Necessary Pestilence continued...

In the Sonoran Desert large, well-established termite colonies of many species produce nymphs in the late spring. When these nymphs shed their external skeletons for the last time, fully-formed functional wings unfold from the wing pads, and the resultant individuals are called alates. Alates are reproductively mature males and females ready and eager to start their own new colonies. They stay in the parent colony until conditions are optimal (usually during or after a rain); then they leave the galleries of the colony, surrounded by soldier termites ready to defend their brothers and sisters against ants and other enemies as they depart. The alates then take flight.

The season and time of termite flights depend on the species, but alates from all colonies of a given species in an area fly simultaneously. Just how far alates actually fly is not known for any species, but it is assumed that the flights of the reproductive-ready serves to assure new colonization some distance from the home colony – which minimizes competition for existing food and water. The simultaneous flights also promote outbreeding by increasing the probability that reproducers from one colony will mate with members of other colonies.

Soon after winged termites alight, they shed their wings by breaking them off at lines of weakness (like perforations in paper) near the point of their attachment to the body. Females may then use a chemical odor called a pheromone to “call” males. Males attracted to this potent chemical concoction may be accepted or rejected by the female. A rejected male is forced to try his luck elsewhere. The fortunate male who is accepted by a female is permitted to follow her on the ground as she runs quickly about looking for the ideal place to start a new colony. During this “tandem running” phase of courtship, the male remains within touching distance of the female until she finds the “perfect” place (in the ground or in dead wood, again depending on the species of termite and the habitat) to begin a new colony. The pair then settles into a monogamous relationship, and cooperative family rearing.

After mating, the queen lays a few eggs that soon hatch into tiny termite larvae. These are fed and nurtured by both the mother and father until they are large enough to begin foraging for wood and other sources of cellulose, at which time the young termites take over the work of feeding the larvae that have hatched from a second set of eggs. When the parents feed their first batch of offspring, the protozoans (microscopic animals made up of a single cell or a group of more or less identical cells and living in water or as parasites, including ciliates, flagellates, rhizopods, and sporozoans) required to produce the enzyme needed for cellulose digestion are transferred from the mother’s and father’s stomachs to the larvae. This protozoan inoculum is all that is required to get a culture going in the offspring so that they too, with the aid of the microbes, can digest their own cellulose.

Termites can accurately be described as “tiny social cockroaches” because they evolved from a common ancestor with wood-dwelling cockroaches, to whom they are very closely related. They first appeared on earth during the age of the dinosaurs, about 100 million years ago. Termites are social in ways not unfamiliar to humans. We live together with others of our kind in complex societies, we divide the many tasks needed to support our communities and we care for our young long after they are born. Termites likewise live in complex societies, have division of labor, and care for their young.

A well-established termite society or colony minimally consists of a king and queen, which are responsible for producing offspring: soldiers, which defend the colony against its enemies; and workers, which collect and process wood or other sources of cellulose and feed the royal couple and the soldiers, which are unable to feed themselves. Workers also care for eggs produced by the queen, and they tend to the young termite larvae that hatch from these eggs. The categories of king, queen, soldiers, and workers in a termite colony are referred to as castes. All of these are wingless; however, after a termite colony reaches a certain size (a few dozen to several thousand individuals, depending on the species), the colony begins to produce nymphs. These nymphs have small pads on their backs that contain developing wings. Regulation of the development of different castes in a termite colony is controlled by chemicals in the colony that are transferred from individual to individual by social feeding called tropholaxis. Exactly how different developmental trajectories are regulated in termite colonies remains an entomological mystery.

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