Hernández J.V1, D. Rodríguez1, Z. Tárano2, Falko P. Drijfhout3, and E.D Morgan3. (1) Biología de Organismos, Universidad Simón Bolívar, Sartenejas- Baruta, Caracas, 1080A, Venezuela, (2) Facultad de Ciencias, Inst. Biología Experimental, Universidad Central de Venezuela, Bello Monte, Caracas, Venezuela, (3) Chemistry, Keele University, Lennard Jones Lab, Keele, United Kingdom
In ants, the sources for intraspecific and interspecific recognition have been controversial subjects. To gain insight about the source for recognition in ants we use as model the ant C.(abdominalis) atriceps. Behavioural bioassays were undertaken by placing two worker ants in a neutral arena (Petri dish 5 cm Ø). Ants were collected from eight nests at cacao research field station Padrón at INIA-Miranda, Miranda State, and transported to Laboratorio de Comportamiento, Universidad Simón Bolívar, Caracas, Venezuela. Three types of bioassays were carried out: a) whole bodies isolated for 0 h, 12 h and 24 h individually, b) headless ants and c) 48 h lyophilised ants impregnated with glandular extracts (post-pharyngeal (PPG) and mandibular gland (MG) extracts). For the three types of bioassay, six different treatments were used. Treatments were performed with pairs of nestmate (NM) and non-nestmate (NNM) ants. Chemical analysis of the MG and PPG secretions of individuals from two different colonies were undertaken with GC and GC/MS. by using headspace analysis (solid phase micro-extraction (SPME)) and solid sample injection technique. Agonistic interactions were significant higher in NNM compared with NM bioassays (Mann Whitney U Test, N=12, Z= 0,38, P0=0.05). Isolation bioassays do not modified the agonistic behavior. However, workers were unable to discriminate NM and NNM in the treatment using headless workers as no significantly differences were observed (Mann Whitney U Test, N=12, Z=1.10, P=0.27). Both MG and PPG show differences within different castes and between nests in the relative proportions of these secretions as statistically significant differences were observed (ANOVA Test). Both worker castes show MG secretion dominated by 4-methyl-3-heptanone, methyl 2-hydroxy-6-methylbenzoate and 4-methyl-3-heptanol. PPG secretions show an amazing number of straight-chain and methyl-branched hydrocarbons. Behavioural and chemical evidence support the hypothesis that MG secretion is likely to be the source for nestmate recognition in this ant.
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