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

Abstract

Microbial symbionts are widespread in insects and some of them have been associated with 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.

Spatio-temporal changes in endosymbiont diversity and composition in the African cassava whitefly, Bemisia tabaci SSA1

“…This is to show that if there are multiple genetic variants within the population, we might predict that the presence/absence and relative abundance of different haplotypes would show variation among whitefly samples harbouring a particular species of the endosymbiont. Similarly, three strains of Hemipteriphilus were detected in one study on MED Q1 and MED Q3 and ASL whiteflies using three genes including 16S rRNA gene (483 bp), GroEL (269 bp) and GltA (190 bp;Mouton et al, 2022).…”

“…Here, we found that Hemipteriphilus sequences were clustered with one strain of Rickettsia. Another study in Burkina Faso also identified Hemipteriphilus similar to Rickettsia using 16S rRNA gene in Illumina sequencing technology in MED-Q1, MED-Q3 and ASL genetic groups (Mouton et al, 2022). The sequences of Hemipteriphilus and Rickettsia are so similar that they are difficult to differentiate especially using 16S rRNA primers.…”

Subcellular Niche Segregation of Co-Obligate Symbionts in Whiteflies

“…Arsenophonus might establish co-obligate symbiotic systems with Portiera in Asia II 6 as well as in T. vaporariorum . In many geographic regions, Hamiltonella and Arsenophonus are rarely found in the same individual of B. tabaci and T. vaporariorum ( 16 – 23 , 67 ), suggesting that the two symbiotic bacteria are competing over functional and cytological niches. Moreover, it appears that the habitat segregation system was established in a common ancestor of species in Aleyrodinae and was conserved, while the bacterial partners coexisting with Portiera have been replaced ( Fig.…”

Sidestepping Darwin: horizontal gene transfer from plants to insects

“…That most foreign genes so far reported in eukaryotes are from prokaryotes (this is especially true for insects [31,66]) may in part be due to the capacity of several bacteria to transfer their DNA to eukaryotic cells through conjugation [67]. Furthermore, many arthropod and other metazoan species harbor obligate or facultative intracellular symbionts [68], some of which are in close contact with the host germline genome, facilitating HT [30]. The higher proportion of foreign prokaryotic versus eukaryotic genes so far 9 uncovered in eukaryote genomes may also have methodological underpinnings.…”