Bemisia tabaci has long been considered a complex species. It rose to global prominence in the 1980s owing to the global invasion by the commonly named B biotype. Since then, the concomitant eruption of a group of plant viruses known as begomoviruses has created considerable management problems in many countries. However, an enduring set of questions remains: Is B. tabaci a complex species or a species complex, what are Bemisia biotypes, and how did all the genetic variability arise? This review considers these issues and concludes that there is now sufficient evidence to state that B. tabaci is not made up of biotypes and that the use of biotype in this context is erroneous and misleading. Instead, B. tabaci is a complex of 11 well-defined high-level groups containing at least 24 morphologically indistinguishable species.

Bemisia tabaci: A Statement of Species Status

The global status of insect resistance to neonicotinoid insecticides

Identifying species boundaries within morphologically indistinguishable cryptic species complexes is often contentious. For the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodoidea: Aleyrodidae), the lack of a clear understanding about the genetic limits of the numerous genetic groups and biotypes so far identified has resulted in a lack of consistency in the application of the terms, the approaches use to apply them and in our understanding of what genetic structure within B. tabaci means. Our response has been to use mitochondrial gene cytochrome oxidase one to consider how to clearly and consistently define genetic separation. Using Bayesian phylogenetic analysis and analysis of sequence pairwise divergence we found a considerably higher to number of genetic groups than had been previously determined with two breaks in the distribution, one at 11% and another at 3.5%. At >11% divergence, 11 distinct groups were resolved, whereas at >3.5% divergence 24 groups were identified. Consensus sequences for each of these groups were determined and were shown to be useful in the correct assignment of sequences of unknown origin. The 3.5% divergence bound is consistent with species level separations in other insect taxa and Suggests that B. tabaci is it cryptic species composed of at least 24 distinct species. We further show that the placement of Bemesia atriplex (Froggatt) within the B. tabaci in, group adds further weight to the argument for species level separation within B. tabaci. This new analysis, which constructs consensus sequences and uses these its a standard against which unknown sequences call be compared, provides for the first time it consistent means of identifying the genetic hounds of each species with it high degree of certainty.

Refined global analysis of Bemisia tabaci (Hemiptera: Sternorrhyncha: Aleyrodoidea: Aleyrodidae) mitochondrial cytochrome oxidase 1 to identify species level genetic boundaries.

During the establishment phase of a biological invasion, population dynamics are strongly influenced by Allee effects and stochastic dynamics, both of which may lead to extinction of low-density populations. Allee effects refer to a decline in population growth rate with a decline in abundance and can arise from various mechanisms. Strategies to eradicate newly established populations should focus on either enhancing Allee effects or suppressing populations below Allee thresholds, such that extinction proceeds without further intervention. The spread phase of invasions results from the coupling of population growth with dispersal. Reaction-diffusion is the simplest form of spread, resulting in continuous expansion and asymptotically constant radial rates of spread. However, spread of most nonindigenous insects is characterized by occasional long-distance dispersal, which results in the formation of isolated colonies that grow, coalesce, and greatly increase spread. Allee effects also affect spread, generally in a negative fashion. Efforts to slow, stop, or reverse spread should incorporate the spread dynamics unique to the target species.

https://www.nrs.fs.fed.us/pubs/jrnl/2008/nrs_2008_liebhold_001.pdf

Population ecology of insect invasions and their management

Insecticidal control and resistance management for Bemisia tabaci

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1357&context=usdaarsfacpub

Mrv Oliveira

Papers

History, current status and collaborative research projects for Bemisia tabaci