|Shatters, Robert - Bob|
Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/10/2012
Publication Date: 6/1/2012
Citation: McKenzie, C.L., Bethke, J.A., Byrne, F.J., Chamberlin, J.R., Dennehy, T.J., Dickey, A.M., Gilrein, D., Hall, P.M., Ludwig, S., Oetting, R.D., Osborne, L.S., Schmale, L., Shatters, Jr., R.G. 2012. Distribution of Bemisia tabaci (Hemiptera: Aleyrodidae) biotypes in North America following the Q invasion. Journal of Economic Entomology. 105(3):753-766. Available: http://dx.doi.org/10.1603/EC11337 Interpretive Summary: Associated with the appearance of biotype Q in the U.S. in 2004 were reports from ornamental growers of increasing problems in controlling whitefly infestations due to the increased proclivity of the Q biotype to rapidly develop insecticide resistance in comparison to the resident B biotype. As a result, there was great concern over the possibility of the development of a B-Q hybrid whitefly that would have the high insecticide resistance of the Q biotype combined with the more aggressive and invasive characteristics of the B biotype. As part of an APHIS coordinated multi-state, multi-agency and multi-institutional Q biotype task force initiative, a coordinated whole country survey was conducted across North America from Jan 2005 to Dec 2010 including the islands of Bermuda and Hawaii (big island of Hawaii and Oahu), Canada and Mexico with the primary objective to monitor the introduction of the Q biotype and distribution of all Bemisia biotypes, including B, Q and New World. Our findings showed: 1) The New World biotype was detected in Texas which represents the first report of the New World biotype in the U.S. since its rapid displacement in the late 1980s by biotype B; 2) Biotype Q was detected in 23 U.S. states, Mexico and the first reports of biotype Q in Canada and Bermuda; 3) The Q biotype was found in protected commercial horticultural greenhouse plantings of forty-five percent of all ornamentals and herbs and a single tomato transplant collection, but never in open field agriculture; 4) Genetic markers identified three populations of biotype Q whiteflies, supporting the inference of independent invasions from at least three different sources; 5) Although detected as very rare occurrences, B-Q hybrids did occur but showed no evidence of persistence; and 6) Our results suggest that, unlike other countries where the Q biotype has invaded field crops, in the U.S. rapid detection and implementation of improved control strategies targeting the Q biotype has prevented the establishment of this pest beyond greenhouse production.
Technical Abstract: After the 2004 discovery of the Bemisia tabaci (Gennadius) Q biotype in the U.S., there was a vital need to determine its distribution and its interaction with the resident B biotype because of its innate ability to rapidly develop high level insecticide resistance that does not revert back to susceptibility in the absence of exposure. As part of a coordinated country-wide effort, an extensive survey of B. tabaci biotypes was conducted in North America, with the cooperation of growers, industry, state, and federal agencies, to monitor the introduction and distribution of the Q biotype. The biotype status of submitted B. tabaci samples was determined by PCR amplification and sequencing of a mitochondrial cytochrome oxidase I small subunit (mtCOI) gene fragment, characterization of two biotype discriminating microsatellite markers and esterase zymogram analysis. Two hundred and eighty collections were sampled from the U.S., Bermuda, Canada and Mexico during the period of Jan 2005 through Dec 2010. Host plants were split between ornamental and herb (67 percent) and vegetable and field (33 percent) commodities. Five collections from tomato in Mexico (2) and Texas (3) were 100 percent New World biotype. To our knowledge this is the first report of the New World biotype in the United States since its rapid displacement in the late 1980s after the introduction of biotype B. Seventy-one percent of all collections contained at least one biotype B individual and 53 percent of all collections contained only biotype B whiteflies. In this report, biotype Q was detected in 23 states in the U. S., Canada (British Columbia and Ontario territories), Bermuda, and Mexico. Forty-five percent of all collections were found to contain biotype Q in samples from ornamentals, herbs and a single collection from tomato transplants located in protected commercial horticultural greenhouses with no Q detections in open agriculture (field crops). Ten of the 15 collections (67 percent) from Canada and a single collection from Bermuda contained biotype Q which represents the first report of biotype Q for both countries. Three populations of B. tabaci biotype Q whiteflies were detected in North America which differentiated from one another at both mitochondrial and nuclear loci. Our data is consistent with the inference of independent invasions from at least three different locations. Of the 4,849 individuals analyzed from 468 collections which include data from McKenzie et al. 2009, only 16 individuals contained genetic/zymogram signatures that suggested possible hybridization of the Q and B biotypes and there was no evidence that rare hybrid B-Q marker co-occurrences persisted in any populations.