Whitefly Bemisia Tabaci Biotype Research Articles

Análise espaço-temporal de mosca-branca Bemisia tabaci (Genn., 1889) biótipo B (Hemiptera: Aleyrodidae) na cultura da soja, no município de Paragominas - Pará

The objective of this study is to evaluate the progress of whitefly Bemisia tabaci biotype B infestation during the crops of 2015, 2016 and 2017, to identify between crops studied in which they increased or decreased infestation and in which month the infestation was more representative, to identify among the cultivars which one or which are most susceptible to the attack and to map the areas of incidence of the whitefly. The research to obtain the data was carried out in the municipality of Paragominas and the data were obtained from Defense Agency of the State of Pará according to the methodology based on a model predefined by the agency. Climatic data on rainfall (mm) for crops were obtained through a database of the Brazilian Agricultural Research Corporation meteorological station. For statistical analysis of data, a database was built into Microsoft Excel spreadsheets. Data were analyzed through regression analysis and compared by the Tukey and Scott & Knott test. For the preparation of the whitefly infestation maps, the Spatial Analyst extension in the ArcGIS 10.1 software was used. In the studied area, the month of April is the one with the highest incidence of the pest, the crop of 2017 presented greater infestation, the cultivar P99R03 RR was the most susceptible to the attack of whitefly, and the cultivars P98Y51 RR and FT PGM, were more resistant to whitefly (B. tabaci) biotype B than the other cultivars.

Silverleaf whitefly-resistant common beans: an investigation of antibiosis and/or antixenosis

ABSTRACT The silverleaf whitefly Bemisia tabaci biotype B is one of the most important sucking pests of common bean, which causes severe damages and requires frequently synthetic insecticides spraying to protect crop productivity. The use of common bean cultivars resistant to whitefly attack is an important strategy within an integrated pest management (IPM) program. The biological development of B. tabaci confined to 17 bean genotypes was evaluated in greenhouse trials to verify the occurrence of antibiosis. Whitefly adults were released on plants of these genotypes to oviposit, afterward the incubation period of eggs, nymphal period, complete development period (egg–adult), and viability of the silverleaf whitefly nymphs were recorded. As main results, genotype CHIP 300 prolonged the developmental period from egg to adult (~10 days) and BRS Estilo, Arcelina 4, IPR Garca, Tybata, CHIP 300, IPR Eldorado, H96A102-1-1-1-52, SCS-202-Guara and CHIB 06 caused nymphal mortality, suggesting high levels of antibiosis and/or antixenosis. These genotypes may be helpful in common bean breeding programs aimed at developing commercial cultivars resistant to B. tabaci biotype B.

Intervalo de aplicação do Azamax® sobre pragas sugadoras do algodoeiro e seus inimigos naturais

O algodoeiro é atacado por pragas sugadoras que têm sido controladas com inseticidas químicos, causando problemas à saúde do aplicador e poluição do meio ambiente, mas o uso de produtos botânicos como o nim vem sendo estudado nos últimos anos. O efeito do intervalo de aplicação do inseticida Azamax® foi avaliado sobre pragas sugadoras e seus inimigos naturais. O estudo foi conduzido na Embrapa Algodão em Barbalha, Ceará. O Azamax® foi aplicado em dois intervalos de aplicação (sete e 15 dias), em cobertura total das plantas com pulverizador costal manual com bico cônico. As amostragens foram realizadas semanalmente em 40 plantas por parcela dos 13 aos 90 dias após a emergência das plantas. Pulgão, tripes e a cochonilha foram amostrados nos ponteiros das plantas, a mosca branca na folha do 5º nó e o ácaro vermelho na parte mediana, enquanto os inimigos naturais, nos locais onde as pragas foram amostradas. O Azamax® aplicado aos sete e 15 dias reduz a taxa de infestação do pulgão Aphis gossypii, assim como, a mosca branca Bemisia tabaci biótipo B e a cochonilha Planococcus minor, não tendo efeito no ácaro vermelho, para os dois períodos de aplicação. Não foi observado efeito direto do Azamax® sobre a população dos inimigos naturais das principais pragas sugadoras do algodoeiro.

Selection of tomato genotypes for processing resistant to spider mite and whitefly

The objective of the research was to select genotypes from the second generation of the first backcross (F 2 BC 1 ) between the tomato cultivar for processing S. lycopersicum cultivar Redencao and the wild access S. habrochaites var. hirsutum PI-127826, with high levels of zingiberene (ZGB), resistant to the mite Tetranychus urticae Koch and the whitefly ( Bemisia tabaci biotype B). From the F 2 BC 1 population the ZGB content was quantified and then five plants with high zingiberene was selected (RVTZ 2011-079-117, RVTZ 2011-079-185, RVTZ 2011-079-335, RVTZ 2011-079-345 and RVTZ 2011-079-503) and four with low zingiberene content (RVTZ 2011-079-417, RVTZ 2011-331-460, RVTZ 2011-079-538 and RVTZ 2011-079-548). Genotypes selected for high and low ZGB content and the parentals S. habrochaites var. hirsutum access PI-127826 and ‘Redencao’ were evaluated for repellency to the mite T. urticae and the whitefly Bemisia tabaci biotype B. There was a significant and inverse correlation between ZGB content and average distances traveled by mites on tomato leaflets. Plants of PI-127826, wild parental with high ZGB content, showed averages for number of whitefly eggs significantly lower in relation to the group of F 2 BC 1 , genotypes with low-ZGB. Genotypes of the F 2 BC 1 generation with high zingiberene levels RVTZ 2011-079-117, RVTZ 2011-079-185, RVTZ 2011-079-335, RVTZ 2011-079-345 and RVTZ 2011-079-503 are promising for progress in achieving lines with background for processing, resistant to arthropod pests. Among them RVTZ 2011-079-117 stands out for both pests evaluated.

Biodiversity provides whitefly biological control based on farm management

Management of the whitefly Bemisia tabaci biotype B (Hemiptera: Aleyrodidae) has challenged scientists and famers worldwide because this insect is highly polyphagous and resistant to traditional control methods. Innovative management tools, such as the use of the ecosystem service of biological control, are necessary, especially in a century in which sustainable crop systems are emerging. We investigated how management practices and farm diversity within the property limits affect the relationship between biodiversity conservation and the biological control of B. tabaci. We determined the mortality factors of whitefly nymph cohorts on 33 small farms growing tomatoes. The sampled farms formed a gradient of increasing farm diversity and decreasing management intensity. The diversity of natural enemies increased from conventional to agroecological farms, and predation was identified as the key mortality factor of B. tabaci nymphs on all farm types except the conventional farms. Biological control provided by biodiversity components (predators, parasitoids and pathogens) was enhanced on more diverse and less intensively managed farms. Higher predator richness and abundance resulted in more effective biological control and made it less variable among farms. Different components of natural enemy biodiversity were conserved and acted in a complementary way on agroecological farms, and the enhanced ecosystem services reduced the need for insecticides.

RNA1-Independent Replication and GFP Expression from Tomato marchitez virus Isolate M Cloned cDNA.

Tomato marchitez virus (ToMarV; synonymous with Tomato apex necrosis virus) is a positive-strand RNA virus in the genus Torradovirus within the family Secoviridae. ToMarV is an emergent whitefly-transmitted virus that causes important diseases in tomato (Solanum lycopersicum) in Mexico. Here, the genome sequence of the ToMarV isolate M (ToMarV-M) was determined. We engineered full-length cDNA clones of the ToMarV-M genomic RNA (RNA1 and RNA2), separately, into a binary vector. Coinfiltration of both triggered systemic infections in Nicotiana benthamiana, tomato, and tomatillo (Physalis philadelphica) plants and recapitulated the biological activity of the wild-type virus. The viral progeny generated from tomato and tomatillo plants were transmissible by the whitefly Bemisia tabaci biotype B. Also, we assessed whether these infectious clones could be used for screening tomato cultivars for resistance to ToMarV and our results allowed us to differentiate resistant and susceptible tomato lines. We demonstrated that RNA1 of ToMarV-M is required for the replication of RNA2, and it can replicate independently of RNA2. From this, ToMarV-M RNA2 was used to express the green fluorescent protein in N. benthamiana plants, which allowed us to track cell-to-cell movement. The construction of full-length infectious cDNA clones of ToMarV-M provides an excellent tool to investigate virus-host-vector interactions and elucidate the functions of torradovirus-encoded proteins or the mechanisms of replication of torradovirus genomic RNA.

Use of Posttranscription Gene Silencing in Squash to Induce Resistance against the Egyptian Isolate of the Squash Leaf Curl Virus.

Squash leaf curl virus (SqLCV) is a bipartite begomovirus affecting squash plants. It is transmitted by whitefly Bemisia tabaci biotype B causing severe leaf curling, vein banding, and molting ending by stunting. In this study full-length genomic clone of SqLCV Egyptian isolated and posttranscriptional gene silencing (PTGS) has been induced to develop virus resistance. The Noubaria SqLCV has more than 95% homology with Jordon, Israel, Lebanon, Palestine, and Cairo isolates. Two genes fragment from SqLCV introduced in sense and antisense orientations using pFGC5049 vector to be expressed as hairpin RNA. The first fragment was 348 bp from replication associated protein gene (Rep). The second fragment was 879 bp representing the full sequence of the movement protein gene (BC1). Using real-time PCR, a silencing record of 97% has been recorded to Rep/TrAP construct; as a result it has prevented the appearance of viral symptoms in most tested plants up to two months after infection, while construct containing the BC1 gene scored a reduction in the accumulation of viral genome expression as appearing in real-time PCR results 4.6-fold giving a silencing of 79%, which had a positive effect on symptoms development in most tested plants.

The virulence of entomopathogenic fungi against Bemisia tabaci biotype B (Hemiptera: Aleyrodidae) and their conidial production using solid substrate fermentation

The virulence of five isolates of Beauveria bassiana, five of Isaria fumosorosea and four of Lecanicillium muscarium from Brazil was determined on whitefly Bemisia tabaci biotype B lifestages on bean leaves under laboratory conditions. The conidial yield (on cadavers or parboiled rice), surface hydrophobicity and enzyme activity were also determined. The isolates of B. bassiana and I. fumosorosea were the most virulent against nymphs (71–86% mortality within 8d), with LT50 values ranging from 3 to 4d after treatment with 107conidia/mL (150conidia/mm2). Spore production on nymph cadavers reached 4–8×105conidia/insect. The L. muscarium isolates demonstrated low virulence toward nymphs. After spraying eggs with 1×108conidia/mL (1674conidia/mm2) of B. bassiana and I. fumosorosea, most nymphs hatched, but then 40–70% of these nymphs were infected by indirect exposure of conidia on the leaves. Adults exposed to treated leaf disks (150conidia/mm2) were more susceptible to I. fumosorosea than to B. bassiana. The enzyme activity (Pr1) and the relative conidial surface hydrophobicity were not correlated with any virulence parameter measured for either B. bassiana or I. fumosorosea. In addition, the highest conidial yields on parboiled rice using solid-state fermentation (4.9–11.4×109conidia/g) were achieved by isolates of I. fumosorosea CG1228 and B. bassiana CG1229. I. fumosorosea CG1228 was highly virulent against whitefly nymphs and adults as well as attained high spore production on insect cadavers and parboiled rice. Our results indicate that I. fumosorosea CG1228 has desirable attributes for the development of a mycoinsecticide against B. tabaci biotype B.

New experimental tools for bioassays with whitefly in laboratory

The objective of this work was to develop an experimental kit for assessments of repellency, deterrence for oviposition, and insecticidal activity on adults of the whitefly Bemisia tabaci biotype B. The kit, which consisted of arenas and nebulizer, was effective for conducting bioassays, and the application of aqueous extracts by inhaler was adequate. The techniques are simple, cheap, and may contribute to research on this insect.

First Report of Tomato chlorosis virus in Potato in Brazil.

Potato plants (Solanum tuberosum cv. Ágata) exhibiting symptoms of leaf roll and interveinal chlorosis, especially on older leaves, were found in a commercial crop in the County of Cristalina, State of Goiás, Brazil in June 2011. The crop was severely infested by whitefly Bemisia tabaci biotype B. Four potato tubers from symptomatic plants were indexed for the presence of the following viruses: Tomato chlorosis virus (ToCV), Potato leaf roll virus (PLRV), Tomato severe rugose virus (ToSRV), and Potato virus Y (PVY). Total RNA was extracted separately from each tuber and used for reverse transcription (RT)-PCR using the HS-11/HS-12 primer pair, which amplifies a fragment of 587 bp from the highly conserved region of the heat shock protein (HSP-70) homolog gene reported for ToCV. The RT-PCR product was subsequently tested by nested-PCR for detection of ToCV with specific primers ToC-5/ToC-6 (2). Amplicons of 463 bp, amplified from total RNA separately extracted from three tubers, were purified and directly sequenced. Comparisons among the three consensus sequences of 448 bp (GenBank Accession Nos. JQ288896, JQ288897, and JQ288898) revealed respectively, 98, 100, and 100% identity with the reported sequence of a tomato isolate of ToCV from Brazil (GenBank Accession No. EU868927) (1). For ToSRV detection, total DNA was extracted from two tubers and a fragment of approximately 820 bp was amplified by PCR with specific primers (3). PLRV and PVY were indexed in two and three tubers, respectively, by double-antibody sandwich-ELISA (SASA, Edinburg, Scotland). Virus-free B. tabaci biotype B were separately transferred to potato and tomato leaves infected with ToCV for an acquisition access period of 24 h. Groups of 30 viruliferous whitefly were transferred to four, young, sprout-grown potato plants cv. Ágata (two plants per virus isolate) for 24-h inoculation access period. After 37 days of inoculation, one plant inoculated with the potato and tomato isolates of ToCV, respectively exhibited symptoms of leaf roll and interveinal chlorosis on order leaves, which were similar to that induced by PLRV. Experimental infection of potato plants with ToCV, which induced leaf roll symptoms resembling PLRV infection, was reported in the United States by Wisler et al. (4). The potato isolate of ToCV was also transmitted by B. tabaci to one of two inoculated tomato plants. The presence of ToCV in all inoculated plants was detected by nested-RT-PCR as described above. To our knowledge, this is the first report on detection of ToCV in field potato plants in the world. Considering that ToCV occurs in innumerous countries around the world, it is transmitted by a cosmopolitan insect, and it induces symptoms similar to PLRV, this finding triggers an alert to field dependent seed-potato multiplication, virus inspector, and certification system.

Detection and identification of Clerodendron golden mosaic China virus in Salvia splendens

Two viral DNAs were obtained by rolling circle amplification conducted on DNA extracts from salvia (Salvia splendens) cv. ‘Dancing Flame’ showing variegated foliage resembling virus symptoms. Sequence analyses revealed the presence of an isolate of the putative begomovirus Clerodendron golden mosaic China virus. The virus was detected in all salvia plants showing variegated foliage, but not in non-variegated plants. The virus was graft-transmitted to healthy salvias which reproduced the original symptoms. Attempts to transmit the virus with the whitefly Bemisia tabaci biotype B failed. The results of this investigation strongly suggest that the salvia isolate of Clerodendron golden mosaic China virus (ClGMCNV-Sal[USA:LA:11]) is the cause of the variegated foliage of S. splendens cv. ‘Dancing Flame’. This is the first report of this virus in the United States.

First Report of Sida micrantha mosaic virus in Phaseolus vulgaris in Brazil.

Snap and common beans (Phaseolus vulgaris L.) are severely affected by Bean golden mosaic virus (BGMV) infection, so far the only begomovirus reported on these crops in Brazil (1). Samples of snap and common beans colonized by the whitefly Bemisia tabaci biotype B and displaying golden mosaic, chlorotic spots, and leaf distortion were collected in three production regions in Goiás State (Goianápolis, Luziânia, and Itaberaí) between 2003 and 2007. Total DNA extracted from leaf samples was used as template in PCR assays using universal primers targeting conserved regions of the DNA-A and DNA-B genomes (3). Begomovirus-specific amplicons were observed only with DNA template from symptomatic plants. Two single amplicons were observed for both genomic segments, indicating the presence of bipartite species in all samples. Sequence analysis of four isolates (named as GO-176, GO-260, GO-354, and GO-368) obtained from common bean samples indicated identity levels of approximately 95% with the DNA-A segment of BGMV (GenBank Accession No. FJ665283). However, the complete DNA-A sequence (GenBank Accession No. HM357459.1) of the GO-060 isolate (from a symptomatic snap bean plant collected in Goianápolis) displayed 76% identity with BGMV (GenBank Accession No. FJ665283) and 95% identity with the DNA-A of a Sida micrantha mosaic virus (SimMV) isolate (GenBank Accession No. EU908733.1) reported to be infecting okra (Abelmoschus esculentus L.) and 94.8% with a SimMV isolate reported to be infecting soybean (GenBank Accession No. FJ686693) in Brazil (2). Koch's postulates were fulfilled for the isolate GO-060 by inoculating a set of soybean and bean accessions via a biolistic approach. The ratio of positive PCR amplicons per total of inoculated plants were 15 of 16 for snap bean cv. Trepador, 9 of 10 for snap bean cv. Fartura, 18 of 24 for common bean cv. Olate Pinto, and 19 of 25 for common bean cv. Carioca. The isolate was also able to infect eight of nine soybean 'Doko' plants. Sequence analysis using symptomatic leaf samples (15 days after inoculation) confirmed SimMV as the causal agent. To our knowledge, this is the first report of a SimMV isolate infecting P. vulgaris. This virus is apparently fast expanding its host range from Malvaceae to Solanaceae species and leguminous hosts after the introduction of B. tabaci biotype B (2). More extensive surveys are necessary to access the current epidemiological importance of SimMV in both snap and common beans in Brazil.

Development of leaf silvering in squash cultivars infested by silverleaf whitefly

The silverleaf whitefly Bemisia tabaci biotype B is one of the most harmful insect pests for agricultural and vegetable crops. Beside the direct damage, it transmits pathogenic virus and induces plant physiological disorders, such as the squash silverleaf disorder. In this research we evaluated the development of leaf silvering in squash cultivars submitted to artificial infestation of B. tabaci biotype B. An experiment was conducted under field conditions, in Campinas, São Paulo State, Brazil, during the season 2003-2004. The germplasm (Cucurbita spp.) comprised of seven cultivars of summer squash and nine of bush squash. The experiment used a complete randomized blocks design, with 16 treatments (cultivars) and five replications. Each plot consisted of two plants. The artificial infestation was done when the plants emitted the third pair of leaves, by transplanting soybean plants infested with silverleaf whitefly between the squash plots. The leaf silvering was evaluated every two or three days, using a rating scale varying from 1 (no symptom) to 5 (leaves completely silvered). The highest level (5.0) was observed in 'Baianinha', 'Golden Delight', 'Caravela' and 'Arlika', while 'Novita' (2.5), 'Atlas' (2.0) and 'Atlanta AG-303' (1.5) showed light symptoms, indicating that these have low sensibility to this physiological disorder.

Transmissão do Cowpea mild mottle virus pela mosca branca Bemisia tabaci biótipo B para plantas de feijão e soja

A necrose da haste da soja é causada por um vírus do gênero Carlavirus transmitido pela mosca branca Bemisia tabaci, também infectante de feijão e identificado como Cowpea mild mottle virus (CpMMV). Neste trabalho foram realizados testes para determinação do número de moscas-brancas B. tabaci biótipo B necessários para transmissão do vírus em feijoeiro e soja. Na sequência foram realizados dois outros testes, com 10 insetos por planta. Avaliaram-se períodos de acesso à aquisição (PAA) de 'Jalo' para 'Jalo', e o efeito de períodos de acesso à inoculação (PAI). Foram visualmente constatados sintomas típicos do carlavírus como mosaico, clareamento de nervuras, necrose sistêmica e redução de crescimento. Houve transmissão do vírus para 'BT-2' de feijão e 'BRS-132' de soja com apenas um inseto por planta, sendo mais eficaz nesta última espécie. A taxa de transmissão do vírus foi maior com o aumento do número de insetos por planta. E o PAA foi determinado após 15' de tempo para aquisição, e o PAI com 5 min e aumentando os períodos de acesso a aquisição e inoculação aumentou-se a taxa de transmissão.

Whiteflies (Bemisia tabaci) issued from eggs bombarded with infectious DNA clones of Tomato yellow leaf curl virus from Israel (TYLCV) are able to infect tomato plants.

We have reported previously that Tomato yellow leaf curl virus from Israel (TYLCV) penetrates the reproductive system of its vector, the whitefly Bemisia tabaci biotype B, and may be transmitted to progeny. In order to mimic this phenomenon and to understand how TYLCV accompanies the development of the insect, we have bombarded B. tabaci eggs with an infectious DNA clone of TYLCV. After a linear full-length genomic copy of TYLCV DNA was delivered to eggs, the DpnI-sensitive DNA became circular and DpnI resistant. When a dimeric copy of TYLCV DNA was delivered to eggs, the viral DNA was detected in all the whitefly developmental stages. Adult insects that developed from the treated eggs were able to infect tomato test plants with variable frequency. Viral DNA was detected in the progeny of whiteflies that developed from eggs bombarded with TYLCV. Similarly, when insect eggs were bombarded with a dimeric copy of an infectious clone of the genome of Tomato yellow leaf curl virus from Sardinia, Italy (TYLCSV), adults that eclosed from the treated eggs were able to infect tomato test plants.