Analyses of symbiotic bacterial communities in the plant pest Bemisia tabaci reveal high prevalence of Candidatus Hemipteriphilus asiaticus on the African continent

---

Résumé

Microbial symbionts are widespread in insects and some of them have been associated to adaptive
changes. Primary symbionts (P-symbionts) have a nutritional role that allows their hosts to feed on
unbalanced diets (plant sap, wood, blood). Most of them have undergone genome reduction, but their
genomes still retain genes involved in pathways that are necessary to synthesize the nutrients that their
hosts need. However, in some P-symbionts, essential pathways are incomplete and secondary symbionts
(S-symbionts) are required to complete parts of their degenerated functions. The P-symbiont of the
phloem sap-feeder Bemisia tabaci, Candidatus Portiera aleyrodidarium, lacks genes involved in the
synthesis of vitamins, cofactors, and also of some essential amino-acids. Seven S-symbionts have been
detected in the B. tabaci species complex. Phenotypic and genomic analyses have revealed various
effects, from reproductive manipulation to fitness benefits, notably some of them have complementary
metabolic capabilities to Candidatus Portiera aleyrodidarium, suggesting that their presence may be
obligatory. In order to get the full picture of the symbiotic community of this pest, we investigated,
through metabarcoding approaches, the symbiont content of individuals from Burkina Faso, a West
African country where B. tabaci induces severe crop damage. While no new putative B. tabaci S-symbiont
was identified, Candidatus Hemipteriphilus asiaticus, a symbiont only described in B. tabaci populations
from Asia, was detected for the first time on this continent. Phylogenetic analyses however reveal that it
is a different strain than the reference found in Asia. Specific diagnostic PCRs showed a high prevalence
of these S-symbionts and especially of Candidatus Hemipteriphilus asiaticus in different genetic groups.
These results suggest that Candidatus Hemipteriphilus asiaticus may affect the biology of B. tabaci and
provide fitness advantage in some B. tabaci populations.

Mots-clés

Bemisia tabaci, Candidatus Hemipteriphilus asiaticus, secondary symbionts