CONFIRMATION OF ASIAN COCKROACH BLATELLA ASAHINAI (BLATTODEA: BLATTELIDAE) INTRODUCTION TO TEXAS BASED ON GENETICS, MORPHOLOGY, AND BEHAVIOR

Abstract

Thought to be native to Japan based on the original description of specimens collected from Okinawa, Japan (Brenner et al. 1988), the Asian cockroach Blattella asahinai Mizukubo is now found in several southeastern states. Among these are Florida, portions of southern Georgia, southwestern Alabama, and Charleston County, South Carolina (Hu et al. 2005). The potential for the spread of this species to other southern U.S. States has been proposed (Atkinson et al. 1991). Interstate highways are now proving to provide major introduction routes throughout the southeast U.S. (E. Snoddy, pers. comm.). While populations of the Asian Cockroach have been proposed to occur in western Harris County, Texas (Tucker 2006) there has been no confirmation of this in literature nor have any samples been submitted for confirmation to Texas AM Roth 1986). Because of their overall similarity, original populations were thought to be German cockroaches Blattella germanica (L.). Likewise, another congener of Asian origin, the field cockroach Blattella vega Hebard is sometimes confused with B. asahinai and B. germanica. When the ability to observe these species in nature is eliminated, it can be difficult to discern them from preserved specimens, and identification has been based on cuticular hydrocarbon methods (Carlson & Brenner 1988) and molecular diagnostics (Pachamuthu et al. 2000). Herei , we apply ethological, morphological, and genetic approaches to confirm the presence of B. asahinai in Harris County, Texas. Field collected samples were preserved in 100% ethanol and voucher specimens were deposited at the Center for Urban & Structural Entomology at Texas A&M University. Geographic p sitions were recorded for samples subjected to DNA analysis with a Garmin Vista C GPS unit (Garmin International, Inc., Olathe, Kansas). Coordinates for both locations in Hunter's Creek Village were 29'46'11.06N, 95028'21.22W near Point Broad Oaks Circle, and 29046'01.12N, 95'28'00.82W near Bayou Timber. Additional sites have been found west of these locations and more are being evaluated at the present time. Morphological and ethological identification through comparisons of B. asahinai with other Blattella congeners was evaluated in accordance with Lawless (1999), Brenner et al. (1988), Ross & Mullins (1988), and Richman (2000). Extraction and purification of genomic DNA was performed with Qiagen DNEasy tissue kits (Qiagen, Inc., Valencia, CA) according to manufacturers' recommendations. PCR amplification of the nuclear rRNA ITS1 region was performed following Szalanski & Owens (2003) by using the primers rDNA2 (5'-TTGATTACGTCCCTGCCCTTT-3') described by Vrain et al. (1992), and primer rDNA1.58s (5'-GCCACCTAGTGAGCCGAGCA3') by Cherry et al. (1997). These primers amplify a 3' portion of the 18S gene, the entire ITS1 region, and a 5' section of the 5.8S gene. The ITS1 PCR protocol was 40 cycles at 94oC for 45 s, 54?C for 45 s and 72'C for 60 s. Amplified DNA from individual cockroaches was purified and concentrated with minicolumns according to the manufacturers instructions (Wizard PCRpreps, Promega, Madison, WI). Samples were sent to the University of Arkansas Medical School DNA Sequencing Facility, Little Rock, AR, for direct sequencing in both directions. Consensus sequences