What Is the Spatial Extent of a Bemisia tabaci Population?
Round 1
Reviewer 1 Report
The authors ask about the spatial extent of the genetic variation in one of the economically important insect species, Bemisia tabaci. They synthesized the literature on B. tabaci population genetics and described trends seen in analyses of mitochondrial and nuclear markers. I agree that the research question is current and interesting. Studies like this are of broad interest as B. tabaci is one of the agricultural pests worldwide. I recommend the submitted manuscript for publication. I have only one remark that I believe will help to improve the overall presentation of the manuscript. In the chapter focused on cytochrome oxidase I, the authors emphasize that a single COI haplotype can be found across entire regions. Could it be connected with the high prevalence of Wolbachia in this species? Like mitochondria, Wolbachia is inherited from mother to offspring, causing potential associations between mitochondrial DNA and endosymbiont’s strain. Please, consider adding an additional paragraph reporting this question.
Author Response
The reviewer brings up a great point. In response, we have added the following text to the COI section (lines 115-117): “In addition, asymmetric gene flow due to cytoplasmic-incompatibility caused by Wolbachia can constrain gene flow among uninfected and infected B. tabaci lineages, further limiting recovery of genetic diversity among invasive populations [67,74].”
Reviewer 2 Report
This manuscript is a very comprehensive review addressing the question of genetic structure of Bemisia tabacipopulations and their spatial extent. The authors make a thorough search in the literature collecting and analyzing all the elements therein that are needed to assess the scale of connectivity and gene flow between B. tabaci populations (FST, analysis of molecular variance, isolation by distance, heterozygosity and deviations from H-W equilibrium) obtained by the use of, mostly, microsatellite markers. They also make pertinent suggestions on future research axes that will certainly contribute to better understand the ecology of B. tabaci and manage this important agricultural pest.
This work merits definitely to be published. However one element that, in my opinion is missing / not addressed in this manuscript is the role of endosymbionts in shaping the population structure (benefits and adaptation to local ecological factors), in the non random mating (heterozygote deficits, Wahlund effect,..) and in shaping the mitochondrial variability patterns observed. I think that this review would benefit by including (at least mentioning) the possible role of secondary endosymbionts in the population structure of B. tabaci.
Typos:
Line 180, write Figure 3 instead of Figure 4,
Lines 224 and 231 Figure 4 instead of Figure 2
Author Response
The reviewer brings up a great point. In response, we have added text about the possible contribution of Wolbachia to observed patterns of heterozygote deficits (lines 256-263): “Lastly, consequences of Wolbachia infection have been proposed to explain heterozygote deficits, whether due to sex-ratio distortions [68] or asymmetrical gene flow due to cytoplasmic-incompatibility [67]. Wolbachia infections can be quite common among MED and MEAM1, but also extremely rare, depending on geography [51,57,84,85]. The potential for horizontal transmission via shared host plants, in addition to vertical transmission, suggests that Wolbachia infections will only grow in importance with time [86]. However, studies examining the effect of Wolbachia infection status on B. tabaci population structure have so far found no relationship [67,68].”
