Influence of symbionts on host niche and partner’s choices
Context and objectives
The processes underlying ecological speciation, i.e. the establishment of reproductive isolation between
divergent populations, is a central question in Biology and has been at the origin of intense debates
among evolutionary biologists. The fundamental question is to understand how reproductive isolation
can emerge as a consequence of divergent selection despite gene flow. The idea that symbiosis could be
a driver of speciation has been defended since the beginning of the 20th century. Symbiosis has been
associated with major transitions in evolution, notably in insects, where, for example, the acquisition of
nutritional obligate bacterial symbionts allowed phytophagous insects to feed on plant sap. In addition
to obligate symbionts, insects are often associated with a diversity of facultative endosymbionts that can
also play a role in the exploitation of the insect host niche and mating choice and could thus be associated
with rapid diversification.
The objective of this project is to investigate whether endosymbionts play a role in diversification
and ecological speciation of insect pests, and most notably in their use of cultivated plants and
partner’s choice. This study will be done on the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae), a
complex of morphologically indistinguishable species, whose taxonomy has been the subject of
important controversies. The most recent analyses, based on a threshold of 3.5% mitochondrial
cytochrome oxidase 1 gene sequence divergence, have identified 28 species in this complex. This
number has however to be taken with caution, as important mitochondrial variation is encountered in
some “species”. Whiteflies harbour several bacterial symbionts: in addition to their obligate symbiont,
95% of B. tabaci individuals are infected by one or more facultative symbionts. Importantly, symbiotic
composition is specific to each biotype and it is, in some cases, associated with particular biological and
ecological features such as host plant range, geographical localisation and insecticide resistance. This
raises the possibility that symbionts may play a role in the adaptation to environmental changes and the
diversification of the B. tabaci species complex. Interestingly, B. tabaci biotypes differ in their capacity
to transmit plant viruses, which seems to be linked to the composition of the bacterial symbiotic
community they harbour, a hypothesis that needs further experimental evidence.
Methodology
Mate choice tests will be performed using males and females harbouring different associations of
facultative symbionts. These same lines will also be used to measure insect attraction to different plants.
Insect performance will be measured through the analysis of life history traits like survival, fecundity
and metabolic capacities (by HPLC profiling of relevant metabolites). Molecular biology techniques
will be used to determine the symbiont composition of the different insect lines.
Skills
This project implies manipulation of tiny (1mm) and fast moving insects, it thus requires a student
having a strong interest in insect biology, and who possibly already worked on small insects. The
recruited student should also show interest in behavioural ecology.
Environment
Experiments will be realised in two laboratories located at the same university site, University of Lyon
(Villeurbanne, France), the Laboratory of Biometry and Evolutionary Biology (LBBE, UMR CNRS
5558, Université Lyon1) and the Laboratory of Functional Biology, Insects and Interactions (UMR
INRA/INSA de Lyon 203 BF2I). The supervision will be done by members of these two laboratories,
who are collaborating since several years and already supervised jointly students’ projects. The team
‘Genetics and Evolution of host-parasite interactions’ of the LBBE is recognized as a world leading
group in the field of insect symbiosis, notably on the evolution of host-symbiont and symbiont-symbiont
interactions. Its work on B. tabaci includes the evaluation of the diversity and effects of symbiotic
communities. The team ‘Trophic SYMbioses’ of the BF2I lab has long-standing knowledge of
nutritionally-based symbioses in insects. The team is internationally recognized for its expertise in the
physiology and metabolism of symbiotic insects, working since several years on pea aphid / Buchnera
aphidicola symbiotic system. The two teams belong to a multidisciplinary institute where
bioinformatics, ecology, genetics and medicine are studied, providing a stimulating and rich
environment.
Supervision
Laurence Mouton (laurence.mouton@univ-lyon1.fr), Federica Calevro (federica.calevro@insa-lyon.fr)
References
Romba R., Gnankiné O., Drabo SF., Tiendrebeogo F., Henri H., Mouton L. & Vavre F. Abundance of Bemisia tabaci Gennadius
(Hemiptera: Aleyrodidae) and its parasitoids on vegetables and cassava plants in Burkina Faso (West Africa). Ecology and
Evolution. In press.
Simonet P., Gaget K., Balmand S., Ribeiro-Lopes M., Parisot N., Buhler K., Duport G., Vulsteke V., Febvay G., Heddi A.,
Charles H., Callaerts P., Calevro F. (2018). Bacteriocyte cell death in the pea aphid/Buchnera symbiotic system. Proceedings
of the National Academy of Sciences USA 2018 Feb 5. Pii: 201720237. doi: 10:10.1073/pnas.1720237115.
Simonet P., Gaget K., Parisot N., Duport G., Rey M., Febvay G., Charles H., Callaerts P., Colella S., Calevro F. (2016)
Disruption of phenylalanine hydroxylase reduces adult lifespan and fecundity, and impairs embryonic development in
parthenogenetic pea aphids. Scientific Reports 6, 34321; doi: 10.1038/srep34321.
Mouton L., Gnankiné O. Henri H., Terraz G., Ketoh G., Martin T., Fleury F. & Vavre F. (2015). Detection of genetically
isolated entities within the Mediterranean species of Bemisia tabaci: new insights into the systematics of this worldwide
pest. Pest Management Science, 71: 452-458.
Mouton L., Gnankiné O., Henri H., Terraz G., Houndeté T., Martin T., Vavre F. & Fleury F. (2013). Distribution Bemisia
tabaci biotypes (Homoptera: Aleyrodidae) and their associated symbiotic bacteria on host plants in western Africa. Insect
Conservation and Diversity, 6: 411-421.
Rabatel A., Febvay G., Gaget K., Duport G., Baa-Puyoulet P., Sapountzis P., Bendridi N., Rey M., Rahbé Y., Charles H.,
Calevro F., Colella S. (2013) Tyrosine pathway regulation is host-mediated in the pea aphid symbiosis during late embryonic
and early larval development. BMC Genomics 14(1):235.
Context and objectives
The processes underlying ecological speciation, i.e. the establishment of reproductive isolation between
divergent populations, is a central question in Biology and has been at the origin of intense debates
among evolutionary biologists. The fundamental question is to understand how reproductive isolation
can emerge as a consequence of divergent selection despite gene flow. The idea that symbiosis could be
a driver of speciation has been defended since the beginning of the 20th century. Symbiosis has been
associated with major transitions in evolution, notably in insects, where, for example, the acquisition of
nutritional obligate bacterial symbionts allowed phytophagous insects to feed on plant sap. In addition
to obligate symbionts, insects are often associated with a diversity of facultative endosymbionts that can
also play a role in the exploitation of the insect host niche and mating choice and could thus be associated
with rapid diversification.
The objective of this project is to investigate whether endosymbionts play a role in diversification
and ecological speciation of insect pests, and most notably in their use of cultivated plants and
partner’s choice. This study will be done on the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae), a
complex of morphologically indistinguishable species, whose taxonomy has been the subject of
important controversies. The most recent analyses, based on a threshold of 3.5% mitochondrial
cytochrome oxidase 1 gene sequence divergence, have identified 28 species in this complex. This
number has however to be taken with caution, as important mitochondrial variation is encountered in
some “species”. Whiteflies harbour several bacterial symbionts: in addition to their obligate symbiont,
95% of B. tabaci individuals are infected by one or more facultative symbionts. Importantly, symbiotic
composition is specific to each biotype and it is, in some cases, associated with particular biological and
ecological features such as host plant range, geographical localisation and insecticide resistance. This
raises the possibility that symbionts may play a role in the adaptation to environmental changes and the
diversification of the B. tabaci species complex. Interestingly, B. tabaci biotypes differ in their capacity
to transmit plant viruses, which seems to be linked to the composition of the bacterial symbiotic
community they harbour, a hypothesis that needs further experimental evidence.
Methodology
Mate choice tests will be performed using males and females harbouring different associations of
facultative symbionts. These same lines will also be used to measure insect attraction to different plants.
Insect performance will be measured through the analysis of life history traits like survival, fecundity
and metabolic capacities (by HPLC profiling of relevant metabolites). Molecular biology techniques
will be used to determine the symbiont composition of the different insect lines.
Skills
This project implies manipulation of tiny (1mm) and fast moving insects, it thus requires a student
having a strong interest in insect biology, and who possibly already worked on small insects. The
recruited student should also show interest in behavioural ecology.
Environment
Experiments will be realised in two laboratories located at the same university site, University of Lyon
(Villeurbanne, France), the Laboratory of Biometry and Evolutionary Biology (LBBE, UMR CNRS
5558, Université Lyon1) and the Laboratory of Functional Biology, Insects and Interactions (UMR
INRA/INSA de Lyon 203 BF2I). The supervision will be done by members of these two laboratories,
who are collaborating since several years and already supervised jointly students’ projects. The team
‘Genetics and Evolution of host-parasite interactions’ of the LBBE is recognized as a world leading
group in the field of insect symbiosis, notably on the evolution of host-symbiont and symbiont-symbiont
interactions. Its work on B. tabaci includes the evaluation of the diversity and effects of symbiotic
communities. The team ‘Trophic SYMbioses’ of the BF2I lab has long-standing knowledge of
nutritionally-based symbioses in insects. The team is internationally recognized for its expertise in the
physiology and metabolism of symbiotic insects, working since several years on pea aphid / Buchnera
aphidicola symbiotic system. The two teams belong to a multidisciplinary institute where
bioinformatics, ecology, genetics and medicine are studied, providing a stimulating and rich
environment.
Supervision
Laurence Mouton (laurence.mouton@univ-lyon1.fr), Federica Calevro (federica.calevro@insa-lyon.fr)
References
Romba R., Gnankiné O., Drabo SF., Tiendrebeogo F., Henri H., Mouton L. & Vavre F. Abundance of Bemisia tabaci Gennadius
(Hemiptera: Aleyrodidae) and its parasitoids on vegetables and cassava plants in Burkina Faso (West Africa). Ecology and
Evolution. In press.
Simonet P., Gaget K., Balmand S., Ribeiro-Lopes M., Parisot N., Buhler K., Duport G., Vulsteke V., Febvay G., Heddi A.,
Charles H., Callaerts P., Calevro F. (2018). Bacteriocyte cell death in the pea aphid/Buchnera symbiotic system. Proceedings
of the National Academy of Sciences USA 2018 Feb 5. Pii: 201720237. doi: 10:10.1073/pnas.1720237115.
Simonet P., Gaget K., Parisot N., Duport G., Rey M., Febvay G., Charles H., Callaerts P., Colella S., Calevro F. (2016)
Disruption of phenylalanine hydroxylase reduces adult lifespan and fecundity, and impairs embryonic development in
parthenogenetic pea aphids. Scientific Reports 6, 34321; doi: 10.1038/srep34321.
Mouton L., Gnankiné O. Henri H., Terraz G., Ketoh G., Martin T., Fleury F. & Vavre F. (2015). Detection of genetically
isolated entities within the Mediterranean species of Bemisia tabaci: new insights into the systematics of this worldwide
pest. Pest Management Science, 71: 452-458.
Mouton L., Gnankiné O., Henri H., Terraz G., Houndeté T., Martin T., Vavre F. & Fleury F. (2013). Distribution Bemisia
tabaci biotypes (Homoptera: Aleyrodidae) and their associated symbiotic bacteria on host plants in western Africa. Insect
Conservation and Diversity, 6: 411-421.
Rabatel A., Febvay G., Gaget K., Duport G., Baa-Puyoulet P., Sapountzis P., Bendridi N., Rey M., Rahbé Y., Charles H.,
Calevro F., Colella S. (2013) Tyrosine pathway regulation is host-mediated in the pea aphid symbiosis during late embryonic
and early larval development. BMC Genomics 14(1):235.