Fluorescence in situ hybridization analysis of endosymbiont genera reveals novel infection patterns in a tomato-infesting Bemisia tabaci population from Brazil

Abstract

The Bemisia tabaci cryptic species complex harbors a diversified flora of primary and secondary endosymbionts, which plays crucial roles in many aspects of the insect biology. The endosymbiont infection pattern is dependent upon many factors, including host plant and geographic origin. In Brazil, the invasion of B. tabaci Middle East-Asia Minor-1 (MEAM 1) populations was observed in tomato (Solanum lycopersicum L.) fields in the 1990s, which was followed by severe begomovirus epidemics. Here we confirmed the vertical transmission of "Candidatus Portiera" and the localization of secondary endosymbionts in distinct B. tabaci developmental stages. Hamiltonella defensa was detected in bacteriocytes but also scattered in the leg muscles as well as in the male heads. Wolbachia-specific signals were found in eggs, nymphs, male adults, and female gonads in predominant association with bacteriocytes. These results were somewhat surprising since Wolbachia infection is rarely found in MEAM 1 populations from the Old World. Our results reinforce the notion that endosymbiont infection pattern may vary according to the insect population, gender, developmental stage, and geographic origin. This characterization will provide tools to study the endosymbiont function in the transmission ability/efficiency of a complex of tomato-infecting bipartite begomoviruses by B. tabaci under Neotropical conditions.

Whitefly endosymbionts: IPM opportunity or tilting at windmills?

“…Bacteriocyte confinement and low genetic diversity are indicative of very tight association with its host and absence of horizontal transmission. In contrast, Blawid et al ( 2015 ) reported apparent localization of Hamiltonella in mouthparts, reproductive organs, and leg muscle in B. tabaci MEAM1. More studies are needed to confirm this phenotype with certainty as single detection in combination with visible cuticle autofluorescence and absence of data on which percentage of individuals showed this signal cast a doubt on the validity of this detection.…”

“…nr furuhashii for 48 h after its contact with Wolbachia-infected whiteflies (Li et al 2017a ; Ahmed et al 2015 ). Within whitefly populations, Wolbachia is primarily maternally inherited, and horizontal transmission, while certainly possible, is a secondary method (Kanakala and Ghanim 2019 ; Shi et al 2016 ; Blawid et al 2015 ). Presence of multiple groups and evidence of recent horizontal transfers hint at the possibility of whiteflies to be infected with Wolbachia strains that are not naturally found in whiteflies, potentially including pathogenic strains (Kanakala and Ghanim 2019 ).…”

Population Dynamics of Whiteflies and Associated Viruses in South America: Research Progress and Perspectives

“…The endosymbionts are also evolving according to the whitefly species. A survey among MEAM1 populations collected between 2010-2017 in Brazil showed that they harbor the secondary endosymbionts Hamiltonella, Rickettsia, Cardinium, Wolbachia, and Fritschea, but with a predominance of Hamiltonella and Rickettsia [14,35,80]. A MEAM1 population from Uruguay showed co-infection with Rickettsia, Wolbachia, and Cardinium [19].…”

Effects of a presumably protective endosymbiont on life‐history characters and their plasticity for its host aphid on three plants

“…Indeed, research on the cowpea aphid ( Aphis craccivora ) shows that H. defensa can be found only in aphid individuals collected from alfalfa, which indicates its infection may be in the benefit of the host aphid in dealing with variable selection pressures on host plants (Brady & White, ). Additional evidence of H. defensa 's potential roles in insect‐plant interactions includes: (a) clones of A. pisum harboring H. defensa are much better suited to survive on alfalfa ( Medicago sativa ), while those carrying R. insecticola perform better on clover ( Trifolium repens ; Leonardo & Muiru, ); (b) the infection of H. defensa has been found to be associated with populations of Bemisia tabaci (Gennadius) from the MEAM 1 (Middle East‐ Asia Minor 1) group only (Blawid et al, ); and (c) most individuals of aphids collected from plants of Genista sp. harbor a combination of H. defensa and Serratia symbiotica (Peccoud, Maheo, Huerta, Laurence, & Simon, ).…”