Seasonal genetic structure in Beijing populations of the grain aphid Sitobion miscanthi (Takahashi): an investigation using microsatellites

Abstract

The grain aphid Sitobion miscanthi (Takahashi) is a major pest of cereal crops in China. Sexual reproduction is rarely found in this species, and the reproductive strategy is expected to be reflected in the population genetic structure. Using five microsatellites, we analyzed four populations of S. miscanthi sampled during the 2005-2006 wheat season (from October to May) from a Beijing suburb. Substantial allelic diversity was found, with an average 9.8 alleles per locus, but there were only 45 five-locus genotypes detected among the 143 aphid samples. Of the six commonest fivelocus genotypes, four were found in all the seasonal populations, and must have reproduced by continuous parthenogenesis through the seasons (including a winter) because of the big differences between their observed and expected frequencies. All populations showed extremely high heterozygosity and heterozygosity excesses, and significantly deviated from Hardy-Weinberg equilibrium even in data sets including one individual per genotype. Those genetic features occur because S. miscanthi is almost anholocyclic. The population collected immediately after the winter significantly differentiated from the other three populations collected earlier or later (F ST ϭ0.059-0.064), while differentiations among the other three populations were not significant (F ST ϭϪ0.016-Ϫ0.004). The probable causes of this seasonal variation were discussed.

Genetic diversity and insecticide resistance during the growing season in the green peach aphid (Hemiptera: Aphididae) on primary and secondary hosts: a farm-scale study in Central Chile

“…and secondary ( Glycine max ) hosts. Other studies with anholocyclic aphid species such as Sitobion miscanthi and Tuberculatus quercicola have described a lack of differentiation within the season (Wang et al , 2008; Yao & Akimoto, 2009).…”

“…and secondary (Glycine max) hosts. Other studies with anholocyclic aphid species such as Sitobion miscanthi and Tuberculatus quercicola have described a lack of differentiation within the season (Wang et al, 2008;Yao & Akimoto, 2009). In the sweet-pepper field, only the samples of M. persicae collected early in the season exhibited a higher genotypic diversity than those from its associated weeds, which afterward was generally low (fig.…”

Morphometric studies of the genusSitobionMordvilko 1914 in Australia (Hemiptera: Aphididae)

“…Those with re‐arranged karyotypes (Clones 61 and 34) share allele sizes at many loci with Asian specimens of S. miscanthi (Taiwan, see Wilson et al . 1999; Beijing area, Wang et al . 2008) and their identity as S. miscanthi is unequivocal.…”

“…Because of the small number of genotypes present in Australia and New Zealand, the range of morphometric variation within Australasia may be limited regardless of the number of samples measured, although the species is much more genotypically variable in Asia (Wilson et al . 1999; Wang et al . 2008).…”

Rapid genetic turnover in populations of the insect pestBemisia tabaciMiddle East: Asia Minor 1 in an agricultural landscape

“…De Barro et al (1995b) and Vorburger (2006) found evidence of host races exhibiting high genetic structuring at the beginning of a growing season, and this genetic structuring diminished as the season progressed. Aphid populations collected immediately after winter exhibited seasonal change in genetic structure when compared to populations sampled before or after (Wang et al, 2008). Sunnucks et al (1997) reported that aphids exhibited rapid temporal genetic changes and low variation in population structure between sample sites (indicative of movement and population mixing), and Han & Caprio (2004) reported temporal genetic change in Helicoverpa virescens.…”