The whitefly Bemisia tabaci is a closely related group of
> 35 cryptic species that feed on the phloem sap of a broad
range of host plants. Species in the complex differ in their host-range
breadth, but the mechanisms involved remain poorly understood. We
investigated, therefore, how six different B. tabaci species cope
with the environmental unpredictability presented by a set of four
common and novel host plants. Behavioural studies indicated large
differences in performances on the four hosts and putative
specialization of one of the species to cassava plants. Transcriptomic
analyses revealed two main insights. First, a large set of genes
involved in metabolism (> 85%) showed differences in
expression between the six species, and each species could be
characterized by its own unique expression pattern of metabolic genes.
However, within species, these genes were constitutively expressed, with
a low level of environmental responsiveness (i.e., to host change).
Second, within each species, sets of genes mainly associated with the
super-pathways “environmental information processing” and “organismal
systems”, responded to the host switching events. These included genes
encoding for proteins involved in sugar homeostasis, signal
transduction, membrane transport and immune, endocrine, sensory and
digestive responses. Our findings suggested that the six B.
tabaci species can be divided into four performance/transcriptomic
“Types” and that polyphagy can be achieved in multiple ways. However,
polyphagy level is determined by the specific identity of the metabolic
genes/pathways that are enriched and overexpressed in each species (the
species’ individual metabolic “tool kit”).