Molecular variation of the cytochrome b DNA and protein sequences in Phytoseiulus macropilis and P. persimilis (Acari: Phytoseiidae) reflect population differentiation

Abstract

Several phytoseiid mite species are important natural enemies used in biological control strategies. In the present study, Cytb mtDNA sequences of various populations of two species, Phytoseiulus macropolis and P. persimilis, were compared to determine whether the specimens collected in Brazil could belong to P. persimilis as this latter species is reported in South America but not in Brazil. The Cytb marker was used because of its high evolution rate, assumed to capture intraspecific variation. No overlap between intra-and interspecific distances was observed but the distances were quite low for interspecific variation. This can be due to the particular biology of Phytoseiulus species and this shows the difficulty to apply a universal threshold in genetic distances to conclude about the existence of one or several species. Cytb mtDNA sequences were also considered to assess intraspecific variation. The DNA sequences of P. persimilis populations were very similar, probably because they all originated from the West Palearctic region or because of a prevalence of commercialized specimens in natura. For P. macropilis, higher genetic distances were observed and differentiation was noted according to geographic location and, to a smaller extent, pyrethroid resistance. To determine how DNA variation might impact the protein function (CytB fragment considered), the amino acid compositions of the populations studied were compared. No diagnostic mutation was observed between pyrethroid resistant and susceptible populations, whereas four mutations were identified between populations of P. macropilis separated by 1300 km (different climatic conditions). The impact of such mutations is discussed but knowledge is scarce, which makes it difficult to root testable hypotheses. The protein analysis clearly opens new perspectives in Phytoseiidae studies.

Genetic diversity of the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) with an overview of its distribution and implications for biological control

“…These markers were chosen because previous studies proved their variability at intraspecific level in Phytoseiidae species (Dos Santos and Tixier, 2017;Tixier et al, 2010aTixier et al, , 2021Queiroz et al, 2021). DNA extractions were carried out on single female specimens, following the protocol accurately described in Kanouh et al (2010) and using the Qiagen modified process.…”

“…swirskii from Cape Verde, as previous studies suggested some link between genetic differences and biological features, e.g. climate adaptation (for COI and Cytb mtDNA) and prey adaptation (for 12S rRNA) (Tixier et al, 2010a(Tixier et al, , 2021Queiroz et al, 2021). Even if these markers are usually considered neutral, some studies have shown that mutations can be associated to abiotic factors (pesticide resistance in Tetranychus urticae (Koch) (Van Nieuwenhuyse et al, 2009;Fotoukkiaii et al, 2020), temperature adaptation in anchovies and Lottia in COI mtDNA sequences (Dong et al, 2009;Silva et al 2014)).…”

“…Recent studies exploring possible relationships between genetic differentiation and biological features, show slight differences in populations of Typhlodromus (Anthoseius) recki Wainstein and Phytoseiulus longipes Evans (using 12S rRNA sequences) potentially associated with feeding habits (Tixier et al, 2010a;Tixier et al, 2021). Likewise, differences in amino acid sequences of the mitochondrial Cytb sequence in several species of Phytoseiidae mites seem to be associated with adaptation to climatic conditions (Queiroz et al, 2021;Tixier et al, 2021).…”