Data from: Variable resistance to spinetoram in populations of Thrips palmi across a small area unconnected to genetic similarity
Data files
Apr 30, 2020 version files 162.54 KB
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tp_22ssr_4populations_field_lab.genepop
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tp_22ssr_7populations_from_Shouguang.genepop
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tp_cox1_4haps.fas
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tp_cox1_7populations.fas
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tp_cox1-4populations.fas
Abstract
The melon thrips, Thrips palmi, is an increasingly important pest of vegetables in northern China. Some populations have developed resistance in the field to the insecticide spinetoram. Understanding the origin and dispersal of insecticide-resistant populations can shed light on resistance management strategies. In this study, we tested susceptibility of seven greenhouse populations of T. palmi to spinetoram collected from a small area of about 300 km2 in Shandong province, and examined population genetic structure across the area based on a segment of mitochondrial cox1 gene and 22 microsatellite loci to infer the possible origin and dispersal of insecticide resistance. Levels of resistance to spinetoram differed among seven populations, which included one population with high resistance (LC50 = 759.34 mg/L), three populations with medium resistance (LC50 ranged from 28.69 to 34.79 mg/L) and three populations with low resistance (LC50 ranged from 7.61 to 8.97 mg/L). The populations were genetically differentiated into two groups unrelated to both levels of resistance and geographic distance. The molecular data indicated high levels of gene flow between populations with different levels of resistance to spinetoram and low gene flow among populations with the same level of resistance, pointing to a likely separate history of resistance evolution. Resistance levels of two tested populations to spinetoram decreased 23 and 4.6 times after five generations without any exposure to the pesticide. We therefore suspect that resistance of T. palmi most likely evolved in response to local applications of the insecticide. Our study suggests that the development of resistance could be avoided or resistance even reversed by reducing usage of spinetoram.
Methods
Total DNA was extracted from individual specimens using DNeasy Blood and Tissue Kit (Qiagen, Germany). For nuclear markers, we used 22 microsatellite loci developed in a previous study (Gao, Gong, Ma, et al., 2019). A fluorescence‐labeled PC‐tail (5′ CAGGACCAGGCTACCGTG 3′) was used to label the PCR products (Schuelke, 2000; Blacket et al., 2012). Conditions for PCR amplification were described in Gao, Gong, Ma, et al. (2019). The size of amplified PCR products was determined using an ABI 3730xl DNA Analyzer with GeneScan 500 LIZ size standards. Alleles were identified with GENEMAPPER version 4.0 (Applied Biosystems, USA).
For the mitochondrial gene, a segment of cytochrome c oxidase subunit I (cox1) was amplified with primer pairs TP-AF (5′ TTTCGTCTAACCATAAAGATATCGG 3′) and TP-AR (5′TAAACTTCTGGGTGCCCAAAAAATCA 3′) (Cao et al., 2019). Polymerase chain reaction (PCR) was conducted with the following program: an initial denaturation for 3 min at 94 °C, followed by 35 cycles of 10 s at 94 °C, 15 s at 52 °C and 1 min at 68 °C, and a subsequent final extension for 10 min at 68 °C. Amplified products were purified and sequenced directly from both strands using an ABI 3730xl DNA Analyzer by Tsingke Biotechnology Co. Ltd (Beijing, China).
Usage notes
Microsatellite data (genepop format) and mitochondrial cox1 gene sequences (fasta format) for populations of Thrips palmi.
tp_22ssr_4populations_field_lab.genepop, microsatellite data for two field populations and two laboratory populations;
tp_22ssr_7populations from Shouguang.genepop, microsatellite data for seven field populations collected from Shouguang, Shandong province, China;
tp_cox1_4haps.fas, cox1 haplotypes;
tp_cox1_7populations.fas