Behavioural Repertoire of Termites in Corpse Management A
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Behavioural Processes 157 (2018) 431–437 Contents lists available at ScienceDirect Behavioural Processes journal homepage: www.elsevier.com/locate/behavproc Behavioural repertoire of termites in corpse management: A comparison between one-piece and multiple-pieces nesting termite species T ⁎ Luiza Helena Bueno da Silva, Ana Maria Costa-Leonardo Laboratório de Cupins, Departamento de Biologia, Instituto de Biociências, UNESP – Univ Estadual Paulista, Av. 24A, 1515, CEP: 13506-900 Rio Claro, SP, Brazil ARTICLE INFO ABSTRACT Keywords: Corpse disposal is an essential adaptation to social life. This behaviour promotes nest hygiene and prevents the Cannibalism spread of pathogens in the colony of social insects. The current study verified the corpse management in two Cornitermes cumulans termite families towards cadavers of different origins. We carried out bioassays with subcolonies of Cryptotermes Corpse-burying behaviour brevis and colonies of Cornitermes cumulans, in which corpses of termite workers from the same colony, from Cryptotermes brevis another colony and from another species were introduced. The results showed that C. brevis consumed the Isoptera corpses regardless of their origin, but they avoided the chitinous parts of the head. In this species, consumption Undertaking behaviour of dead individuals, besides performing a hygienic function, seems to be a strategy for nitrogen and water acquisition. In the C. cumulans species, interspecific and intercolonial corpses were covered with soil and faeces after being groomed. Nestmate corpses were entombed, transported to the nest or ignored after being submitted to grooming. Our findings indicate that a one-piece nesting termite, as C. brevis, exhibited a simplified corpse management repertoire in relation to that performed by C. cumulans, a multiple-piece nesting species, whose approach was more complex and diverse. Behavioural responses are associated with the nesting of the species. 1. Introduction or chemical (Sun and Zhou, 2013). Two main hypotheses about the recognition through chemical signals are accepted. One of them is that The presence of dead individuals inside social insect nests can death recognition occurs due to the accumulation of postmortem sub- present a risk of contamination with pathogens, damaging the integrity stances. In several insects, the accumulation of unsaturated acids, e.g. of the colony (Cremer et al., 2007). Corpse management is considered oleic acid and linoleic acid, elicits undertaking responses. According to to be an important characteristic of adaptation to social living and, to Wilson (1985), two species of ant, Pogonomyrmex badius and Solenopsis prevent prolonged contact with corpses, the social insects perform saevissima, recognise dead individuals due to the emission of fatty acids, different undertaking strategies (López-Riquelme and Fanjul-Moles, especially oleic acid. Studies with other species of ant, as well as bee 2013). These strategies consist of a complex and sophisticated sequence and termite, corroborate the hypothesis of "fatty acid as warning of of behavioural patterns elicited by the presence of cadavers of different death" (Haskins and Haskins, 1974; Howard and Tschinkel, 1976; origins, ages and infection status (Sun and Zhou, 2013). The beha- Ulyshen and Shelton, 2012; Visscher, 1983; Yao et al., 2009). The vioural responses for disposing of corpses vary among the social insect second hypothesis is that corpse management is triggered by a reduc- groups and are dependent on the feeding habit and nest ecology (Neoh tion of vital chemical signs present in the cadaver cuticle, such as the et al., 2012). Honey bees remove nestmate corpses from their nest, disappearance of dolichodial and iridomyrmecin on the corpse cuticle while ants remove cadavers to the exterior of the nest or to special of the ant Linepithema humile (Choe et al., 2009). chambers (Visscher, 1983; Wilson et al., 1958). In some ant species, One of the termite species studied is Cryptotermes brevis (Walker, however, both burial and cannibalism have also been documented 1853), whose origin is probably Peru-Chile (Scheffrahn et al., 2009), (Driessen et al., 1984; Renucci et al., 2011). Likewise, termites perform that is a drywood termite belonging to the Kalotermitidae family. This varied responses that include avoiding contact with the corpse, canni- species is a one-piece nesting termite, i.e., it nests in the piece of wood balism, removal and burial (Sun and Zhou, 2013). that serves as food resource (Korb, 2005). The colonies of C. brevis live Social insect colony members must be able to distinguish between in woods with humidity below 30% and, therefore, these termites ob- dead and living individuals before initiating corpse management. Death tain humidity from their own food and conserve it through the pro- recognition depends on varied cadaver cues, which can be tactile and, duction of dry faeces (Brazolini et al., 2001) ⁎ Corresponding author. E-mail addresses: [email protected] (L.H.B. da Silva), [email protected] (A.M. Costa-Leonardo). https://doi.org/10.1016/j.beproc.2018.07.005 Received 23 February 2018; Received in revised form 8 July 2018; Accepted 15 July 2018 Available online 30 July 2018 0376-6357/ © 2018 Elsevier B.V. All rights reserved. L.H.B. da Silva, A.M. Costa-Leonardo Behavioural Processes 157 (2018) 431–437 The other studied termite is Cornitermes cumulans (Kollar, 1832), 2.4. Bioassays that is a Netropical termite belonging to the Termitidae family, which occurs in Brazil, Paraguay and Argentina (Araújo, 1970). This species is To compare the behavioural responses of C. brevis and C. cumulans a multiple-piece nesting termite, whose colonies live in a well-define towards corpses from different origins, three bioassays were performed, nest separated from the food source (Korb, 2005). It builds mound nests each bioassay based on a different corpse origin as follows: a) in- that may reach considerable size and presents large population when tracolonial corpse: cadaver from the same colony; b) intercolonial compared with those of C. brevis. corpse: cadaver from the same species collected in other colony; and c) Corpse management have been studied in termites, but there is no interspecific corpse: dead worker of Coptotermes gestroi. We used record about this subject in the basal Kalotermitidae family. In the corpses of cospecific pseudergates and workers in experiments with C. Termitidae family, there are reports of corpse management in brevis and C. cumulans, respectively. In each test, the lid or glass sheet Pseudacanthotermes spiniger dealated female that buried corpses of other was gently removed and one corpse was introduced in the experimental females for the purpose of nest hygiene (Chouvenc et al., 2012). La- arena, which was then covered to avoid disturbance by airflow. All boratory studies of the competition between two Neotropical termitids, bioassays were replicated 10 times. The video recording was performed C. cumulans and Procornitermes araujoi, showed that, after confronta- using a videocamera (Sony HDR-CX130 full HD) and started im- tion, individuals killed during it were used to block tunnels and to deter mediately after the corpse introduction. Empirical studies were carried other species (Jost et al., 2012). out to determine a 15-minute recording time for bioassays with C. brevis In the present study, we evaluated the corpse management in C. and 20-minutes for C. cumulans. The bioassays were conducted under brevis and C. cumulans under laboratory conditions to verify the beha- red light (methodology of Machida et al., 2001) at 25 ± 2 °C with > vioural repertoire and the consequent final disposal of termite corpses. 80% RH. We tested cadavers of different origins, which might replicate natural We carried out qualitative observations to define the main cate- contexts (for example, confrontation interactions between termites that gories and behavioural acts exhibited by C. brevis towards and near the could result in the death of a nestmate or alien). We hypothesized that corpses, which compose the behavioural repertoire of corpse manage- termites would perform different corpse management according to the ment. The frequency of the following behaviours of C. brevis individuals origin of the cadaver and the nesting ecology of the species. was recorded: antennation, retreat (avoid confrontation), agonism, alarm (oscillatory movement with the whole body), grooming and ffi ff 2. Material and methods corpse ingestion. Due to di culty in di erentiating grooming from ingestion, both behaviours were analysed together and their duration 2.1. Termites was evaluated. Final observations were made 72 h after the beginning of the experiment and, to quantify the consumption, a point was given Ten natural colonies of C. brevis were extracted from several pieces to each body part that was consumed. Thus, each of the following parts, of infested furniture collected in different districts of the city of Rio if ingested, received a point: antenna (two in total), legs (six in total), Claro, SP, Brazil (22° 24′S, 47° 33′ W). Two nests of C. cumulans were abdomen, thorax and damaged head; the maximum total was 11 points collected in Rio Claro, SP, Brazil (22° 23′S, 47° 32′ W), transported to per cadaver. The three behavioural bioassays were performed once in the laboratory and maintained at 25 ± 2 °C, > 80% relative humidity each of the ten C. brevis subcolonies. Tests in the same subcolony were (RH) in complete darkness. Each nest was provided with water and food separated by at least one week. ad libitum. Experimental tests with C. cumulans started when one corpse was placed into the region located between the opening of the connector tube and the food in the observation arena, that is, in the trail of the 2.2. Preparation of corpses termites to the food. Each bioassay was replicated five times in both nests of C. cumulans. Qualitative observations were used to determine ff Undertaking responses to corpses of di erent origins were tested in the main categories of behaviour exhibited by C. cumulans individuals subcolonies of C. brevis and colonies of C.