Exploration of substrate vibrations as communication signals in a webspinner from Ecuador (Embioptera: Clothodidae).

Embiopterans are among the least known of all insect orders, and yet their behavior is worthy of investigation for many reasons. They spin silk produced in glands in their front tarsi and live in groups, usually mothers with their young and sometimes in large colonies with many reproductive females sharing the silk. We discovered a large embiid (Clothodidae) in an Ecuadorian rain forest living under camouflaged silk sheets spun onto the bark of trees. Observations in previous studies of a related Trinidadian clothodid revealed that individuals shake and lunge their bodies in response to intruders of their silk domicile. We took the opportunity afforded by the discovery of the large clothodids to rear them in the laboratory and to investigate their communication behavior. We used piezoelectric film to detect substrate vibrations generated by adult females as elicited by a variety of intruders (an artificial stimulus, conspecific female or male, or a female of different species of webspinners). The residents produced three signals distinguishable by behavioral action, frequency (hertz), pulses per bout, and amplitude at peak frequency. We designated these as lift silk, shake, and snapback. Shakes varied the most in amplitude and frequency in response to the different intruders, and therefore, we propose that shakes may transmit the most information as individuals contact each other. This is the first report to characterize spectral qualities and contexts of substrate vibrations in an embiopteran.

Intraguild predation among larval treehole mosquitoes, Aedes albopictus, Ae. aegypti, and Ae. triseriatus (Diptera: Culicidae), in laboratory microcosms.

We compared the tendency for 4th-instar larvae to prey on newly hatched larvae, and the vulnerability of those 1st instars to such predation for Aedes triseriatus (Say), Ae. aegypti (L.), and Ae. albopictus (Skuse), all container-breeding mosquitoes. The latter 2 species were introduced to North America and are now sympatric with Ae. triseriatus, a native species in eastern North America. The experiment also enabled the assessment of species-specific influences of food supplements and spatial heterogeneity on predatory behavior. Ae. triseriatus was substantially more predatory and less susceptible to attack than the other 2 species. These differences were amplified in food-deprived and spatially simple conditions, indicating that Ae. triseriatus predatory behavior may have important retarding effects on the colonization of occupied treehole habitats by Ae. albopictus. Ae. aegypti and Ae. albopictus were similar in imposing little (Ae. aegypti) or almost no (Ae. albopictus) predation on 1st instars and in being susceptible to predation by Ae. triseriatus. The general lack of species-specific differences between Ae. aegypti and Ae. albopictus indicates that interspecific predation is not a likely explanation for the rapid displacement of Ae. aegypti by Ae. albopictus in domestic containers in the southeastern United States.

Site of secretion of the trail marker of the eastern tent caterpillar.

A new site of secretion of a chemical trail marker was found on the sternum at the tip of the last abdominal segment of the larva of the eastern tent caterpillarMalacosoma americanum. Larvae marked from this site by drawing their sterna along the substrate when they extended existing trails in search of food and again when they established recruitment trails to food-finds. Differences in the quantity or quality of the marker deposited by exploring and recruiting caterpillars may account for the greater activity of the recruitment trails.