The Distribution and Host Shifts of Cotton-Melon Aphids in Northern China

Abstract

Aphis gossypii Glover (Hemiptera: Aphididae) is a serious pest of cotton in northern China. A microsatellite analysis was used to characterize the genetic structure of A. gossypii populations from different geographic, host plant, and seasonal populations in 2014. Among 906 individuals, 507 multilocus genotypes were identified, with genotypic richness values of 0.07–1.00 for the populations. We observed moderate levels of genetic differentiation among geographic populations (FST = 0.103; 95% confidence interval: 0.065–0.145) and host plant populations (FST = 0.237; 95% confidence interval: 0.187–0.296). A Mantel test of isolation by distance revealed no significant correlations between Slatkin’s linearized FST and the natural logarithm of geographic distance. A Bayesian analysis of population genetic structures identified three clusters. An analysis of molecular variance revealed significant differences among the three clusters (F = 0.26596, P < 0.0001), among seasons (F = 0.04244, P = 0.00381), and among host populations (F = 0.12975, P = 0.0029). Thus, the A. gossypii populations in northern China exhibit considerable genotypic diversity. Additionally, our findings indicated that the 31 analyzed populations could be classified as one of three host biotypes (i.e., cotton, cucumber, and pomegranate biotypes). There were also clear seasonal effects on population genetic structure diversity among aphids collected from Anyang.

The biotypes and host shifts of cotton-melon aphids Aphis gossypii in northern China

“…Many studies have reported the existence of host-specific A. gossypii biotypes, but a lack of standardization has prevented comparisons of biotypes (Ebert and Cartwright 1997). In a previous study using SSR markers, we found that A. gossypii populations in northern China exhibited greater genotypic diversity, and the 31 populations in northern China could be classified into one of 3 biotypes according to host species (Luo et al 2016). Unlike in other places, the microsatellite loci had high diversity in northern China, making it difficult to practically use.…”

“…Bioassay of laboratory host-transfer experiments was the original method used to confirm A. gossypii biotypes (Guldemond et al 1994;Liu et al 2008;Carletto et al 2009b;Wang et al 2016). Simple sequence repeat (SSR) markers were another popular method to assess A. gossypii diversity (Vanlerberghe-Masutti et al 1999;Thomas et al 2012;Luo et al 2016). Mitochondrial gene sequence polymorphisms were also used to distinguish A. gossypii biotypes (Carletto et al 2009a;Wang et al 2016).…”

“…Those primary hosts are not only hibiscus, pomegranate, and Chinese prickly ash, but also S. japonica, which was reported for the first time in China to our knowledge. Using classification with the mitochondrial gene, pomegranate was the host of the cotton host-race, and when using SSR, the population on pomegranate was classified with populations collected on cotton (Luo et al 2016). The Chinese prickly ash (Rutaceae) is one of the most ancient cultivated economic trees in Chinese mountainous regions, and is of major agricultural importance as sources of spices and traditional medicine (Feng et al 2015).…”

“…Using A. gossypii microsatellite loci (Vanlerberghe-Masutti et al 1999), Carletto et al (2009b) found that genotypes were associated with host plants, and 5 host races including cucurbits, cotton, eggplant, potato, and chili or sweet pepper were identified at a large geographical scale. We found that 31 A. gossypii populations in northern China could be classified as 3 host biotypes (Luo et al 2016). Mitochondrial genomes have been frequently used to explore insect biotype (Frohlich et al 1999); a previous study found that there was high divergence in cytochrome b sequences between cucurbit and cotton host races of A. gossypii (Carletto et al 2009a).…”

“…Samples of wingless A. gossypii aphids were collected from cotton fields in northern China in late August 2014 at a total of 20 sites, including 6 populations in Hebei Province, 6 in Henan Province (including Anyang), and 8 in Shandong Province, as done previously reported (Luo et al 2016). Only 1 individual per plant from 8-48 cotton plants per site was collected to avoid sampling the offspring of a single female.…”