Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/3/2012
Publication Date: N/A
Citation: N/A Interpretive Summary: The tarnished plant bug and a few of its close relatives comprise of cluster of very similar appearing pest species in North America. Hosts include cotton, strawberries, seed alfalfa, sunflowers, and many more crops. DNA barcoding is being used to more clearly define the pest species.
Technical Abstract: The genus Lygus (Hemiptera: Miridae) is an important group of insects that contains 43 known species worldwide. Some species within this genus are important agricultural pests in North America. Annual economic impacts in cotton, Gossypium hirsutum L., from Lygus spp. due to yield losses and control costs were estimated to exceed $100 million in recent years. The correct taxonomic identification between various Lygus species is difficult and based mainly on external morphological characters. The phenotypic diversity within a single species of this genus is not well understood, largely because few discrete morphological characters those have been identified for these species. The reliable and accurate identification between species of this genus has remained problematic due to over-lapping morphological characters. The use of mitochondrial DNA (mtDNA) Cytochrome Oxidase I (cox1) and Cytochrome Oxidase II (cox2) genes in species identification have gained popularity in recent years, with its effectiveness in identifying cryptic and new species demonstrated in insects, birds, fish and other animals. The rate of evolution in these genes is also sufficiently rapid to allow the discrimination at the species level and the identification of cryptic species and have also been used in establishing host plant associated genetic differentiation. Therefore, in this study we have attempted to develop the DNA barcode of eight species (L. lineolaris, L. plagiatus Uhler, L. rugulipennis Poppius, and L. vanduzee Knight, L. elisus Van Duzee, L. hesperus Knight, L. borealis Kelton, L. keltoni Schwartz and Foottit, and L. solidaginis (Kelton)) of genus Lygus using mitochondrial genes i.e., cox1 and cox2, respectively. The 658-bp mitochondrial barcode region (cox1) and a 768-bp region overlapping cox1 and cox2 were sequenced for all these species, which were collected from multiple sites in North America and Europe. The 768-bp cox1-cox2 nucleotide sequence codes for two partial amino acid peptides. The cox1 (1-355 bp) and cox2 (417-768 bp) sequences with intervening t-RNA (351-416 bp) are A+T rich (73%). The mtDNA 768 nucleotides encoding for the genes have 26 nucleotide-variable sites (3.4%), and seven (0.91%) phylogenetically informative sites. The shorter cox1 barcode region contains three phylogenetically informative sites. The results from this study indicate that cox1 and cox2 are suitable barcoding genes for identification of species of Lygus.