Search

Ectatomma opaciventre Roger is a species of ant whose prey includes species of flies, however, the behaviors employed by workers in their predation were not known. In this article, an ethogram of predation on larvae and adults of the fly Hermetia illucens L. by workers of E. opaciventre was elaborated. Individuals were collected from three E. opaciventre nests and later transferred to artificial nests. For each of them, live fly larvae and adults were offered. From the observations, in a context of predation, observed behaviors that had similar functions were grouped into categories, with four of them having been observed in predation on larvae and all eight in predation on adults. The larvae were not actually preyed on (the aggressive behavior performed by the ants appears to be related to nest defense), but the adult flies, in fact, served as food. [ABSTRACT FROM AUTHOR]

A diversity of arthropods (myrmecophiles) thrives within ant nests, many of them unmolested though some, such as the specialized Eucharitidae parasitoids, may cause direct damage to their hosts. Ants are known to discriminate between nestmates and non-nestmates, but whether they recognize the strength of a threat and their capacity to adjust their behavior accordingly have not been fully explored. We aimed to determine whether Ectatomma tuberculatum ants exhibited specific behavioral responses to potential or actual intruders posing different threats to the host colony and to contribute to an understanding of complex ant-eucharitid interactions. Behavioral responses differed significantly according to intruder type. Ants evicted intruders that represented a threat to the colony’s health (dead ants) or were not suitable as prey items (filter paper, eucharitid parasitoid wasps, non myrmecophilous adult weevils), but killed potential prey (weevil larvae, termites). The timing of detection was in accordance with the nature and size of the intruder: corpses (a potential source of contamination) were detected faster than any other intruder and transported to the refuse piles within 15 min. The structure and complexity of behavioral sequences differed among those intruders that were discarded. Workers not only recognized and discriminated between several distinct intruders but also adjusted their behavior to the type of intruder encountered. Our results confirm the previously documented recognition capabilities of E. tuberculatum workers and reveal a very fine-tuned intruder discrimination response. Colony-level prophylactic and hygienic behavioral responses through effective removal of inedible intruders appears to be the most general and flexible form of defense in ants against a diverse array of intruders. However, this generalized response to both potentially lethal and harmless intruders might have driven the evolution of ant-eucharitid interactions, opening a window for parasitoid attack and allowing adult parasitoid wasps to quickly leave the natal nest unharmed. [ABSTRACT FROM AUTHOR]

Ectatomma tuberculatum has one of the most toxic venoms known among ants but there is no detailed study on its characteristics. In light of this, knowing the venom’s chemical composition is of paramount importance in order to obtain information about the mechanisms of its components. Several bioactive molecules have already been identified in Hymenoptera venoms, i.e., proteins such as phospholipases, hyaluronidases, and proteinases, as well as peptides. Protein databases show that information on protein components of ant venoms has been recently growing exponentially. In this study, we have identified proteins from the venom of Ectatomma tuberculatum by means of 2D PAGE, followed by tandem nanochromatography with mass spectrometry. A total of 48 proteins were identified, of which 42 are involved in metabolic processes, transport, and structural support. Moreover, six of them show similarity with not yet characterized proteins. Nine proteins are related to the attack/defense or maintenance process of the colony (colony asepsis, conservation of venom constituents, venom diffusion on prey, paralysis of prey, alteration of homeostasis, and cellular toxicity). Our findings may contribute to the identification of new natural prototypes of molecules to be synthesized and used in several areas of pharmacology. [ABSTRACT FROM AUTHOR]

In the ant Ectatomma tuberculatum (Olivier 1792), workers have active ovaries and lay trophic eggs that are eaten by the queen and larvae. Vitellogenins are the main proteins found in the eggs of insects and are the source of nutrients for the embryo in the fertilized eggs and for adults in the trophic eggs. In social insects, vitellogenin titres vary between castes and affect reproductive social status, nursing, foraging, longevity, somatic maintenance, and immunity. In most insects, vitellogenin synthesis is mainly regulated by juvenile hormone. However, in non-reproductive worker ants, this relationship is poorly characterized. This study determined the effects of juvenile hormone on vitellogenin synthesis in non-reproductive E. tuberculatum workers. Juvenile hormone was topically applied onto workers, and the effect on vitellogenin synthesis in the fat body and vitellogenin titres in the haemolymph were analysed by ELISA and qPCR. Juvenile hormone downregulated protein synthesis and reduced vitellogenin titres in the haemolymph, suggesting that in workers of E. tuberculatum, juvenile hormone loses its gonadotrophic function. [ABSTRACT FROM AUTHOR]

Cognitive abilities used by arthropods, particularly predators, when interacting in a natural context have been poorly studied. Two neotropical sympatric predators, the golden silk spider Nephila clavipes and the ectatommine ant Ectatomma tuberculatum, were observed in field conditions where their interactions occurred regularly due to the exploitation of the same patches of vegetation. Repeated presentations of E. tuberculatum workers ensnared in their web triggered a progressive decrease in the capture response of N. clavipes. All the spiders that stopped trying to catch the ant on the second and/or third trial were individuals that had been bitten during a previous trial. Behavioural tests in natural field conditions showed that after a single confrontation with ant biting, spiders were able to discriminate this kind of prey more quickly from a defenceless prey (fruit flies) and to selectively and completely suppress their catching response. This one-trial aversive learning was still effective after 24 h. Likewise, E. tuberculatum workers entangled once on a N. clavipes web and having succeeded in escaping, learned to escape more quickly, breaking through the web by preferentially cutting spiral threads (sticky traps) rather than radial threads (stronger structural unsticky components) or pursuing the cutting of radials but doing it more quickly. Both strategies, based on a one-trial learning capability, obviously minimize the number of physical encounters between the two powerful opponents and may enhance their fitness by diminishing the risk of potential injuries resulting from predatory interactions. [ABSTRACT FROM AUTHOR]

Among social parasites, workerless inquilines entirely depend on their host for survival and reproduction. They are usually close phylogenetic relatives of their host, which raises important questions about their evolutionary history and mechanisms of speciation at play. Here we present new findings on Ectatomma parasiticum, the only inquiline ant described in the Ectatomminae subfamily. Field data confirmed its rarity and local distribution in a facultative polygynous population of E. tuberculatum in Mexico. Genetic analyses demonstrated that the parasite is a sibling species of its host, from which it may have diverged recently. Polygyny is suggested to have favored the evolution of social parasite by sympatric speciation. Nevertheless, host workers from this population were able to discriminate parasites from their conspecifics. They treated the parasitic queens either as individuals of interest or as intruders, depending on their colonial origin, probably because of the peculiar chemical profile of the parasites and/or their reproductive status. We suggest that E. parasiticum could have conserved from its host sibling species the queen-specific substances that produce attracting and settling effect on workers, which, in return, would increase the probability to be detected. This hypothesis could explain the imperfect social integration of the parasite into host colonies. [ABSTRACT FROM AUTHOR]

The boll weevil (Anthonomus grandis Boheman) remains a devastating insect pest on cotton (Gossypium hirsutum C. Linnaeus), particularly where it has not been eradicated. Identifying and understanding the survival of overwintered boll weevils, when cotton is not available, is important in designing mitigation programs and controlling this insect pest, especially in areas where boll weevils are active all year. Many non-malvaceous taxa have been listed as possible overwintering adult food sources. The purpose of this research was to determine if pollen from three non-malvaceous taxa could be used as food sources for overwintering boll weevils in the Lower Rio Grande Valley of Texas, where weevils are active year-round and during cotton-free periods. The taxa are almond [Prunus dulcis (Mill.) D.A. Webb], melon (Cucumis melo C. Linnaeus subsp. melo), and pigweed (Amaranthus sp.), Furthermore, it was intended to determine the retention of these pollen types in the boll weevil gut. More weevils (84%) contained almond pollen when they had additional water than those (30%) that did not have additional water. Almond pollen was found in 100% of the examined weevils after 72 hours, and in 80% after 96 hours. Pigweed and melon pollen were never found after 48 hours. Overall, almond pollen was found in more weevils (96%) than pigweed (40%), or melon (12%). In addition, a greater number of almond pollen grains (539) were found than pigweed (41), or melon (21). This shows that these types of pollen were consumed, and could play a part in the survival of overwintering weevils. However, more research is needed to examine the nutritional value of these, and other, pollen grains for overwintering boll weevil survival, and to determine the length of time weevils can survive feeding on these pollen types. [ABSTRACT FROM AUTHOR]

Social parasites exploit the worker force of colonies of other social insects to rear their own young. Social parasitism occurs in several Hymenoptera and is particularly common in several tribes of the ant subfamilies Myrmicinae and Formicinae. Here, we document the occurrence of miniaturized queens (microgynes) in colonies of Ectatomma tuberculatum, an ant belonging to the subfamily Ectatomminae. Behavioral observations and genetic analyses show that microgynes concentrate their reproductive efforts almost exclusively on the production of sexual offspring (microgynes and males), whereas the regular, large queens (macrogynes) produce workers in addition to sexuals. According to mitochondrial and nuclear markers, gene flow between microgynes and macrogynes is extremely limited. Whereas the co-occurrence of microgynes and macrogynes in the related species Ectatomma ruidum constitutes an intraspecific polymorphism associated with alternative dispersal tactics, microgynes found in colonies of E. tuberculatum appear to be a distinct species and to represent the first case of social parasitism in the poneromorph subfamilies of ants. [ABSTRACT FROM AUTHOR]

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). [Copyright &y& Elsevier]

Analyzes the effect of Ectatomma tuberculatum toxin on cell membranes. Containment of homologous polypeptide chains; Intracellular distribution of ectatomin; Determination of the amino acid sequence and spatial structure of the toxin.

Social insects exhibit a great variability in their social organization, and this affects colony kin structure, relatedness among nest mates, and population genetic structure. In the mosaic of arboreal ants of neotropical habitats, mutually exclusive dominant ant species occupy different territories, and their nest distribution is spatially aggregated in patches influencing patterns of population genetic structure. In this study, we performed an analysis of the population and colony genetic structure of the facultative polygynous ant Ectatomma tuberculatum to investigate how the particular breeding and social system of this species can explain its ecological dominance in the mosaic. Within-nest genetic analysis revealed that relatedness between nest mate workers was significantly greater than zero (r = 0.30) with an effective number of queens per nest of Ne = 2.5–3, indicating that polygyny is functional in this species. Moreover, we found that queen number was highly variable, probably due to queen adoption events, leading to the prevalence of polygyny over monogyny. Finally, the strong population genetic structure and the significant isolation by distance suggested that both budding and polydomy take place in this species. The respective role of secondary polygyny, budding, and polydomy are then discussed in the context of the mosaic of arboreal ants, and we propose that this particular social organization ensures the ecological dominance of E. tuberculatum by optimizing the colonization of new available nesting sites and by increasing territory size. [ABSTRACT FROM AUTHOR]