View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Animal Behaviour 81 (2011) 463e467 Contents lists available at ScienceDirect Animal Behaviour journal homepage: www.elsevier.com/locate/anbehav Nestmate recognition in the stingless bee Frieseomelitta varia (Hymenoptera, Apidae, Meliponini): sources of chemical signals Túlio M. Nunes a,*, Sidnei Mateus a, Izabel C. Turatti b, E. David Morgan c, Ronaldo Zucchi a a Departamento de Biologia, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo b Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo c Chemical Ecology Group, Lennard-Jones Laboratory, Keele University article info Social insects use cuticular lipids for nestmate recognition. These lipids are chiefly hydrocarbons that can Article history: be endogenously produced or acquired from the environment. Although these compounds are already Received 14 April 2010 described as coming from different sources for different groups of social insects, nothing is known about Initial acceptance 31 May 2010 the source of cuticular hydrocarbons in stingless bees. We used behavioural recognition tests and cuticle Final acceptance 15 November 2010 chemical investigation to elucidate the role of endogenous and environmentally based cues for nestmate Available online 24 December 2010 recognition in the stingless bee Frieseomelitta varia. We found that although newly emerged workers MS. number: A10-00258R present specific cuticle patterns according to their nest origin, these compounds are not used for nest- mate recognition, since newly emerged workers are broadly accepted in different colonies. The cerumen Keywords: used in nest construction played an important role in recognition behaviour. Twenty minutes of contact cerumen with foreign cerumen was sufficient to increase the rejection rates of nestmates and separate the groups cuticle compound of workers according to their chemical profile. On the other hand, tests of feeding on a common diet diet hydrocarbon showed no effect on chemical cuticle pattern or recognition behaviour. Ó newly emerged worker 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. Open access under the Elsevier OA license. Communication between individuals is an essential element of responsible for producing the cues in the cue-bearer would be social organization. That communication can be through any or all of responsible for producing a recognition ability of such cue in the the senses. Chemical communication by odour is most highly evaluator (D’Ettorre & Lenoir 2010). Similarities between label and evolved in social insects, and is probably their most important route template result in acceptance behaviour, while differences in these of communication. One of the requirements of social organization is factors result in rejection, although acceptance and rejection errors the recognition of nestmates and distinguishing them from non- may occasionally occur (Sherman et al. 1997). nestmates. Stingless bees, like other social insects, are able to Recently, the cuticular labels of stingless bee species have been distinguish between nestmates and non-nestmates (Nunes et al. the focus of several investigations. The cuticle of stingless bees, as in 2008) by chemical cues present on their cuticle. Each individual in other social insects, is a rich source of information that is important a colony presents a blend of compounds on its cuticle that may also for the regulation of their society (Pianaro et al. 2007, 2009; Nunes carry information regarding its sex, age, caste, group task as well as et al. 2008, 2009a, b). Nunes et al. (2009b) described qualitative colony (Howard & Blomquist 2005). In recognition procedures, one and quantitative differences in the chemical composition of cuticular individual (evaluator) compares the chemical label of a newly pre- lipids between males and workers of the stingless bee Frieseomelitta sented individual (cue-bearer) with some kind of internal template. varia. Similar differences were described for young and old indi- The evaluator can learn which cues to recognize by prior associations viduals of both sexes. Yet, fertile laying queens of this species pre- with frequently encountered individuals. The template can also sented a completely different composition in their cuticle compared come from phenotype matching, in which the evaluator uses the to workers (Nunes et al. 2009b). The composition of cuticular cues learned from other individuals. An additional option is hydrocarbons showed a strong correlation with behaviour in this the recognition behaviour ruled by genetic basis. In this system, the species, suggesting a direct relationship between cuticular labels and phenotypic cues are the result of genetic expression. The same genes discriminatory behaviour. For F. varia, non-nestmates with similar cuticle labels to a foreign colony are more likely to be accepted into that foreign colony than individuals with divergent cuticular hydrocarbon composition (Nunes et al. 2008). * Correspondence: T. M. Nunes, Faculdade de Filosofia Ciências e Letras de Individuals of the sweat bee Lasioglossum zephyrum are able to Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900, Ribeirão Preto (SP) 14040-901, Brazil. discriminate between more or less genetically related individuals, E-mail address: [email protected] (T.M. Nunes). with rising acceptance rates as the genetic relationship rises 0003-3472 Ó 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. Open access under the Elsevier OA license. doi:10.1016/j.anbehav.2010.11.020 464 T.M. Nunes et al. / Animal Behaviour 81 (2011) 463e467 (Greenberg 1979). Other studies have suggested that environ- resident bees. The introduction tube was opened to the interior of mentally acquired cues can also be important in recognition the experimental box and sealed at the other exit by a removable behaviour. According to Downs & Ratnieks (1999), environmentally cork. acquired cues can even exceed the effect of endogenously produced Individuals used for the tests were placed singly in small glass ones, and be fundamental in nestmate recognition. Exogenously vials (3.5 cm height  2.0 cm diameter). To decrease the agitation of acquired recognition cues may come from many different sources. the collected bee, the glass vials were kept in ice for about 2 min. The The Argentine ant Linepithema humile can incorporate into its bee was then removed from the vial and introduced into the exper- cuticle single compounds from its diet, which are used for nestmate imental box through the introduction tube. Interactions between the discrimination (Liang & Silverman 2000). Materials used in nest introduced individual and the residents were recorded for 5 min after construction may also provide recognition cues for bees and wasps. the introduction. Aggressive displays, such as biting of wings or legs, In honeybees, wax is probably the most important contribution to immobilization, and resin deposition were considered as rejection, cuticle label. Breed et al. (1995) found that 5 min of contact with while absence of aggressive behaviour and entrance of the individual wax from a different nest resulted in a significant rise in rejection into the main colony box was considered acceptance. Only one rates of contaminated individuals by nestmates. Exchange of comb individual was introduced per test, a 15 min interval was allowed wax between two colonies significantly raised acceptation rates of between introductions, and each collected individual was tested only workers between nests. Moreover, chemical analyses revealed that once. after comb wax was exchanged between colonies, the cuticular The experiments followed the guidelines for animal care licensed lipid composition of individuals from each colony became more by the Brazilian environment and renewable natural resources similar. The acceptance rates of foreign workers, however, declined institute (IBAMA license number: 15200-1). after a few weeks, showing that the cuticle substances were being constantly renewed (D’Ettorre et al. 2006). It was concluded from Acceptance and Rejection of Newly Emerged Individuals these studies of honeybees that different sources of colony odour can be absorbed and redistributed through the wax, resulting in Four colonies of F. varia, taken in pairs, were used for this test. a single homogenous odour for the whole nest (Breed et al. 1995; The first colony of each pair provided newly emerged and old D’Ettorre et al. 2006). individuals to be tested, according to the behavioural recognition A remarkable finding is that newly emerged honeybee workers test described above. We tested recognition and acceptance of each are not rejected from any colony into which they are inserted. Breed individual in its own colony and also in the second colony of the et al. (2004) observed that these individuals have low quantities of pair. We tested 30 individuals (15 newly emerged, 15 old workers) lipid substances associated with their cuticle. The authors sug- in each pair of colonies. gested that the absence of recognition cues is responsible for these high acceptation rates, and that individuals acquire recognition Acceptance and Rejection of Nestmates in Contact with cues as they get older (Breed et al. 2004). Foreign Nest Material In this report, we investigated different possible