Molecular Genetic Structures Of Populations In Tetranychus Urticae Koch And T. Cinnabarinus (Boisduval) (Acari: Tetranychidae) From China

Both the two-spotted spider mite Tetranychus urticae Koch and the carmine spider mite T. cinnabarinus (Boisduval), which belong to the genus Tetranychus in the Acari, Arachnida, are widely distributed in China. The former is a world-wide pest damaging many crops and fruit trees. The invasion of the two-spotted spider mite into China was first reported in 1983 in Beijing and the mite has spread into many regions in northern and northeastern China. The two-spotted spider mite has become the most important pest in apple orchards in Shandong, Liaoning and Shaanxi Provinces. The carmine spider mite is the most serious mite pest in China, which damages cotton, bean, white mulberry, cassava, melons, and greenhouse crops, causing great loss to agriculture. Owing to their rapid developments and high reproductive capacities, new geographical populations of these mites are established easily in other areas. In this study, we use molecular techniques to examine the intraspecific variation of mitochondrial COI and ribosomal ITS2 sequences among the populations of T. urticae and T. cinnabarinus collected from different geographical areas in China respectively. Additionally, we discuss the genetic structure and the molecular diversity between the two spider mites based on the two molecular markers.1. The collection and rearing of experimental materialSpecimens of T. urticae and T. cinnabarinus used in this study were collected from an extensive geographical scale in some representative regions of China. Mites were then reared in the laboratory on leaf discs of common bean (Phaseolus vulgaris L.) at 25±1℃, 60% r.h. and under L16:D8 conditions. Up to now, there have been 13 geographical populations of the two-spotted spider mites, and 27 populations of the carmine spider mites in our laboratory.2. The sequencing and comparison of COI and ITS2 fragments between different geographical populationsThe mitochondrial DNA (mtDNA) has become one of the most useful markers for understanding population structures and phylogenetic relationships of animal...