Conservación de la Biodiversidad

Paltothyreus tarsatus workers show an adaptive predatory strategy compatible with central place theory which predicts that single-prey loading is an extension of the optimal diet choice while multiple-prey loading behavior would correspond to the optimal use of patches. The insight learning involved in the quick modifications of predatory strategy enables P. tarsatus to hunt all available prey in a great diversity of sizes and spe-

The following new recent species of mermithid (Nematoda) parasites of Neotropical ants are described: Meximermis ectatommi n.gen., n. sp. from workers of Ectatomma ruidum Roger in Southern Mexico, Agamomermis cephaloti n. sp. from a worker of Cephalotes minutus (Fab.) collected in Brazil, Agamomermis ecitoni n. sp. from a worker of Eciton burchellii Westwood collected in Venezuela and Agamomermis costaricensis n. sp. from a worker of Odontomachus hastatus (Fab.) collected in Costa Rica. In addition, a fossil mermithid parasite of a worker of Linepithema sp. from Dominican amber is described as Heydenius myrmecophila n. sp. These parasites represent the first descriptions of Neotropical ant mermithids and together with previous records listed here, show that ant infection by mermithids in the Neotropics is widespread and has occurred for at least 20–30 million years.

The great flexibility of the feeding strategies exhibited by the ponerine ant Brachyponera senaarensis (Mayr) allows it to exploit either seeds or animal prey items as food resources. Predation is generally limited to small prey and is very similar to scavenging behavior. In laboratory conditions, the predatory behavior of B. senaarensis is not different in structure from that known in other carnivorous ants species. The workers forage individually and return to the nest using a series of cues involving light, a chemical graduated marking system near the nest entrance, and memory. During nest-moving, recruitment by tandem running was observed. However, in colonies where the food supply is regular, workers that discover food do not recruit nestmates, but make repeated trips between the nest and the food source.

This study reports new information on interactions between Ectatomma tuberculatum (Ponerinae) and Crematogaster limata parabiotica (Myrmicinae). Workers of these sympatric arboreal ant species forage on the same pioneer trees. Diurnally, Ectatomma preyed on Crematogaster workers that avoided overt aggression by respecting a 'safe distance'. At night, Crematogaster initiated raids within the Ectatomma nests that they apparently left with their abdomen empty, then remained near the nest entrances where they successfully intercepted 75.2% of the returning Ectatomma foragers (N = 322). Certain intercepted workers rapidly resumed their return trip. Others (39.1%) were stopped, explored and licked during a long time by the Crematogaster. Most of them were carrying between their mandibles a droplet of liquid food that was stolen. This relationship, that appears to be a typical case of interspecific cleptobiosis, whose expression varies during the daytime, demonstrates for the first time sugary-food robbing, instead of prey robbing, in ants. To cite this article: F.-J. Richard et al., C. R. Biologies 327 (2004).  2004 Académie des sciences. Published by Elsevier SAS. All rights reserved.

We investigated how the formicine ant Gigantiops destructor can use vector information to navigate within the cluttered environment of the rain forest. Displaced foragers use skylight information to move in the theoretical feeder-to-nest direction, whether they are prevented from updating their path-integrator during foraging or captured at the departure from their nest, i.e. with a current accumulator state very close to zero. Only ants that have collected food are able to download a long-term stored reference vector pointing in the nest direction, irrespective of the current accumulator state of their path-integrator stored in a working memory and independent of familiar landmarks. Depending on the release sites, ants that became lost at a maximum distance of 50 cm could still hit and recognize their familiar route, or they engaged in a systematic search for it centered on the release sites. In contrast to Cataglyphis desert ants, Gigantiops ants do not rely primarily on the current accumulator state of their egocentric path integrator. Such a long-term vector-based navigation primed by food capture is well adapted for a tropical ant foraging during periods spanning several hours. This could prevent the numerous cumulative errors in the evaluation of the angles steered that might result from a continuously running path-integrator operating during complex foraging patterns performed at ground or arboreal levels and during passive displacement in response to heavy rain.

Kapala (Hymenoptera: Eucharitidae) are among the most frequently collected chalcidoid wasps from the Neotropics, but general information about their host plants, behavior, and life history is scarce. A new species, Kapala izapa n. sp., parasitizing Ectatomma ruidum Roger (Hymenoptera: Formicidae), is described from Chiapas, Mexico, with a general account of its biology. Field observations on the behavior of adults of Kapala iridicolor (Cameron), which also attack E. ruidum, Gnamptogenys regularis Mayr, Gnamptogenys sulcata (Fr. Smith), Gnamptogenys striatula Mayr, and Pachycondyla stigma (F.) (Hymenoptera: Formicidae), are included. Immature stages of Kapala izapa n. sp. follow the general morphology and behavior described for other eucharitids known to attack Ectatomminae and Ponerinae. More than one parasitoid can complete development on a single host larva. K. iridicolor females were observed laying masses of eggs on undeveloped ßower buds of Melampodium divaricatum (L.C. Richard) D.C. (Asteraceae). Extraßoral nectaries of this plant are visited by several insects, including predatory foraging worker ants of E. ruidum. Dissection of recently emerged females of K. iridicolor yielded Ϸ4,500 fully developed eggs.

Cuticular hydrocarbons from the ponerine ant Ectatomma ruidum Roger and a highly integrated eucharitid myrmecophile, Kapala sulcifacies (Cameron), associated with it, have been characterized. Ninety hydrocarbons were identiÞed from the ant, 55 hydrocarbons from the female wasp and 54 hydrocarbons from the male wasp. The wasps and ants share 40 hydrocarbons. These shared 40 hydrocarbons represent 92.6% of their hydrocarbon composition for female Kapala, 84.3% for male Kapala and 67.7% for the ants. The wasps have a carbon number range of C 27 to C 35 ; the ants have a range of C 23 to C 35 . Both species possess n-alkanes, C 27 to C 33 for the wasps, C 23 to C 34 for the ants. Both species also possess major quantities of Z-7-and Z-9 alkenes: C 29 to C 33 for the wasps; C 23 to C 35 for the ants. The female wasps possess a low amount of a conjugated C 31 diene (neither the ants nor the male wasps possess this hydrocarbon), and the ants, but not the wasps, contain low quantities of nonconjugated dienes (carbon numbers of C 23 to C 29 ) with double bonds at ⌬ 9 , and ⌬ 14 . Both wasps and ants share homologous series of 3-, 5-, 10-, 11-, 12-, 13-, 15-and 17-methyl branched alkanes. Ants and wasps also share a homologous series of 3,7-dimethyl alkanes. Other internally branched dimethyl alkanes are found in both ants and wasps, but only 11, 15-DiMeC 29 is shared. Wasps have 7, 15-and 10, 14-dimethyl alkanes while the ants have 15,19-dimethyl alkanes. Kapala sulcifacies and E. ruidum both possess hydrocarbons of the 5, X-, 11, X-, 12, X-and 13, X-DiMe series, but the compounds involved are not shared because they represent different compounds. Behavioral observations indicate that the ants accept the newly emerged adult parasitoids with no evidence of agonistic behavior for a period of time after adult eclosion. Nevertheless, the chemical deception is not completely efÞcient because young adult Kapala are soon ejected from the nest by transportation by their host. These transportations frequently occur after seizure at the base of the waspsÕ characteristic scutellar spines, such structures allowing for easy transportation without injury for the parasite. Moreover, if no method of escaping the colony is provided, the ants ultimately attack the parasitoids. The substantial chemical overlap of the cuticular hydrocarbon proÞles of the ants and wasps are discussed in the context of the social life of the colony.

and 4 Addresse pour correspondance (Accept&e le 18 juin 1990) Resume Treize colonies de Dinoponera quadriceps ont &C Ctudiees sur le terrain au BrCsil. La dissection de toutes les ouvrieres montre que chaque ouvriere possede des ovaires a 6 ovarioles par ovaire ainsi qu'une spermatheque. De plus, la continuite des stades physiologiques ovariens chez les ouvrieres est remarquable. La ponte est realisee par des ouvrieres fecondees (= les "gamergates") mais aussi par quelques ouvrieres non fecondees qui presentent des ovaires completement developppes renfermant de nombreux ovocytes et des inclusions de corps jaunes. Par ailleurs, quelques gamergates presentent des ovaires incompletement developpb ne leur permettant pas d'intervenir effectivement dans la reproduction avant que ceux-ci n'atteignent leur complet developpement. Le rale a la fois de I'insemination et des processus de maturation lies a I'Pge dans la differentiation du statut de reproductrice et de non reproductrice est discute. Abstract Thirteen colonies of Dinoponera quadriceps were studied in the field in Brazil. Dissection of all workers showed that each worker has ovaries with 6 ovarioles/ovary 0376-6357/90/$03.50 0 1990 Elsevier Science Publishers B.V. (Biomedical Division) 102 and a functional spermatheca. Moreover, the continuity of ovarian physiological states among workers is remarkable. Egg laying is perfomred by mated workers (= gamergates) but also by few unmated ones exhibiting completely developed ovaries with numerous oocytes and yellow bodies inclusions. Besides, some gamergates present uncompletely developed ovaries and thus cannot be involved in egg laying until their ovaries reach full development. The role of both insemination and aging process in the differentiation between reproductive and non reproductive status is discussed.

In order to study both the hunting efficiency and the flexibility of their predatory behavior, solitary hunters of the trap-jaw ant Odontomachus opaciventris were offered small prey (termites, fruit flies and tenebrionid larvae), presenting different morphological or defensive characteristics. The monomorphic hunters showed a moderately flexible predatory behavior characterized by short capture sequences and a noteworthy efficiency of their mandible strike (76.7-100% of prey retrievals), even when presented with Nasutitermes soldiers. Contrary to most poneromorph ants, antennal palpation of the prey before the attack was always missing, no particular targeted region of the prey's body was preferred, and no 'prudent' posture was ever exhibited. Moreover, stinging was regularly performed on bulky, fast moving fruit flies, very scarcely with sclerotized tenebrionid larvae, but never occurred with Nasutitermes workers or soldiers despite their noxious chemical defense. These results suggest that, whatever the risk linked to potentially dangerous prey, O. opaciventris predatory strategy optimizes venom use giving top priority to the swiftness and strength of the lethal trap-jaw system used by hunters as first strike weapon to subdue rapidly a variety of small prey, ranging from 0.3 to 2 times their own body size and from 0.1 to 2 times their weight. Such risk-prone predatory behavior is likely to be related to the large size of O. opaciventris colonies where the death of a forager might be of lesser vital outcome than in small colony-size species.