Pterotermes occidentis
FAMILY
Kalotermitidae
TAXONOMY
Termes occidentis Walker, 1853, Baja California, Mexico.
OTHER COMMON NAMES
None known.
PHYSICAL CHARACTERISTICS
Large, alates 0.7–0.78 in (18–20 mm) from head to wing tips; antennae with 20 or 21 segments, reddish brown. Soldiers heavy bodied, 0.5–0.6 in (14–15 mm); toothed mandibles, round heads with black compound eyes, broad pronotum, thorax with wing pads, brilliant orange and yellow. Pseudergates large with large compound eyes.
DISTRIBUTION
Sonoran Desert, including Baja California and Sonora, Mexico, and southwestern Arizona, United States.
HABITAT
Dead standing branches of paloverde trees of the genus Cercidium.
BEHAVIOR
Colonies pro-eusocial, rarely exceed 3,000 individuals; most mature colonies have standing population of 1,000 to 1,500. All individuals develop as nymphs. About 5% of nymphs have wing pad scars resulting in development as pseuder-gates, comprising about 10 to 15% of population. Pseuder-gates may molt to presoldiers and then to soldiers. Soldiers comprise about 2% of population, guard breaches of the galleries. Nymphs molt to alates in July, small numbers fly from nest at night over flight season from late July through September. Dispersal flights last at least four minutes but not more than one hour. Alates seek beetle emergence holes on dead paloverde trees, which male and female pairs enter and seal off copularium. Primary reproductives always bite off the distal halves of their antenna for reasons that remain unknown.
FEEDING ECOLOGY AND DIET
Xylophagous; colonies excavate wide, meandering galleries inside dead paloverde branches. Occasionally found in saguaro cactus skeletons.
REPRODUCTIVE BIOLOGY
Most colonies headed by pair of primary reproductives. However, if one or both are removed, pseudergates start to molt within weeks to become replacement reproductives. When excess numbers molt following death of primaries, lethal fighting follows among neotenic replacements until one male and one female reproductive again become established and suppress, presumably by inhibitory pheromones, further neotenic molting.
CONSERVATION STATUS
Not threatened. Critical habitat (dead standing branches of paloverde trees) not utilized by humans except sometimes as firewood. However, as the species is monophagous on one tree species and standing branches on tree are limited, could be subject to local extirpation if intensively collected near urban areas.
SIGNIFICANCE TO HUMANS
Excellent study organism because of large size and ease of maintenance; one of the most well-studied North American drywood termites. Not a pest; no known economic value.
