Distribution of <I>Bemisia tabaci</I> (Hemiptera: Aleyrodidae) Biotypes in North America After the Q Invasion

Abstract

After the 2004 discovery of the Bemisia tabaci (Gennadius) (Hemiptera Aleyrodidae) Q biotype in the United States, there was a vital need to determine the geographical and host distribution as well as its interaction with the resident B biotype because of its innate ability to rapidly develop high-level insecticide resistance that persists 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, local, state, and federal agencies, to monitor the introduction and distribution of the Q biotype. The biotype status of submitted B. tabaci samples was determined either by polymerase chain reaction amplification and sequencing of a mitochondrial cytochrome oxidase I small subunit gene fragment and characterization of two biotype discriminating nuclear microsatellite markers or esterase zymogram analysis. Two hundred and eighty collections were sampled from the United States, Bermuda, Canada, and Mexico during January 2005 through December 2011. Host plants were split between ornamental plant and culinary herb (67%) and vegetable and field crop (33%) commodities. The New World biotype was detected on field-grown tomatoes (Solanum lycopersicum L.) in Mexico (two) and in commercial greenhouses in Texas (three) and represented 100% of these five collections. To our knowledge, the latter identification represents 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% of all collections contained only biotype B whiteflies. Biotype Q was detected in 23 states in the United States, 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, but there were no Q detections in outdoor agriculture (vegetable or field crops). Ten of the 15 collections (67%) from Canada and a single collection from Bermuda contained biotype Q, representing the first reports of biotype Q for both countries. Three distinct mitochondrial haplotypes of B. tabaci biotype Q whiteflies were detected in North America Our data are consistent with the inference of independent invasions from at least three different locations. Of the 4,641 individuals analyzed from 517 collections that include data from our previous work, only 16 individuals contained genetic or zymogram evidence of 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.

Insecticides promote viral outbreaks by altering herbivore competition

“…In Israel, for instance, the MEAM1-MED competitive hierarchy fluctuates, with MEAM1 being relatively more abundant than MED in field crops and MED more abundant than MEAM1 in glasshouses and other protected environments where insecticides are intensively used (Kontsedalov et al 2012). A similar but more extreme situation is observed in the United States, where MED is only found in greenhouses in 23 states, while MEAM1 is present in both field crops and greenhouses (McKenzie et al 2012). Why has the MEAM1-MED interaction played out so differently in China?…”

“…Organized and sustained grower education facilitated the deployment and adoption of this plan, which has lowered both Bemisia-targeted insecticide use and whitefly problems (Ellsworth and Martinez-Carrillo 2001). The emphasis on managing for reduced insectide resistance may have favored MEAM1 in field crops in the United States, keeping MED relatively rare and confined to highpesticide areas like greenhouses (McKenzie et al 2012). These disparate approaches to pest management likely explain why TYLCV has become a greater problem in China than in the United States.…”

Demographic Trends in Mixed <I>Bemisia tabaci</I> (Hemiptera: Aleyrodidae) Cryptic Species Populations in Commercial Poinsettia Under Biological Control- and Insecticide-Based Management

“…It is now widely recognized that B. tabaci is a cryptic species complex consisting of at least 24 morphologically indistinguishable yet behaviorally and physiologically distinct species (Boykin et al 2007, Dinsdale et al 2010, De Barro et al 2011, Liu et al 2012, McKenzie et al 2012, Tay et al 2012). To account for this variation, a convention of assigning a unique "biotype" designation to distinct B. tabaci populations was adopted, of which 36 biotypes are reported in the literature (De Barro et al 2011).…”

“…For the purposes of this manuscript, we follow this phylogeographic naming convention. Of the 24 putative cryptic species, Mediterranean (formerly "biotype Q," or sweet potato whiteßy) and Middle East-Asia Minor 1 (MEAM1: formerly "biotype B," or Bemisia argentifolii Bellows & Perring, silver leaf whiteßy) are the most commonly encountered in the pest management literature (Liu et al 2007, McKenzie et al 2012) and often infest ornamental crops in North America, including poinsettia. Both of these species have experienced significant range expansions as a result of international trade (Cheek andMacdonald 1994, Dalton 2006).…”

“…Both of these species have experienced significant range expansions as a result of international trade (Cheek andMacdonald 1994, Dalton 2006). A third cryptic species, New World (formerly, "biotype A, C, D, F, Jatropha, N, R, Sida"), is present in North America, but it rarely infests crop plants and is generally not considered economically signiÞcant (Dinsdale et al 2010, McKenzie et al 2012. Of practical importance is the fact that Mediterranean is more resistant to, and likely has a greater capacity to develop resistance to, various insecticides than other B. tabaci cryptic species, in particular MEAM1 (Dennehy et al 2010, Li et al 2012.…”