming reproductives.
Some species also produce vibrational signals by striking a surface with their heads. Thousands of termites simultaneously bashing their heads produces a noise that is audible to humans at a distance of several meters. Head bashing communicates alarm, alerting the entire nest to a threat. Termites probably lack a hearing organ--they perceive the signals as vibrations through their legs or antennae.
copyright ©2002 Michael D. Breed, all rights reserved