4 research outputs found
Consistently high incidence of Wolbachia in global fig wasp communities
1. Wolbachia are very common and widespread endosymbionts of arthropods. They can
have a considerable effect on their host's fitness. It has been estimated that as many as
40% of arthropod species are infected with Wolbachia, but particular taxonomic groups
and ecological niches display significantly higher or lower incidences.
2. In this study, we combine an African sample with those of three previous studies from
three other continents. We reanalyzed Wolbachia incidence in 172 fig wasp species
(including pollinators, non pollinators, gallers and non gallers) associated with 81 fig
trees of six subgenera, and estimated that > 80% of fig wasp species are infected with
Wolbachia, which is far higher than putative global infection rates in arthropods.
3. We found that, within fig wasps, incidence does not vary consistently with respect to host
taxonomy, ecology or geography. In particular, incidence seems remarkably constant
across samples from different geographical locations.University of Pretoriahttp://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2311hb201
Inactivation of Wolbachia reveals its biological roles in whitefly host
BACKGROUND: The whitefly Bemisia tabaci is cryptic species complex composed of numerous species. Individual species from the complex harbor a diversity of bacterial endosymbionts including Wolbachia. However, while Wolbachia is known to have a number of different roles, its role in B. tabaci is unclear. Here, the antibiotic rifampicin is used to selectively eliminate Wolbachia from B. tabaci so as to enable its roles in whitefly development and reproduction to be explored. The indirect effects of Wolbachia elimination on the biology of Encarsia bimaculata, a dominant parasitoid of B. tabaci in South China, were also investigated. METHODOLOGY/PRINCIPAL FINDING: qRT-PCR and FISH were used to show that after 48 h exposure to 1.0 mg/ml rifampicin, Wolbachia was completely inactivated from B. tabaci Mediterranean (MED) without any significant impact on either the primary symbiont, Portiera aleyrodidarum or any of the other secondary endosymbionts present. For B. tabaci MED, Wolbachia was shown to be associated with decreased juvenile development time, increased likelihood that nymphs completed development, increased adult life span and increased percentage of female progeny. Inactivation was associated with a significant decrease in the body size of the 4th instar which leads us to speculate as to whether Wolbachia may have a nutrient supplementation role. The reduction in nymph body size has consequences for its parasitoid, E. bimaculata. The elimination of Wolbachia lead to a marked increase in the proportion of parasitoid eggs that completed their development, but the reduced size of the whitefly host was also associated with a significant reduction in the size of the emerging parasitoid adult and this was in turn associated with a marked reduction in adult parasitoid longevity. CONCLUSIONS/SIGNIFICANCE: Wolbachia increases the fitness of the whitefly host and provides some protection against parasitization. These observations add to our understanding of the roles played by bacterial endosymbionts.This research was funded by the National Basic Research Program of China (2009CB119203), the Program for New Century Excellent Talents in
University (NCET-0917–2011) and the China National Natural Science Foundation (31071732).http://www.plosone.or
Evidence for horizontal transmission of secondary Endosymbionts in the Bemisia tabaci cryptic species complex
Bemisia tabaci (Hemiptera: Aleyrodidae) is a globally distributed pest composed of at least 34 morphologically
indistinguishable cryptic species. At least seven species of endosymbiont have been found infecting some or all members of
the complex. The origin(s) of the associations between specific endosymbionts and their whitefly hosts is unknown.
Infection is normally vertical, but horizontal transmission does occur and is one way for new infections to be introduced into
individuals. The relationships between the different members of the cryptic species complex and the endosymbionts have
not been well explored. In this study, the phylogenies of different cryptic species of the host with those of their
endosymbionts were compared. Of particular interest was whether there was evidence for both coevolution and horizontal
transmission. Congruence was observed for the primary endosymbiont, Portiera aleyrodidarum, and partial incongruence in
the case of two secondary endosymbionts, Arsenophonus and Cardinium and incongruence for a third, Wolbachia. The
patterns observed for the primary endosymbiont supported cospeciation with the host while the patterns for the secondary
endosymbionts, and especially Wolbachia showed evidence of host shifts and extinctions through horizontal transmission
rather than cospeciation. Of particular note is the observation of several very recent host shift events in China between
exotic invader and indigenous members of the complex. These shifts were from indigenous members of the complex to the
invader as well as from the invader to indigenous relatives.The Program for New Century Excellent Talents in University 2011, National Basic Research Program of China (973 Project,
2009CB119203) and the China National Natural Science Foundation (31071732).http://www.plosone.orgam201
Genetic networking of the Bemisia tabaci cryptic species complex reveals pattern of biological invasions
BACKGROUND: A challenge within the context of cryptic species is the delimitation of individual species within the complex.
Statistical parsimony network analytics offers the opportunity to explore limits in situations where there are insufficient
species-specific morphological characters to separate taxa. The results also enable us to explore the spread in taxa that have
invaded globally.
METHODOLOGY/PRINCIPAL FINDINGS: Using a 657 bp portion of mitochondrial cytochrome oxidase 1 from 352 unique
haplotypes belonging to the Bemisia tabaci cryptic species complex, the analysis revealed 28 networks plus 7 unconnected
individual haplotypes. Of the networks, 24 corresponded to the putative species identified using the rule set devised by
Dinsdale et al. (2010). Only two species proposed in Dinsdale et al. (2010) departed substantially from the structure
suggested by the analysis. The analysis of the two invasive members of the complex, Mediterranean (MED) and Middle East
– Asia Minor 1 (MEAM1), showed that in both cases only a small number of haplotypes represent the majority that have
spread beyond the home range; one MEAM1 and three MED haplotypes account for .80% of the GenBank records. Israel is
a possible source of the globally invasive MEAM1 whereas MED has two possible sources. The first is the eastern
Mediterranean which has invaded only the USA, primarily Florida and to a lesser extent California. The second are western
Mediterranean haplotypes that have spread to the USA, Asia and South America. The structure for MED supports two home
range distributions, a Sub-Saharan range and a Mediterranean range. The MEAM1 network supports the Middle East - Asia
Minor region.
CONCLUSION/SIGNIFICANCE: The network analyses show a high level of congruence with the species identified in a previous
phylogenetic analysis. The analysis of the two globally invasive members of the complex support the view that global
invasion often involve very small portions of the available genetic diversity.M.Z. Ahmed thanks University of Pretoria for awarding him a Commonwealth scholarship to support his doctoral studies.http://www.plosone.or