A Molecular identification for economically important thrips species
Garza R, Ruiz R, Ciomperlik M
USDA, APHIS, CPHST, Pest Detection and Diagnostic Management Laboratory, 22675 N. Moorefield Rd., Edinburg, TX 78541.
Correspondence: roxanne.e.garza@aphis.usda.gov
Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) is a new invasive pest to the Caribbean, and poses a significant threat to US agriculture and trade in the western hemisphere. This pest thrips has recently invaded the Caribbean islands of St. Vincent, St. Lucia, and Trinidad (Ciomperlik MA, Seal D. 2004. USDA APHIS PPQ, Technical Report). Since 1984, USDA-APHIS inspectors at various ports of entry have reported finding live S. dorsalis a total of 89 times from imported plant materials of 48 plant taxa (USDA 2003. Port Information Network, PIN-309: quarantine status database. USDA, APHIS, PPQ). Scirtothrips dorsalis is a polyphagous pest that is widespread in habitat ranging from temperate to tropical climatic regions in Pakistan, Japan and Australia (Mound and Palmer 1981). It is a pest of economic importance in citrus growing regions of Asia, where feeding can cause significant leaf deformation, fruit damage and yield reductions. S. dorsalis is an economically important pest of chili pepper, castor, cotton, onion and other crops with physical damage that can range from stunting and wilting of young leaves and shoots to total defoliation, and potentially heavy crop loss (Ananthakrishnan 1993. Annual Review of Entomology 38: 71¨C92; CABI/EPPO 1997. Quarantine Pests for Europe, 2nd Ed). Traditional morphological identification of S. dorsalis requires slide mounting of specimens and knowledge of distinct characters visible by microscopic examination. The accurate identification of pest species is fundamental in pest management programs. Molecular based methods provide a means for the accurate identification of species. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach developed by Toda and Komazaki (2002, Bulletin of Entomological Research 92: 359¨C363) has been used to identify certain thrips species including S. dorsalis at our laboratory. In this study, PCR and DNA sequencing are being utilized to explore two regions of the mitochondrial gene, cytochrome oxidase I (COI). The DNA sequence data may provide information on the population genetic structure of S. dorsalis as well as its relationship to other thrips species. The DNA sequences will be analyzed to determine their potential for the development of species-specific molecular markers which will facilitate the design of real-time PCR assays. Real-time PCR will provide a fast and reliable method for the accurate identification of Scirtothrips dorsalis.
