title: How to escape from the host nest: imperfect chemical mimicry in eucharitid parasitoids and exploitation of the ants' hygienic behavior.
abstract: Communication in ants is based to a great extent on chemical compounds. Recognition of intruders is primarily based on cuticular hydrocarbon (CHC) profile matching but is prone to being cheated. Eucharitid wasps are specific parasitoids of the brood of ants; the immature stages are either well integrated within the colony or are protected within the host cocoons, whereas adult wasps at emergence must leave their host nest to reproduce and need to circumvent the ant recognition system to escape unscathed. The behavioral interactions between eucharitid wasps and workers of their host, the Neotropical ant Ectatomma tuberculatum, are characterized. In experimental bioassays, newly emerged parasitoids were not violently aggressed. They remained still and were grabbed by ants upon contact and transported outside the nest; host workers were even observed struggling to reject them. Parasitoids were removed from the nest within five minutes, and most were unharmed, although two wasps (out of 30) were killed during the interaction with the ants. We analyzed the CHCs of the ant and its two parasitoids, Dilocantha lachaudii and Isomerala coronata, and found that although wasps shared all of their compounds with the ants, each wasp species had typical blends and hydrocarbon abundance was also species specific. Furthermore, the wasps had relatively few CHCs compared to E. tuberculatum (22-44% of the host components), and these were present in low amounts. Wasps, only partially mimicking the host CHC profile, were immediately recognized as alien and actively removed from the nest by the ants. Hexane-washed wasps were also transported to the refuse piles, but only after being thoroughly inspected and after most of the workers had initially ignored them. Being recognized as intruder may be to the parasitoids' advantage, allowing them to quickly leave the natal nest, and therefore enhancing the fitness of these very short lived parasitoids. We suggest that eucharitids take advantage of the hygienic behavior of ants to quickly escape from their host nests.
authors.affiliation: El Colegio de la Frontera Sur, Av. Centenario km 5.5, Chetumal 77014, Quintana Roo, Mexico. Electronic address: igperez@ecosur.mx.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Pérez-Lachaud
authors.affiliation: El Colegio de la Frontera Sur, Carr. Antiguo Aeropuerto km 2.5, Tapachula 30700, Chiapas, Mexico.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Bartolo-Reyes
authors.affiliation: El Colegio de la Frontera Sur, Carr. Antiguo Aeropuerto km 2.5, Tapachula 30700, Chiapas, Mexico.
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Quiroa-Montalván
authors.affiliation: El Colegio de la Frontera Sur, Carr. Antiguo Aeropuerto km 2.5, Tapachula 30700, Chiapas, Mexico.
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Cruz-López
authors.affiliation: IRBI, Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Université François Rabelais, 37200 Tours, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Lenoir
authors.affiliation: El Colegio de la Frontera Sur, Av. Centenario km 5.5, Chetumal 77014, Quintana Roo, Mexico; Centre de Recherches sur la Cognition Animale, CNRS-UMR 5169, Université de Toulouse UPS, 118 route de Narbonne, 31062 Toulouse Cedex 09, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Lachaud
mesh_terms: D000374:Aggression; D000818:Animals; D001000:Ants / Q000469:parasitology* / Q000502:physiology; D005260:Female; D006586:Hexanes / Q000737:chemistry; D006790:Host-Parasite Interactions; D006838:Hydrocarbons / Q000737:chemistry*; D008297:Male; D009425:Nesting Behavior; D013045:Species Specificity; D014863:Wasps / Q000737:chemistry* / Q000502:physiology
chemical_list: D006586:Hexanes; D006838:Hydrocarbons
keywords: Chemical deception; Cuticular hydrocarbons; Ectatomma; Eucharitidae; Formicidae; Nestmate recognition