Evidence of a high level of gene flow among apple trees in Tetranychus urticae

Abstract

The dispersal mechanism of the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) could affect predator-prey population dynamics and the spread of acaricide resistance. To investigate the propensity for spider mite migration in the field, the genetic structure of spider mite populations was studied in two apple orchards using five microsatellite markers. Adult female mites were collected from trees separated by approximately 10-24 m along a line covering a distance of about 100 m. The genetic data suggested that a high population density increased the migration rate among the breeding colonies within a single tree. Spatial autocorrelation analysis suggested a positive genetic structure in the first distance class within the two orchards, which might have been caused by crawling or short-distance aerial dispersal. Meanwhile, mites may also have a large-scale migration system that could cause a high level of gene flow and constrained isolation-by-distance or genetic clines within the approximately 100-m range of the study sites. Therefore, mites might aerially disperse over long distances on a scale of <100 m while also taking shorter trips among nearby trees within a distance of 10-24 m in the apple orchards.

Population structure of the predatory mite Neoseiulus womersleyi in a tea field based on an analysis of microsatellite DNA markers

“…Fine-scale analysis of the population structure using microsatellite markers has been conducted in some species of spider mites (Navajas et al 2002; Nishimura et al 2005; Uesugi et al 2009a, b). Uesugi et al (2009b) demonstrated frequent gene flow within field populations of spider mites.…”

“…Uesugi et al (2009b) demonstrated frequent gene flow within field populations of spider mites. Our study suggested that populations of phytoseiid mites were stable in the evergreen tea fields.…”

Microsatellites reveal a strong subdivision of genetic structure in Chinese populations of the mite Tetranychus urticae Koch (Acari: Tetranychidae)

“…The frequency of null alleles in microsatellite loci seems to be greater in T. urticae than in insects [16], probably because of a high rate of mutation in the region flanking the microsatellites [17]. In previous studies of the genetic structure for T. urtica e based on microsatellites, the presence of null alleles, inbreeding due to patchy distributions, arrhenotokous mode of reproduction and a Wahlund effect caused by an inaccurate sampling method were considered to be the reasons of departure from HWE [12,15,18,19]. In this study, according to the estimate of the null allele frequencies following the EM algorithm, heterozygote deficiency caused by null allele may be the main factor contributing to the departure from HWE.…”

Isolation, characterization and PCR multiplexing of microsatellite loci for a mite crop pest, Tetranychus urticae (Acari: Tetranychidae)

“…The host plants where the mite develops seems to also have some influence. Genetic data from mites collected on citrus groves suggests some population differentiation between individuals collected on trees and weeds [8], while high level of dispersion among apple orchards tend to reduce genetic differentiation [9]. Genetic markers have also helped to further clarify taxonomic issues as the status of the red and green forms of T. urticae [6].…”

“…Among the 42 screened markers, 14 showed unambiguous genotype patterns and were kept and amplified into three PCR multiplex kits in combination with 10 primers pairs previously described [9, 4, 13] (Table 1). The three multiplex sets were tested using the amplification protocol described above.…”