Salivary gland substances of the arboreal termite Nasutitermes corniger induce worker aggregation and gnawing of food substrate

Abstract

In social insects, collective behavior is regulated by substances secreted by various glands of different members of society. In this study, we investigate whether salivary glands of the arboreal termite Nasutitermes corniger (Motschulsky) (Isoptera: Termitidae) contain substances that regulate the intensity of foraging behavior. Foraging arenas of N. corniger nests maintained under laboratory conditions received the addition of two filter paper substrates, one impregnated with salivary gland extract from third-instar small workers (SW3) (treatment) and the other impregnated with distilled water (control). A similar experiment was conducted using salivary gland extract from fourth-instar large workers (LW4). Occurrences of initial exploration, mass recruitment, and substrate gnawing behaviors, as well as numbers of recruited and gnawing workers, were recorded. There was a higher rate of mass recruitment to treated substrates than to the control (SW3: 80 vs. 25%; LW4: 90 vs. 25%). Gnawing behavior also occurred at higher rates on treated substrates (SW3: 95 vs. 35%; LW4: 100 vs. 45%). The number of workers recruited to and gnawing on treated substrate was significantly higher than the number of workers recruited to and gnawing on control substrate. The higher rates of worker recruitment, as well as the higher numbers of recruited and gnawing workers, show that salivary glands of last-instar workers contain substances with arresting and/or phagostimulating pheromonal actions or substances that release compounds with these properties.

Termite exocrine systems: a review of current knowledge

“…However, the defensive function of the salivary glands is more often attributed to soldiers, in which these structures are hypertrophied (Maschwitz & Tho, 1974; Howse, 1975; Wood et al, 1975; Šobotník et al, 2010a, b). Additionally, the saliva of the workers has antibacterial properties (Matsuura et al, 2007) and is used for intraspecific communication, as it acts as a food marker and phagostimulant (Kaib & Ziesmann, 1992; Reinhard et al, 2002; Casarin et al, 2003; Gazal et al, 2023). A comparative study of the chemical properties of the salivary secretion in soldiers and workers has confirmed the role of the salivary glands in the defense and digestion in workers, whereas it is restricted to defensive functions in soldiers (Sillam‐Dussès et al, 2012).…”

Introduction to the special section on Biology of Termites

“…There is still a large untapped reservoir of chemical compounds produced by termites, that may not only yield knowledge of the functioning of termites in nature, but that can also be exploited for human wellbeing. Gazal et al (2023) experimentally investigate the role of salivary glands in foraging behaviour of the arboreal termite Nasutitermes corniger (Motschulsky) (Termitidae). They elegantly show that chemical compounds are used by last‐instar workers to either increase or decrease recruitment of gnawing workers as part of the communication between nestmates.…”