Intraspecific Signals Inducing Aggregation in Periplaneta americana (Insecta: Dictyoptera)

Abstract

Chemical communication is necessary to induce aggregation and to maintain the cohesion of aggregates in Periplaneta americana (L.) cockroaches. We aimed to identify the chemical message inducing aggregation in this species. Two types of bioassays were used-binary choice tests in Petri dishes and tests in Y-olfactometer. Papers conditioned by direct contact of conspecifics induce aggregation when proposed in binary choice tests and were attractive in a Y-olfactometer. The identification of the molecules present on these conditioned papers indicated that dichloromethane extracts contained mainly cuticular hydrocarbons whereas methanol extracts contained more volatile molecules. Only a mixture of extracts in both solvents induced aggregation. High concentrations of cuticular hydrocarbons are necessary to induce aggregation when presented alone. When presented with volatile molecules present in methanol extracts, low concentrations of cuticular hydrocarbons are sufficient to induce aggregation if they are presented in contact. Among volatile molecules collected on filter paper, a mixture of three compounds-hexadecanoic acid, pentadecanoic acid, and pentaethylene glycol-induced aggregation. Our results provide evidence that aggregation processes in P. americana relies on a dual mechanism: attraction over long distances by three volatile molecules and maintenance on site by contact with cuticular hydrocarbons.

Two Parallel Olfactory Pathways for Processing General Odors in a Cockroach

“…Among the nine tested odors, the heptanoic acid selectively activated type1 PNs ( Figure 3B ). In the cockroach, behavioral repercussions of the heptanoic acid remain unclear, but some types of fatty acids, such as butyric acid, hexadecanoic acid, and pentadecanoic acid, exhibit attractive effects (Imen et al, 2015). In addition, type1 PNs with dendrites in T10 glomeruli exhibited excitatory responses to temperature and humidity changes (Nishino et al, 2003).…”

Sensory neurons that respond to sex and aggregation pheromones in the nymphal cockroach

“…2B-D). Thereafter, we increased the number of test odourants included six reported attractants of nymphal cockroaches 5,[35][36][37] and eight chemically diverse odourants that are frequently used for classification of OSN types (Table 1) 20,22,38 . Each of the general odours largely activated the sw-A1, sw-A2 and grooved basiconic sensilla ( Fig.…”

“…As cockroaches are one of the major pests in urban environments, effective control of their behaviour using pheromones has been extensively investigated with regarding to ecological, pharmacological and physiological aspects. Thus, pheromones have been identified in several species of cockroaches [2][3][4][5] . In the American cockroach, Periplaneta americana, two sex pheromones have been isolated, the subcomponent periplanone-A (PA) and the main component periplanone-B (PB) [6][7][8] .…”

The neural basis for insect pheromonal communication

“…Aggregation pheromones that act over long-distances are typically volatile and sensed by the olfactory system [11]. In contrast, the cockroach, Periplaneta americana , which aggregates during its diurnal resting phase, uses both high- and low-volatile CHCs for the attraction to an aggregation site and the subsequent maintenance of aggregation behavior, respectively [12]. Additionally, pheromone-driven social behaviors that are independent of mating are common in social insects, which include nestmate recognition, and nest defense, in which volatile alarm pheromones recruit conspecifics to attack intruders [2,13].…”