The spatial distribution does not affect host–parasite coevolution in <Emphasis Type="Italic">Rossomyrmex</Emphasis> ants

Host and parasite distributions are crucial to understand the coevolutionary outcomes of their relationships. This comes from the fact that the distribution of a species (fragmented vs. continuous habitats) influences its dispersal opportunities. In this work, we studied the effect of the spatial distribution on dispersal and coevolution between three species of social parasite ants of the genus Rossomyrmex (one distributed in high mountains in Spain and two distributed in extended plains in Turkey and Kazakhstan) and their ant hosts Proformica. We analysed the variation at the mitochondrial gene cytochrome c oxidase (COI) to infer female dispersal for parasites as well as the cuticular hydrocarbons (CHCs) of parasites and hosts to study their coevolutionary process, given that CHCs are involved in nestmate recognition. Our genetic results revealed a surprising scarce variation at COI for the three parasite species, suggesting selective forces that prevent from mutation fixation. Therefore, COI appeared to be a poor tool to study dispersal. Furthermore, chemical results showed population differentiation for all host–parasite systems, pointing that coevolution would take place at a local scale regardless of the spatial distribution or dispersal opportunities of the counterparts.     

Nest-moving by the polydomous ant <Emphasis Type="Italic">Cataglyphis iberica</Emphasis>

In this paper we analyze emigration from nests by the polydomous ant Cataglyphis iberica. Social carrying of workers of this species between different nests of the colony is frequent. In Bellaterra (Barcelona, NE Spain), we monitored field emigration of C. iberica by noting for each nest the migratory behavior of C. iberica workers and, when the nests were attacked by another ant species, Camponotus foreli, we noted the number of C. foreli workers involved in the attacks. Emigration of C. iberica from nests was highly variable. We suggest the main factor determining emigration by this species was attack by workers of C. foreli, so emigration from C. iberica nests was much faster when harassment by C. foreli increased. The system of multiple nests of C. iberica enables this species to abandon attacked nests and to reinstall their population in other nests of the same colony. This reduces risk to the colonies because the route between the different nests is well known by transporter workers.     

Early learning of volatile chemical cues leads to interspecific recognition between two ant species

Nestmate recognition in social insects generally involves matching a label to the template that is acquired through the early learning of non-volatile cuticular hydrocarbon cues. However, a possible role of the volatile chemical cues that exist in the nest, and which may also affect template formation, has not been studied. We investigated this possibility using experimental mixedspecies groups composed of the two ant species Manica rubida and Formica selysi. The experimental set-up either allowed full contact between workers of the two species or interspecific contact was hindered or prohibited by a single or a double mesh. After three months, workers of M. rubida ants were selected as focal ants for aggression tests including the following target ants: F. selysi workers from the same mixed-species group (for each of the three rearing conditions) or from a single-species group (control). Workers of M. rubida were always amicable towards their group-mates, irrespective of the experimental group (contact, single or double mesh). However, M. rubida that were not imprinted on F. selysi, expressed high levels of aggression towards the non-familiar F. selysi workers. The finding that F. selysi workers in the mixed-species groups appeared familiar to their M. rubida group-mates even without physical contact between them, suggests that the volatile cues produced by F. selysi affected nestmate recognition in M. rubida. In an attempt to identify these volatile cues we performed SPME analysis of the head space over groups of F. selysi workers. The findings revealed that F. selysi Dufour’s gland constituents, with undecane as the major product, are released into the head space, rendering them likely candidates to affect template formation in M. rubida. Analysis of Dufour’s gland secretion of F. selysi revealed a series of volatile alkanes, including undecane as a major product. These alkanes were not present in the glandular secretion of M. rubida, whose secretion was mainly composed of isomers of farnesene. We therefore hypothesize that callow M. rubida workers in the mixed-species groups had become imprinted by the above alkanes (in particular undecane, being the major heterospecific volatile in the head space) and incorporated them into their own template. Received 18 October 2007; revised 2 January 2008; accepted 7 January 2008.     

Preliminary biological evaluations of new thalidomide analogues for multiple sclerosis application

The present work deals with the synthesis of a new series of thalidomide derivatives for therapeutic applications. These compounds were evaluated in vitro on a human endothelial cell line EA.hy926 for their antiproliferative potential and in vivo on an experimental animal multiple sclerosis model called EAE as angiogenesis inhibitors. The preliminary results obtained on EAE assays seem to validate that anti-angiogenesis compounds could be promising tools for the treatment of MS.     

Ontogeny of hydrocarbon profiles in the ant Aphaenogaster senilis and effects of social isolation

In ants, cuticular hydrocarbons are used for nestmate recognition; they are stored in the postpharyngeal gland and shared among the individuals. Newly emerged ants have a very small quantity of hydrocarbons. We studied the ontogeny of the hydrocarbon profile in Aphaenogaster senilis. The total quantities of both cuticular and postpharyngeal gland (PPG) hydrocarbons increased with age from 0 to 20 days after emergence and then stabilised. These quantities are correlated with the development of the ovary. Under individual social isolation, cuticular hydrocarbons increased as normal, but the total quantity of PPG hydrocarbons never increased from the initial low level. This effect of social isolation on the PPG hydrocarbon level indicates the importance of hydrocarbon transfer between nestmates through the PPG and lends support to the gestalt model of nestmate recognition. To cite this article: K. Ichinose, A. Lenoir, C. R. Biologies 332 (2009).     

Blochmannia endosymbionts improve colony growth and immune defence in the ant Camponotus fellah

Background  

Microorganisms are a large and diverse form of life. Many of them live in association with large multicellular organisms, developing symbiotic relations with the host and some have even evolved to form obligate endosymbiosis [1]. All Carpenter ants (genus Camponotus) studied hitherto harbour primary endosymbiotic bacteria of the Blochmannia genus. The role of these bacteria in ant nutrition has been demonstrated [2] but the omnivorous diet of these ants lead us to hypothesize that the bacteria might provide additional advantages to their host. In this study, we establish links between Blochmannia, growth of starting new colonies and the host immune response.     

Effects of ants on plant diversity in semi-natural grasslands

Ants (L. niger and L. flavus) build conspicuous mounds that are covered with vegetation. The aim of this study was to investigate whether the vegetation on ant mounds in semi-natural grasslands differed from that around the mounds. Another aim was to investigate whether the changes in the vegetation on ant mounds were influenced by grazing management or by habitat characteristics, semi-dry versus moist. Here, the total number of plant species and total plant cover were lower on ant mounds than in patches off-mound. The plant cover of perennials that form rosettes was twice as high on mounds inhabited by L. niger than on those inhabited by L. flavus. Only a few plant species were restricted to either ant mounds or adjacent field and the effects of ants on the plant diversity in semi-natural grasslands seemed to be low. Grazing management did not affect the differences in the vegetation on ant mounds and in equal-sized patches off-mound, whereas habitat characteristics affected ant-induced changes in vegetation cover of some plant species.