Species‐complex diversification and host‐plant associations in Bemisia tabaci: A plant‐defence, detoxification perspective revealed by RNA‐Seq analyses

Abstract

Insect-plant associations and their role in diversification are mostly studied in specialists. Here, we aimed to identify macroevolution patterns in the relationships between generalists and their host plants that have the potential to promote diversification. We focused on the Bemisia tabaci species complex containing more than 35 cryptic species. Mechanisms for explaining this impressive diversification have focused so far on allopatric forces that assume a common, broad, host range. We conducted a literature survey which indicated that species in the complex differ in their host range, with only few showing a truly broad one. We then selected six species, representing different phylogenetic groups and documented host ranges. We tested whether differences in the species expression profiles of detoxification genes are shaped more by their phylogenetic relationships or by their ability to successfully utilize multiple hosts, including novel ones. Performance assays divided the six species into two groups of three, one showing higher performance on various hosts than the other (the lower performance group). The same grouping pattern appeared when the species were clustered according to their expression profiles. Only species placed in the lower performance group showed a tendency to lower the expression of multiple genes. Taken together, these findings bring evidence for the existence of a common detoxification "machinery," shared between species that can perform well on multiple hosts. We raise the possibility that this "machinery" might have played a passive role in the diversification of the complex, by allowing successful migration to new/novel environments, leading, in some cases, to fragmentation and speciation.

Inside out: microbiota dynamics during host-plant adaptation of whiteflies

“…6). This might synergize or complement insect-specific short adaptation mechanisms to lesssuitable host plants that are well documented and largely involve metabolic adaptation by the overexpression of genes coding for detoxification enzymes and xenobiotic transporters [2,59]. Further analyses are required in order to determine the exact contribution of each component to the ability of the population to adapt relatively quickly (second to third generations) to lesssuitable host plants.…”

“…Generalist insects are extraordinary in their ability to perceive diverse olfactory and gustatory cues, digest complex nitrogen and carbon compounds, and detoxify different secondary defense metabolites [1,2]. Because in every host switch these insects are required to establish new temporal interactions and to overcome a new array of plant defenses in a short time, their adaptation to a new host is believed not to involve genotypic selection, but the production of different phenotypes with one given genotype [3].…”

Insecticide resistance and fitness cost in Bemisia tabaci (Hemiptera: Aleyrodidae) invasive and resident species in La Réunion Island

“…The second hypothesis of different intrinsic evolutionary potential would require some further biological characterization of the two species, already knowing that MEAM1 field population size is larger than IO, it has a capacity to develop under a broader range of temperatures and it is highly polyphagous . As an example, the evolution of resistance may be hindered in IO species by molecular constraints.…”

“…The second hypothesis of different intrinsic evolutionary potential would require some further biological characterization of the two species, already knowing that MEAM1 field population size is larger than IO, 31,32,36 it has a capacity to develop under a broader range of temperatures 32 and it is highly polyphagous. 60 As an example, the evolution of resistance may be hindered in IO species by molecular constraints. Such a case has been reported on other insects such as mosquitoes (Aedes aegypti), where a particular codon constraint prevented the apparition of the required mutation in the acetylcholinesterase gene to confer resistance to organophosphates and carbamates.…”

Assessing whitefly diversity to infer about begomovirus dynamics in cassava in Brazil

“…Based on molecular phylogeny of the mitochondrial cytochrome oxidase I (mtCOI) gene, it has been proposed that B. tabaci consists of a complex of more than 40 cryptic (morphologically indistinguishable) species (21)(22)(23)(24)(25). Partial or complete reproductive isolation and biological and ecological differences among distinct species within the complex support the proposed classification (18,(26)(27)(28). The global dissemination of polyphagous and invasive species, such as B. tabaci Middle East-Asia Minor 1 (BtMEAM1) and B. tabaci Mediterranean (BtMED), have caused major changes in the epidemiology of crop-infecting begomoviruses such as Tomato yellow leaf curl virus (TYLCV), currently present in all the main tomato producing areas of the world (29)(30)(31).…”