Zootermopsis

Zootermopsis is one of the best studied termite genera, as it is easy to collect and culture, and is found close to where a large number of biologists are based.

Species of the genus are found in wet woodlands, and colonies have been found in a number of broad-leaved and coniferous trees (e.g. Populus spp. , Alnus spp., Salix spp.)

Colonies are founded in unhealthy trees or those with dead branches. Zootermopsis appears to be able to feed on living tree, but probably only if attacked by fungi (e.g. Nutting, 1965, reports a colony found in the fungus-infested wood of a willow. The relationship between Zootermopsis and fungi may be obligate, and the termite may feed at least partially on the fungal tissue (Weesner, 1965).

Colonies appear to be able to survive very high and very low temperatures. They appear to undergo a form of diapause under snowy or frosty conditions (Weesner, 1965).

Colonies are usually established immediately under the attached bark of sound, dead conifers. Mature colonies are usually found in rotten wood, so presumably established colonies age with the wood. Many new colonies can be found under the bark of a single log (Weesner, 1965). Shelman Reeve (1994) showed that mated founding pairs co-operate to maximise their consumption of cambium-nitrogen, and this has an important influence on initial colony growth. Pairs also co-operate to repulse intruder reproductives (Shelman Reeve, 1997). Two parent colonies are significantly more likely to thrive than one-parent ones (Shelman Reeve, 1997).

As with other termopsids colonies consist of kings, queens, larvae, pseudergate nymphs and soldiers. Reproductives are usually fully winged, but neotenic reproductives have been recorded (Greenberg & Stuart, 1982). True workers are not present, and third to seventh instar pseudergates act as a single functional caste performing all the colony work, with no age-related division of labour (Rosengaus & Traniello, 1993a). In laboratory cultures, pseudergates of Z. nevadensis cover nests and feeding materials with large amounts of faecal carton material. Under natural conditions this behaviour may be related to plugging holes the presence of which may be detected by shifts in air currents (Howse, 1965).

Head banging warning behaviour, found in many wood-inhabiting genera, has been well studied in Zootermopsis (Howse, 1964; Kirchner et al., 1994).

The number of reproductives in colonies of Z.nevadensis appears to be positively correlated with group size, and negatively correlated with the number of reproductives already present (Hahn, 1993a). Control of this process may be by a form of nutritional castration delaying sexual maturation as a function of the ratio of nutrient-gathering and nutrient-receiving castes. This mechanism seems to work entirely through reproductives inhibiting the reproductive maturation of pseudergates of the same sex (Hahn, 1993b).

Outbreeding may be the norm in the genus (although Rosengraus & Traniello, 1993b, showed that outbreeding was associated with higher levels of disease than inbreeding in Z. angusticollis ). Females may disperse further (or spend longer searching for nest sites) than males, perhaps to reduce the probability of inbreeding (Shelman Reeve, 1996). Broughton (1995, using mtDNA haplotype techniques) showed that colonies may sometimes consist of queens with different parentages.

Swarming appears to occur all year round, with peak flights in late summer and early fall. Z. laticeps appears to fly at night (Nutting, 1965), while Z. angusticollis and Z. nevdensis fly at dusk just before sunset.