Bemisia Tabaci Species Complex Research Articles

Scientific Opinion on the pest categorisation ofTomato yellow leaf curl virusand related viruses causing tomato yellow leaf curl disease in Europe

The Panel on Plant Health performed for the European Union (EU) territory a pest categorisation of Tomato yellow leaf curl virus (TYLCV) and three related viruses, Tomato yellow leaf curl Sardinia virus (TYLCSV), Tomato yellow leaf curl Axarquia virus (TYLCAxV) and Tomato yellow leaf curl Malaga virus (TYLCMaV), which collectively cause the tomato yellow leaf curl disease (TYLCD) in Europe. The viruses are well-defined species of the genus Begomovirus, are exclusively transmitted by members of the Bemisia tabaci species complex and have tomato, as well as a few other crops or weeds, as their hosts. TYLCV is listed on tomato plants for planting, other than seeds, in Annex IIAII of Directive 2000/29/EC. While establishment and local spread rely on the Bemisia vector, the viruses can also be disseminated over long distances by movement of infected plants for planting or by consignments of non-host plants carrying viruliferous whiteflies. Establishment outdoors and spread are limited to regions with ecoclimatic conditions suitable for the establishment of vector populations in the open. Outbreaks can nevertheless occur in other regions under protected cultivation conditions. Because of the very high potential impact of TYLCD, tomato production in affected regions requires intensive crop management efforts to reduce impact. TYLCV appears to be present in almost all EU regions with suitable ecoclimatic conditions for its establishment in open fields, while the other three viruses do not appear to have reached their full establishment potential. All four viruses are absent from other regions of the EU but have the potential to cause temporary outbreaks there. © European Food Safety Authority, 2014

A practical guide to identifying members of the Bemisia tabaci species complex: and other morphologically identical species

Members of the Bemisia tabaci species complex (whiteflies) are a considerable threat to a broad range of agriculture and horticulture food and fiber crops. There are hundreds of papers a year published on the members of B. tabaci species complex, many failing to either correctly identify the species involved or confusing identity. Correct identification is a crucial first step in any study, yet all too often, especially in cases where the primary focus of the study is plant pathology, is overlooked. The whitefly research community has struggled for years with common terminology and consistent methods for species identification of various members of the complex due to 1) the lack of a reliable global genetic resource and 2) the complexities of the phylogenetic methods needed to identify unknown individuals correctly. The goal of this paper are to provide a practical guide for identifying unknown whiteflies using a global curated dataset of mitochondrial COI that is freely available at http://dx.doi.org/10.4225/08/50EB54B6F1042. The methods and resources outlined here can be readily extended to other species that are morphologically indistinguishable.

RNA viral metagenome of whiteflies leads to the discovery and characterization of a whitefly-transmitted carlavirus in North America.

Whiteflies from the Bemisia tabaci species complex have the ability to transmit a large number of plant viruses and are some of the most detrimental pests in agriculture. Although whiteflies are known to transmit both DNA and RNA viruses, most of the diversity has been recorded for the former, specifically for the Begomovirus genus. This study investigated the total diversity of DNA and RNA viruses found in whiteflies collected from a single site in Florida to evaluate if there are additional, previously undetected viral types within the B. tabaci vector. Metagenomic analysis of viral DNA extracted from the whiteflies only resulted in the detection of begomoviruses. In contrast, whiteflies contained sequences similar to RNA viruses from divergent groups, with a diversity that extends beyond currently described viruses. The metagenomic analysis of whiteflies also led to the first report of a whitefly-transmitted RNA virus similar to Cowpea mild mottle virus (CpMMV Florida) (genus Carlavirus) in North America. Further investigation resulted in the detection of CpMMV Florida in native and cultivated plants growing near the original field site of whitefly collection and determination of its experimental host range. Analysis of complete CpMMV Florida genomes recovered from whiteflies and plants suggests that the current classification criteria for carlaviruses need to be reevaluated. Overall, metagenomic analysis supports that DNA plant viruses carried by B. tabaci are dominated by begomoviruses, whereas significantly less is known about RNA viruses present in this damaging insect vector.

Sensitivity of Bemisia tabaci (Hemiptera: Aleyrodidae) to several new insecticides in China: effects of insecticide type and whitefly species, strain, and stage.

Whitefly biotypes B and Q are the two most damaging members of the Bemisia tabaci (Hemiptera: Aleyrodidae) species complex. Control of B. tabaci (and especially of Q) has been impaired by resistance to commonly used insecticides. To find new insecticides for B. tabaci management in China, we investigated the sensitivity of eggs, larvae, and adults of laboratory strains of B and Q (named Lab-B and Lab-Q) and field strains of Q to several insecticides. For eggs, larvae, and adults of B. tabaci and for six insecticides (cyantraniliprole, chlorantraniliprole, pyriproxyfen, buprofezin, acetamiprid, and thiamethoxam), LC 50 values were higher for Lab-Q than for Lab-B; avermectin LC 50 values, however, were low for adults of both Lab-Q and Lab-B. Based on the laboratory results, insecticides were selected to test against eggs, larvae, and adults of four field strains of B. tabaci Q. Although the field strains differed in their sensitivity to the insecticides, the eggs and larvae of all strains were highly sensitive to cyantraniliprole, and the adults of all strains were highly sensitive to avermectin. The eggs, larvae, and adults of B. tabaci Q were generally more resistant than those of B. tabaci B to the tested insecticides. B. tabaci Q eggs and larvae were sensitive to cyantraniliprole and pyriproxyfen, whereas B. tabaci Q adults were sensitive to avermectin. Field trials should be conducted with cyantraniliprole, pyriproxyfen, and avermectin for control of B. tabaci Q and B in China.

Molecular characterization of genetic diversity within the Africa/Middle East/Asia Minor and Sub-Saharan African groups of the Bemisia tabaci species complex

Bemisia tabaci Gennadius is a major plant pest in many agricultural systems worldwide. It is a complex of cryptic species that differ in many ecological respects, including damage-causing potential. Monitoring the genetic composition of B. tabaci populations in the field is, therefore, essential for achieving effective control. Sequencing is costly and time consuming; thus, efficient diagnostic tools must be developed to perform epidemiological studies involving hundreds of individuals. Here, we describe a polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) method for identifying all the putative species comprising the Africa/Middle East/Asia Minor group, including those that are the most devastating crop pests. Moreover, intra-specific diversity associated with specific symbiotic bacteria known to manipulate insect host phenotypes can also be detected. In addition, this method discriminates between the Africa/Middle East/Asia Minor and the Sub-Saharan African groups, which are sympatric in some areas. This simple, reliable and cost-effective diagnostic tool is ideal for the rapid analysis of a high number of individuals and, thus, has potential applications in field contexts, where it could provide valuable baseline information for pest management programs.

Roles of mating behavioural interactions and life history traits in the competition between alien and indigenous whiteflies

Interference competition between closely related alien and indigenous species often influences the outcome of biological invasions. The whitefly Bemisia tabaci species complex contains ≥28 putative species and two of them, Mediterranean (MED, formally referred to as the 'Q biotype') and Middle East-Asia Minor 1 (MEAM1, formally referred to as the 'B biotype'), have recently spread to much of the world. In many invaded regions, these species have displaced closely related indigenous whitefly species. In this study, we integrated laboratory population experiments, behavioural observations and simulation modelling to investigate the capacity of MED to displace Asia II 1 (AII1, formally referred to as the 'ZHJ2 biotype'), an indigenous whitefly widely distributed in Asia. Our results show that intensive mating interactions occur between MED and AII1, leading to reduced fecundity and progeny female ratio in AII1, as well as an increase in progeny female ratio in MED. In turn, our population cage experiments demonstrated that MED has the capacity to displace AII1 in a few generations. Using simulation models, we then show that both asymmetric mating interactions and differences in life history traits between the two species contribute substantially to the process of displacement. These findings would help explain the displacement of AII1 by MED in the field and, together with earlier studies on mating interactions between other species of the B. tabaci complex, indicate the widespread significance of asymmetric mating interactions in whitefly species exclusions.

Evidence for a new genetic variant in the Bemisia tabaci species complex and the prevalence of the biotype Q in southern Italy

The genetic diversity of Bemisia tabaci was investigated in Southern Italy using the mitochondrial cytochrome oxidase I (COI) gene as molecular marker and sampling whiteflies on cultivated plants, weeds and bushes. Phylogenetic analysis of COI sequences and restriction analysis of COI amplicons were used to genotype whitefly populations. A PCR-RFLP method based on digestion with the endonuclease ApoI was set up to identify the B. tabaci genetic variants so far recorded from the Mediterranean region. In general, biotype Q populations were most frequently collected (76.0% of all sampled populations). In greenhouse districts, 87.0% sampled populations were identified as biotype Q, and 13.0% were assigned to biotype B. Outside the greenhouse districts, the biotype B was never collected, whilst biotype Q populations were found on weeds and on plants cultivated in family gardens in different environments, also located in interior plains or in mountain areas distant from intensive cultivations of whitefly host plants. A new genetic variant unrelated to B and Q biotypes, which was named Ru, was collected on Rubus ulmifolius and grapevine. Phylogenetic analysis of COI sequences shown that Ru haplotypes form a well-supported clade sister to the clade including the Asian/Australian major genetic groups and the Italy major genetic group. The closest relative of the Ru clade (10.7% pairwise genetic distance) was the Italy group, with this latter so far including only the haplotypes of the T biotype. These results were discussed in the light of the recent B. tabaci species concept.

Diversity and Genetic Differentiation of the Whitefly Bemisia tabaci Species Complex in China Based on mtCOI and cDNA-AFLP Analysis

The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests. Two of the most prevalent cryptic species are B. tabaci Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED). In an extensive field survey of the B. tabaci complex present throughout part of China from 2004 to 2007, we obtained 93 samples of B. tabaci from 22 provinces. We determined that these Chinese haplotypes included 2 invasive species (MEAM1 and MED), and 4 indigenous cryptic species (Asia II 1, Asia II 3, China 3 and Asia II 7) by sequencing mitochondrial cytochrome oxidose one gene (mtCOI). The diversity and genetic differentiation of a subset of 19 populations of B. tabaci were studied using cDNA amplified fragment length polymorphism (AFLP). Prior to 2007, MEAM1 was a dominant species in many provinces in China. By 2007, MED was dominant in 11 provinces. Both invasive and indigenous species were simultaneously found in some regions. Indigenous species of B. tabaci were found in six provinces in southern China. MED and MEAM1 have broad ranges of host plants, and indigenous species appeared to have much narrower host ranges. All Asia II 3 samples were found on cotton except one on aubergine. China 3 has more host plants than Asia II 3. Twelve samples of China 3 were collected from sweet potato, Japanese hop, squash and cotton. A total of 677 reproducible bands amplified with 5 AFLP primer combinations were obtained. The highest proportion of polymorphic bands was 98.7% and the lowest was 91.9%. Unweighted pair-group method analysis indicated that the clustering was independent of the different species. MED showed the lowest degree of similarity than the other species. The data indicate that both MEAM1and MED were rapidly established in China.

CDNA Cloning of Heat Shock Protein Genes and Their Expression in an Indigenous Cryptic Species of the Whitefly Bemisia tabaci Complex from China

Thermal adaptation plays a fundamental role in shaping the distribution and abundance of insects, and heat shock proteins (Hsps) play important roles in the temperature adaptation of various organisms. To better understand the temperature tolerance of the indigenous ZHJ2-biotype of whitefly Bemisia tabaci species complex, we obtained complete cDNA sequences for hsp90, hsp70, and hsp20 and analyzed their expression profiles under different high temperature treatments by real-time quantitative polymerase chain reaction. The high temperature tolerance of B. tabaci ZHJ2-biotype was determined by survival rate after exposure to different high temperatures for 1 h. The results showed that after 41°C heat-shock treatment for 1 h, the survival rates of ZHJ2 adults declined significantly and the estimated temperature required to cause 50% mortality (LT50) is 42.85°C for 1 h. Temperatures for onset (Ton) or maximal (Tmax) induction of hsps expression in B. tabaci ZHJ2-biotype were 35 and 39°C (or 41°C). Compared with previous studies, indigenous ZHJ2-biotype exhibits lower heat temperature stress tolerance and Ton (or Tmax) than the invasive B-biotype.

The Bemisia tabaci Species Complex: Questions to Guide Future Research

Since 2007 we have began to consider the relationships between the different members of the Bemisia tabaci species complex in a more structured and systematic way. Much of these relationships has been infered from considerations of a portion of the mitochondrial cytochrome oxidase one (mtCOI) gene. While this is a quite limited approach which would benefit from the consideration of a much greater diversity of genetic material, it is the only publically available data that spans the diversity of the species complex. Despite the limitations, the phylogenetic reconstruction that can be derived from this data is useful and can be used as a basis to frame questions and construct testable hypotheses that will form the basis for future research. This study uses the largest available mtCOI dataset, consisting of 383 unique mtCOI haplotypes that spans the full diversity of the B. tabaci species complex as we currently know it, to make a range of observations which are then used to develop questions as guide for future research.

Evidence of diversity and recombination in Arsenophonus symbionts of the Bemisia tabaci species complex

BackgroundMaternally inherited bacterial symbionts infecting arthropods have major implications on host ecology and evolution. Among them, the genus Arsenophonus is particularly characterized by a large host spectrum and a wide range of symbiotic relationships (from mutualism to parasitism), making it a good model to study the evolution of host-symbiont associations. However, few data are available on the diversity and distribution of Arsenophonus within host lineages. Here, we propose a survey on Arsenophonus diversity in whitefly species (Hemiptera), in particular the Bemisia tabaci species complex. This polyphagous insect pest is composed of genetic groups that differ in many ecological aspects. They harbor specific bacterial communities, among them several lineages of Arsenophonus, enabling a study of the evolutionary history of these bacteria at a fine host taxonomic level, in association to host geographical range and ecology.ResultsAmong 152 individuals, our analysis identified 19 allelic profiles and 6 phylogenetic groups, demonstrating this bacterium's high diversity. These groups, based on Arsenophonus phylogeny, correlated with B. tabaci genetic groups with two exceptions reflecting horizontal transfers. None of three genes analyzed provided evidence of intragenic recombination, but intergenic recombination events were detected. A mutation inducing a STOP codon on one gene in a strain infecting one B. tabaci genetic group was also found. Phylogenetic analyses of the three concatenated loci revealed the existence of two clades of Arsenophonus. One, composed of strains found in other Hemiptera, could be the ancestral clade in whiteflies. The other, which regroups strains found in Hymenoptera and Diptera, may have been acquired more recently by whiteflies through lateral transfers.ConclusionsThis analysis of the genus Arsenophonus revealed a diversity within the B. tabaci species complex which resembles that reported on the larger scale of insect taxonomy. We also provide evidence for recombination events within the Arsenophonus genome and horizontal transmission of strains among insect taxa. This work provides further insight into the evolution of the Arsenophonus genome, the infection dynamics of this bacterium and its influence on its insect host's ecology.

Transcriptome analysis and comparison reveal divergence between two invasive whitefly cryptic species

BackgroundInvasive species are valuable model systems for examining the evolutionary processes and molecular mechanisms associated with their specific characteristics by comparison with closely related species. Over the past 20 years, two species of the whitefly Bemisia tabaci species complex, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED), have both spread from their origin Middle East/Mediterranean to many countries despite their apparent differences in many life history parameters. Previously, we have sequenced the transcriptome of MED. In this study, we sequenced the transcriptome of MEAM1 and took a comparative genomic approach to investigate the transcriptome evolution and the genetic factors underlying the differences between MEAM1 and MED.ResultsUsing Illumina sequencing technology, we generated 17 million sequencing reads for MEAM1. These reads were assembled into 57,741 unique sequences and 15,922 sequences were annotated with an E-value above 10-5. Compared with the MED transcriptome, we identified 3,585 pairs of high quality orthologous genes and inferred their sequence divergences. The average differences in coding, 5' untranslated and 3' untranslated region were 0.83%, 1.66% and 1.43%, respectively. The level of sequence divergence provides additional support to the proposition that MEAM1 and MED are two species. Based on the ratio of nonsynonymous and synonymous substitutions, we identified 24 sequences that have evolved in response to positive selection. Many of those genes are predicted to be involved in metabolism and insecticide resistance which might contribute to the divergence of the two whitefly species.ConclusionsOur data present a comprehensive sequence comparison between the two invasive whitefly species. This study will provide a road map for future investigations on the molecular mechanisms underlying their biological differences.

Performance on different host plants of an alien and an indigenous Bemisia tabaci from China

The capacity of the Middle East-Asia Minor 1 putative species of the whitefly Bemisia tabaci (Gennadius) species complex, commonly referred to as the ‘B biotype’, to invade has often been linked to its presumed wider host range than the indigenous competitors. To determine whether this alien putative species and the indigenous Asia II 1 whitefly putative species, commonly referred to as the ‘ZHJ2 biotype’, differ in their ability to use different host plants, we compared their development, survival and reproduction on eight crop species/cultivars that are commonly cultivated in Zhejiang, China. Of the eight host plants tested, B performed substantially better than ZHJ2 on squash, tomato and tobacco, B and ZHJ2 preformed equally well on cotton and sweet potato, while ZHJ2 performed better than B on kidney bean and pepper. These results indicate that while B generally has a wider host range than many indigenous B. tabaci, an indigenous B. tabaci can perform as well as or better on some host plants. These results combined with the cropping patterns in Zhejiang suggested that the differential capacity to use various host plants between whitefly species is important in mediating the process of invasion by an alien whitefly species.

Endosymbiont metacommunities, mtDNA diversity and the evolution of the Bemisia tabaci (Hemiptera: Aleyrodidae) species complex

Bemisia tabaci, an invasive pest that causes crop damage worldwide, is a highly differentiated species complex, divided into biotypes that have mainly been defined based on mitochondrial DNA sequences. Although endosymbionts can potentially induce population differentiation, specialization and indirect selection on mtDNA, studies have largely ignored these influential passengers in B.tabaci, despite as many as seven bacterial endosymbionts have been identified. Here, we investigate the composition of the whole bacterial community in worldwide populations of B.tabaci, together with host genetic differentiation, focusing on the invasive B and Q biotypes. Among 653 individuals studied, more than 95% of them harbour at least one secondary endosymbiont, and multiple infections are very common. In addition, sequence analyses reveal a very high diversity of facultative endosymbionts in B.tabaci, with some bacterial genus being represented by more than one strain. In the B and Q biotypes, nine different strains of bacteria have been identified. The mtDNA-based phylogeny of B.tabaci also reveals a very high nucleotide diversity that partitions the two ITS clades (B and Q) into six CO1 genetic groups. Each genetic group is in linkage disequilibrium with a specific combination of endosymbionts. All together, our results demonstrate the rapid dynamics of the bacterial endosymbiont-host associations at a small evolutionary scale, questioning the role of endosymbiotic communities in the evolution of the Bemisia tabaci species complex and strengthening the need to develop a metacommunity theory of inherited endosymbionts.

Mate Discrimination in Invasive Whitefly Species

Mate discrimination could be critical for invasive species that need to locate rare suitable mates and avoid costs associated with misdirected courtships to establish in new environments. Here, we tested whether individuals of two invasive whitefly species in the Bemisia tabaci species complex, commonly known as the B and Q biotypes, could discriminate between potential mates based on their species and sex. Behavioral observations showed that B females were more discriminating than Q females. Males of both species were able to discriminate between mates based on their species and sex, but in general B males discriminated more effectively than Q males. By incorporating these behavioral data into a conceptual model, we show that variation in mating behavior between females of different species was a more significant factor affecting mating than variation between males. These results indicate that mate discrimination could affect interactions between whitefly species and influence a species’ ability to colonize novel environments.

Mating behaviour, life history and adaptation to insecticides determine species exclusion between whiteflies

1. Negative interspecific interactions, such as resource competition or reproductive interference, can lead to the displacement of species (species exclusion). 2. Here, we investigated the effect of life history, mating behaviour and adaptation to insecticides on species exclusion between cryptic whitefly species that make up the Bemisia tabaci species complex. We conducted population cage experiments independently in China, Australia, the United States and Israel to observe patterns of species exclusion between an invasive species commonly referred to as the B biotype and three other species commonly known as biotypes ZHJ1, AN and Q. 3. Although experimental conditions and species varied between regions, we were able to predict the observed patterns of exclusion in each region using a stochastic model that incorporated data on development time, mating behaviour and resistance to insecticides. 4. Between-species variation in mating behaviour was a more significant factor affecting species exclusion than variation in development time. Specifically, the ability of B to copulate more effectively than other species resulted in a faster rate of population increase for B, as well as a reduced rate of population growth for other species, leading to species exclusion. The greater ability of B to evolve resistance to insecticides also contributed to exclusion of other species in some cases. 5. Results indicate that an integrative analysis of the consequences of variation in life-history traits, mating behaviours and adaption to insecticides could provide a robust framework for predicting species exclusion following whitefly invasions.

Tissue-specific gene silencing by RNA interference in the whitefly Bemisia tabaci (Gennadius)

The hemipteran whitefly Bemisia tabaci (Gennadius) species complex and the plant viruses they transmit pose major constraints to vegetable and fiber production, worldwide. The whitefly tissue- and developmental-specific gene expression has not been exhaustively studied despite its economic importance. In 2002, a functional genomic project was initiated, which generated several thousands expressed sequence tags (ESTs) and their sequence. This project provides the basic information to design experiments aimed at understanding and manipulating whitefly gene expression. In this communication, for the first time we provide evidence that the RNA interference mechanism discovered in many organisms, including in Hemiptera, is active in B. tabaci. By injecting into the body cavity long double-stranded RNA (dsRNA) molecules, specifically directed against genes uniquely expressed in the midgut and salivary glands, we were able to significantly inhibit the expression of the targeted mRNA in the different organs. Gene expression levels in RNAi-silenced whiteflies were reduced up to 70% compared to whiteflies injected with buffer or with a green fluorescent protein (GFP)-specific dsRNA. Phenotypic effects were observed in B. tabaci ovaries following dsRNA targeting the whitefly Drosophila chickadee homologue. Disruption of whitefly gene expression opens the door to new strategies aimed at curbing down the deleterious effects of this insect pest to agriculture.

Rapid identification of B biotype of Bemisia tabaci (Homoptera: Aleyrodidae) based on analysis of internally transcribed spacer 1 sequence

Abstract B biotype is a reasonably important biotype among all known biotypes in the Bemisia tabaci species complex. Local populations of B. tabaci on different host plants were collected from across the Chinese mainland, Taiwan, Pakistan and Israel. From each population of B. tabaci, an internally transcribed spacer region of the ribosomal rDNA gene was amplified, cloned and the sequence determined. Sequence homology analyses were performed and the results were similar to those based on morphology and biological characters. Based on analysis of the internally transcribed spacer 1 sequences, a B biotype-specific primer was designed. The PCR diagnosis results showed that B biotype is identifiable by a specific PCR product by using the forward diagnostic primer paired with a universal reverse primer. This diagnostic primer-based protocol can be used for preliminary analysis of mixed Bemisia populations containing B biotype, as well as other biotypes.

Mitochondrial DNA Evidence for a Distinct New World Group of <I>Bemisia tabaci</I> (Gennadius) (Hemiptera:Aleyrodidae) Indigenous to Argentina and Bolivia, and Presence of the Old World B Biotype in Argentina

Abstract A study was undertaken to establish the diversity within the Bemisia tabaci (Gennadius) species complex in Argentina using the mitochondria cytochrome oxidase I gene (mt COI) as a molecular marker. For one haplotype, common to cotton in the Santiago Province, biotic characters were evaluated, and included host range and life history traits: fecundity, generation time, intrinsic rate of increase, longevity, and rate of reproduction. To investigate genetic diversity, B. tabaci were collected from representative geographical locations and host plants in six provinces of Argentina. Also, B. tabaci found colonizing tomato plants in nearby Bolivia, which exhibited viruslike symptoms, were included in the study. We report, for the first time, the presence of the introduced ‘B’ biotype in Argentina, and present evidence for indigenous or ‘local’ B. tabaci haplotypes in both Argentina (ARG) and Bolivia (BOL), which collectively formed a distinctive, South American phylogeographic grouping of New World B. ...

Morphological and Mitochondrial DNA Marker Analyses of Whiteflies (Homoptera: Aleyrodidae) Colonizing Cassava and Beans in Colombia

Morphology of the third antennal segment and compound eyes of adults of the whitefly species Bemisia tabaci (Gennadius), B. argentifolii Bellows & Perring, B. tuberculata (Bondar), Trialeurodes vaporariorum (Westwood), T. variablilis (Quaintance), and Aleurotrachelus socialis (Bondar) were studied using scanning electron microscopy to aid in identification of adult whiteflies in cassava and beans in Colombia. Random amplified polymorphic DNA polymerase chain reaction markers proved complementary to the morphological identification of whitefly species and the only rapid method to distinguish individuals in the Bemisia tabaci species complex. From each species of whitefly, a region of the mitochondrial 16S rDNA gene was amplified, cloned and the sequence determined. Parsimony and distance analyses were performed and the results were similar to those based on morphology. The distance between the two species of Trialeurodes was greater than expected for two species within the same genus. The combination of morphological and molecular traits is useful in understanding the diversity and evolution of these whitefly species.