|The Ants of Africa
The Doyle Mckey 2001 Wolbachia project in Cameroun
Dear Professor Taylor,
I would like to enlist you as a co-author in a highly original study we are conducting.
First, I want to tell you why we feel this project merits your attention, and why we need your collaboration, in the form of determining the ants involved. The study is a survey (in tropical Africa) of the occurrence of the bacteria Wolbachia in two groups of social insects, ants and termites. The 3 objectives of this study are to (i) determine the distribution and type of Wolbachia in a sample of Cameroonian ants, (ii) survey for the first time another group of eusocial insects, termites, for Wolbachia, and (iii) compare the results of this survey to the previous studies, in particular to one which focused on south-east Asian ant species (see below).
These endoparasitic bacteria (related to Rickettsia), which tend to localise in the gonads of the host, have very unusual and interesting biological traits. They infect the reproductive tissues, mainly of arthropods, are transmitted through the egg cytoplasm and alter reproduction in their hosts in various ways (Werren 1997). Themselves cytoplasmically (and thus maternally) transmitted, they increase their own transmission, and evolutionary fitness, by inducing sex ratio biases via cytoplasmic incompatibility (in particular between a male and a female mate that are infected by two different and incompatible strains of Wolbachia), parthenogenesis, feminisation of genetic males, or male killing. Their effects on sex expression in haplodiploid hosts is unknown. The potential impact of such organisms in affecting the biology of social insects is obviously enormous.
Despite their potential importance, demonstrated in a few key studies (Werren 1997: alteration of reproduction; Werren 1998: links between Wolbachia and speciation in arthropods), few broad surveys have been conducted for the presence of Wolbachia in insects. Three studies considered the whole group of insects [Werren et al. 1995: insect species of lower Central America (Panama); West et al. 1998: insect species of northern Europe (Britain); Werren & Windsor 2000: insect species of temperate North America], and one focused on south-east Asian ant species (Wenseleers et al. 1998). Wolbachia appear so far to be most frequent in Hymenoptera and Lepidoptera. The study of Wenseleers et al. (1998) uncovered an interesting trend: Wolbachia seemed less frequently present in species whose queens always independently found colonies, than in species with secondary polygyny, in which some queens join established colonies. This would be in accord with theoretical expectations of greater instability of the association when, for example, foundations fail because the sole queen is sterile. A broader survey of Wolbachia presence could well turn up many other leads to follow in the long-term goal of determining the biological effects of Wolbachia infection.
My two Ph.D. students working on population genetics of ants associated with Leonardoxa, Gabriel Debout (on Cataulacus mckeyi) and Ambroise Dalecky (Petalomyrmex phylax), are collaborating with a specialist on Wolbachia, Dr. Frédéric Fleury (Université Lyon I, France), who has found, using specific molecular markers, that Wolbachia are ubiquitous in these two species. Dr. Fleury is interested in collaborating in a broad survey, and Gabriel and Ambroise, during their last field trip to Cameroon in March-April 2001, collected about 70 samples of ants and 20 of termites for such a survey. The attached list gives our tentative identifications, so far as they go.
They have already contacted Dr. Paul Eggleton (British Museum of Natural History) to ask if he would be willing to identify the termites they collected, and we are asking if you would be interested in determining the ants. We can supply you with series of workers, at the very least, and in some cases with alates and brood as well. We could also include in this survey ants from other sources you may know of, to increase the representativity of the sample. The material must be relatively recently collected (no older than 2-3 years), and simply preserved in 95% ethanol.
We hope you are sufficiently intrigued by this project to decide that it is worth your time. In any event, we look forward to hearing from you and obtaining any suggestions you may have.
Professor, Université Montpellier II, France
Wenseleers T., Ito F., Van Borm S., Huybrechts R., Volckaert F., and Billen J. 1998. Widespread occurrence of the micro-organism Wolbachia in ants. Proc. R. Soc. Lond. B 265: 1447-1452.
Werren J.H., Windsor D. & Guo L. 1995. Distribution of Wolbachia among Neotropical arthropods. Proc. R. Soc. Lond. B 262: 197-204.
Werren J.H. 1997. Biology of Wolbachia. Annu. Rev. Entomol. 42: 587-609.
Werren J.H. 1998. Wolbachia and speciation. In Endless forms : species and speciation (ed. D. Howard & S. Berlocher), pp. 245-260. Oxford University Press.
Werren J.H. and Windsor D.M. 2000. Wolbachia infection frequencies in insects: evidence of a global equilibrium? Proc. R. Soc. Lond. B 267: 1277-1285.
West S.A., Cook J.M., Werren J.H. & Godfray H.C. 1998. Wolbachia in two insect-host-parasitoid communities. Mol. Ecol. 7: 1457-1465.
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©2001 - Brian Taylor CBiol FSB FRES
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