Antennal sensilla essential for off-host aggregation behavior by bed bugs, Cimex lectularius

Previous research indicated that off-host aggregation by bed bugs is mediated by sensory structures located on the proximal segments of the antennae. In addition, filter paper disks stained by engorged adults causes arrestment in multi-choice arena assays. We performed similar assays to identify the specific antennal segments, or portions thereof, essential for aggregation. In our first experiment, we conducted ablations to individual segments on groups of bugs prior to release into experimental arenas with stained papers. Results indicated that removal of the pedicel segment significantly reduced arrestment under stained disks. Scanning electron microscopy of the pedicel showed five distinct types of sensory structures, four of which were clustered together in a patch-like distribution, which was located on the distal portion of the segment. No sexual dimorphism was found in the structure, frequency or distribution of the antennal sensilla. Serrated hairs were distributed evenly and covered most of the segment. A second multi-choice behavioral assay was conducted to determine the importance of the sensilla patch. Anntenectomies were performed midsection of the pedicel prior to release into the arena. Results indicated that removal of the patch did not affect aggregation among groups of bed bugs. These findings suggest serrated hairs are essential to aggregation by bed bugs. Investigations via transmission electron microscopy and electrophysiological recordings of the serrated hairs will provide additional insight to the importance of these structures.