Academic literature on the topic 'B.tabaci'

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is a major insect pest of poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch; Family: Euphorbiaceae) in the greenhouse. Currently, neonicotinoids are widely used for B.tabaci management in the greenhouse, which is less favored by the consumers because of the potential nontarget effects of these insecticides on beneficial insects. Little is known on how the high spray volumes of spinetoram (20%) + sulfoxaflor (20%) (XXpire®) affect the B.tabaci population in the greenhouse. The objective of the study was to determine the efficacy of spinetoram + sulfoxaflor and dinotefuran (Zylam®) applied as foliar-spray volumes (high, referred to as spench, and low, referred to as foliar) and soil drench against B.tabaci. The high foliar-spray volume application (spench) of both insecticides reduced the B.tabaci immature densities, compared with low foliar-spray volume (foliar) and soil drench applications. The soil drench application did not provide adequate B.tabaci control regardless of insecticide type. Spinetoram + sulfoxaflor applied as a high-spray volume treatment was moderately effective in controlling B.tabaci nymphs relative to nontreated control.

The efficiency of sulfoxaflor, cyantraniliprole, imidacloprid and azadirachtin were evaluated against whitefly, Bemisia tabaci on tomato under field conditions. Two experiments in season 2021 showed that sulfoxaflor , cyantraniliprole and imidacloprid were the most effective insecticides compared to azadirachtin. Sulfoxaflor gave the highest reduction of B.tabaci one day after treatment (initial kill). The results also showed that the infestation of B.tabaci can be greatly reduced by spraying sulfoxaflor and cyantraniliprole. Tomato fruit yield was significantly increased after an application of all the tested insecticides when compared to untreated control. All the insecticides caused a slight but significant decrease in fruit quality attributes. Overall, our findings indicated that sulfoxflor and cyantraniliprole can suitably be included in IPM program of whitefly control in tomato. However, the potential side effects on tomato fruit should be considered.

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is an important agricultural pest worldwide. Uridine diphosphate (UDP)-glucuronosyltransferases (UGTs) are one of the largest and most ubiquitous groups of proteins. Because of their role in detoxification, insect UGTs are attracting increasing attention. In this study, we identified and analyzed UGT genes in B. tabaci MEAM1 to investigate their potential roles in host adaptation and reproductive capacity. Based on phylogenetic and structural analyses, we identified 76 UGT genes in the B. tabaci MEAM1 genome. RNA-seq and real-time quantitative PCR (RT-qPCR) revealed differential expression patterns of these genes at different developmental stages and in association with four host plants (cabbage, cucumber, cotton and tomato). RNA interference results of selected UGTs showed that, when UGT352A1, UGT352B1, and UGT354A1 were respectively silenced by feeding on dsRNA, the fecundity of B. tabaci MEAM1 was reduced, suggesting that the expressions of these three UGT genes in this species may be associated with host-related fecundity. Together, our results provide detailed UGTs data in B.tabaci and help guide future studies on the mechanisms of host adaptation by B.tabaci.

Indicator Plant and PCR-RAPD for Biotype Determination of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae).B. tabaci has been known world wide as a major pest and virus vector of horticulture. In Indonesia the presence of B.tabaci was reported since 1980 and its role as virus vector in tomato and chilli pepper has becoming more importantrecently. Genetic diversity of B. tabaci has been well recognized, but very little information available for diversity of B.tabaci in Indonesia. This research was conducted in Bogor, West Java from May 2004 to June 2005. The aim of thisresearch was to initiate basic information regarding genetic diversity of B. tabaci in Indonesia, particularly in Java Island.Whiteflies population collected from different crops, i.e. tomato, broccoli, chill pepper, eggplant, cucumber, soybean, andedamame, was evaluated using silverleaf-induction test, and RAPD-PCR. It was evidenced that only B. tabaci populationfrom broccoli was able to induce silverleaf. Two genetic types of B. tabaci, i.e. biotype B and non B, were identified basedon polymorphism character of DNA. Population from broccoli was belong to biotype B, whereas other populations fromtomato, chill pepper, eggplant, cucumber, soybean, and edamame were belong to biotype non B.

The whitefly, B.tabaci is a major pest of agricultural crops which transmits begomovirus in a species-specific manner. Yellow vein mosaic disease (YVMD) and okra leaf curl disease (OLCD) caused by distinct begomovirus are a major limitation to production of okra in India. In this framework the present investigation reports, for the first time, comparative study of begomovirus species viz. yellow vein mosaic virus (YVMV) and okra enation leaf curl virus (OELCuV) ingested and egested by two cryptic species (Asia I and Asia II 5) of B.tabaci at different time interval using detached leaf assay. A gradual increase of both virus copies were observed with increased feeding exposure in Asia I and Asia II 5. Both the genetic groups of whitefly could acquire the viruses within just 5 minutes of active feeding however, a significant amount of variation was noted in virus uptake by the both. At 24 hours of active feeding Asia II 5 acquired more of YVMV whereas, Asia I ingested more OELCuV. Similarly, the genetic group acquiring higher titre of virus egested higher amount during inoculation period. On the whole, it can be presumed that Asia I is a more effective transmitter of OELCuV whereas, Asia II 5 of YVMV further suggesting increased risk of virus pandemics (both YVMV and OELCuV) in regions where Asia I and Asia II 5 is dominant.

Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a worldwide pest that damages over 900 host plant species. The volatile organic compounds (volatiles) of contrasting plants, as well as their growth stage, influence this pest’s infestation behavior. The chemical contents of volatiles isolated from three plants (Gossypium hirsutum, Abutilon theophrasti, and Ricinus communis) during various growth phases (pre-flowering, fluorescence, and fruiting) were examined, as well as their influence on the behavior of adult B. tabaci. The olfactometer studies demonstrated that growth periods of the three plants affected the preference of B. tabaci. Volatiles of piemarker and cotton plants had dissimilar levels of attraction to adults during all stages. Volatile substances released by the castor at the stage of flowering had repellent effect on B. tabaci. In the plant versus plant combination, piemarker volatiles before and during anthesis were most preferred by adults, followed by cotton and then castor. A total of 24, 24, and 20 compounds were detected from volatiles of piemarker, cotton, and castor, respectively, and proportions among the compounds changed during different stages of plant development. The olfactory responses of B. tabaci to volatile compounds presented that linalool and high concentration of (Z)-3-hexenyl acetate had a strong trapping effect on this pest, while nonanal had a significant repellent effect at high concentration. This study indicates that distinct plants and their growth stage affect their attractiveness or repellency to B.tabaci adults, which are mediated by changing plant volatiles. These compounds obtained by analysis screening can be adopted as potential attractants or repellents to control Mediterranean (MED) B. tabaci.

AbstractAfrican cassava mosaic virus (ACMV), vectored by the whitefly, Bermisia tabaci (Gennadius), is considered the most damaging pathogen of any African crop. Information about vector movement is important for understanding the epidemiology of this disease and the experiments reported here were designed to examine B.tabaci flight activity both in and around a cassava crop in relation to time of day, crop growth stage, wind direction and speed, and to the resulting pattern of infected plants within the field at harvest. At wind speeds of <0.4 ms−1 adult B. tabaci approached the yellow traps by flying upwind. At greater wind speeds, significantly fewer B. tabaci adults approached the traps from downwind, thus reversing the directionally of the catch. When the direction of the prevailing south-west wind reversed, so did the directionality of the catch. Bemisia tabaci adults were flight active throughout the day and the greatest percentage were caught above the canopy between 06.00–08.00 h, when wind speeds were lowest. Trap height and position significantly affected catch with the greatest numbers caught on the lowest traps. More than three times as many B. tabaci adults were caught on traps situated downwind from the field compared to those upwind. Suggesting that the field was acting as a source of whiteflies. In both years, Africa cassava mosaic disease (ACMD) incidence was highest and lowest, respectively, on the edges and in the middle of the trials, with the highest incidence occuring on the edges facing the prevailing wind direction. These results are discussed in relation to the epidemiology of ACMD and to potential cultural control methods such as the use of ACMD-resistant guard rows to protect a mainly susceptible crop.

Abstract Background Three of entomopathogenic fungi, identified as Isariajavanica (Cjc-03 and Cjw-01) and Purpureocilliumlilacinum (TS-01) were found naturally infecting the whiteflies, Bemisiatabaci (Gennadius) (Hemiptera: Aleyrodidae) on chili and tomato plants. All the isolates were identified by morphological characterization and molecular identification (ITS region amplification). The virulence of the three isolates was evaluated against nymphs of B.tabaci at three different concentrations (1 × 106, 1 × 107, and 1 × 108 conidia/ml) under laboratory conditions and on adults of B.tabaci at one conidia concentration (1 × 107 conidia/ml) under laboratory and glasshouse conditions. Results Isariajavanica showed the highest virulence against B.tabaci nymphs and adults in both laboratory and glasshouse conditions. I.javanica exhibited the highest mortality in the laboratory against B.tabaci, nymphs at the highest concentration (1 × 108 conidia/ml) 8 days post-inoculation. Likewise, in the laboratory bioassay, B.tabaci, adults, Cjc-03 isolate exhibited maximum mortality (80.0%), followed by Cjw-01 isolate (77.5%), and TS-01 isolate (65.0%) at the concentration of 1 × 107 conidia/ml at 7 days post-inoculation. The highest mortality rate (63.45%) was recorded by the Cjc-03 isolate and TS-01 (54.22%) isolate at 3 days post-inoculation in glasshouse bioassay using the concentration of 1 × 107 conidia/ml of each of the 2 isolates (Cjc-03 and TS-01) against B.tabaci adults. Conclusion Overall, the findings showed that both isolates of I.javanica and P.lilacinum reduced the number of eggs, nymphs, and adults’ emergence of B.tabaci, following the application of 1 × 107 conidia/ml on tomato leaves in the glasshouse. The newly isolated strains could be developed as a potential commercial biopesticide for managing B.tabaci.

Whitefly, Bemisia tabaci (Gennadius), is a widespread polyphagous insect pest and a dangerous vector for many viruses that cause plant diseases. Farmers urgently need safe pesticides to protect their crops and plants, making biopesticide a good alternative to chemicals. Biopesticides are part of an integrated pest management program and offer a safer, more natural alternative to chemical pesticides. Since biocides were introduced, several pest management products have been released, some of which dominate the market. The current laboratory study tested the biological agent Aspergillus niger at three concentrations (0.25, 0.50, and 1.00 con/ml) to manage and reduce Bemisia tabaci population density in greenhouses and field crops. Laboratory tests showed that the two isolates were highly virulent against Bemisia tabaci nymphs and adults. Mortality was significantly different from controls in relation to isolate concentrations and time. Culture filtrate concentration and duration affected nymph and adult mortality. The 100% concentrations of both An1 and An2 were superior to the remaining concentrations, giving mortality in nymphs of B.tabaci 48.88 and 45.55 for isolates (An1 and An2) respectively, 42.21 and 36.66 for isolates (An1 and An2) respectively in adults stage. Effect of duration on post treatment mortality, highest mortality in nymphs and adults occurred 9 days after treatment, 74.44 , 56.66% in nymph and 53.33, 45.55 in adults for isolates (An1and An2) respectively. Concerning the interaction between concentration and duration, as is clear from Tables (1) and (2), the mortality was highest at 1.00% concentration. After 9 days of treatment, the isolates (An1, An2) achieved mortality 86.66, 80.0 in nymphs and 73.33%, 63.33% in adults, respectively. These findings demonstrate A. niger's biopesticide potential.

Manipulation of insect vector behavior by virus-induced plant volatiles is well known. But how the viral disease progression alters the plant volatiles and its effect on vector behavior remains less explored. Our studies tracked changes in volatile profile in progressive infection stages of cotton leaf curl virus (CLCuV) infected plants and their effect on B. tabaci behavior. Significant differences in virus titers were noticed between progressive infection stages showing distinct symptoms. Whiteflies initially settled on CLCuV infected plants, but their preference was shifted to healthy plants over time. GC-MS analysis revealed subtle quantitative/qualitative changes in volatile organic compounds (VOCs) between the healthy and selected CLCuV infection stages. VOCs such as hexanal, (E)-2-hexen-1-ol, (+)-α-pinene, (−)-β-pinene, (Z)-3-hexen-1-ol, (+)-sylvestrene, and (1S,2E,6E, 10R)-3,7,11,11-tetramethylbicycloundeca-2,6-diene (Bicyclogermacrene) were associated with the infection stage showing upward curling of leaves; (E)-2-hexen-1-ol, β-myrcene, β-ocimene, and copaene were associated with the infection stage showing downward curling. Validation studies with eight synthetic VOCs indicated that γ-terpinene elicited attraction to B. tabaci (Olfactometric Preference Index (OPI) = 1.65), while β-ocimene exhibited strong repellence (OPI = 0.64) and oviposition reduction (66.01%–92.55%). Our studies have demonstrated that progression of CLCuV disease in cotton was associated with dynamic changes in volatile profile which influences the behavioural responses of whitefly, B.tabaci. Results have shown that VOCs such as (+)-α-pinene, (−)-β-pinene γ-Terpinene, α-guaiene; 4- hydroxy- 4 methyl-2- pentanone and β-ocimene emitted from Begomovirus infected plants could be the driving force for early attraction and later repellence/oviposition deterrence of B. tabaci on virus-infected plants. The findings of this study offer scope for the management of whitefly, B. tabaci through semiochemicals.

L’étude de la richesse spécifique et génétique des ravageurs des cultures, vecteurs de virus phytopathogènes, dans un contexte d’invasion biologique en milieu continental, est indispensable pour la compréhension des mécanismes qui sous-tendent les émergences virales en Afrique Sub-saharienne. Le complexe d’espèce cryptique de Bemisia tabaci est composé de nombreuses espèces dont le groupe d’espèces Sub-Sahariennes qui sont inféodées au manioc en Afrique. Celles-ci sont directement impliquées dans la vection de nombreux virus provoquant la maladie de la mosaïque du manioc (CMD) ou celle de la striure brune (CBSV). Ces maladies entrainent de fortes pertes de rendement sur les cultures de manioc, qui figurent parmi les principales plantes à racine amylacées cultivées du continent Africain. Malgré les études réalisées, la diversité des espèces d’aleurodes sur manioc dans certains pays reste inconnue. En outre, peu d’information existe sur les flux de gènes au sein des espèces et potentiellement des sous-groupes génétiques récemment décrit au sein de ces espèces. C’est dans ce contexte que nous avons réalisé une étude génétique de 898 échantillons de Centrafrique et de 667 échantillons du Cameroun au moyen de marqueurs nucléaires (microsatellites) et mitochondrial (COI). Ces analyses ont permis la caractérisation de la variabilité génétique et de la différenciation intra et inter espèce. L’effet de possibles facteurs tels que la plante-hôte et l’origine géographique des individus analysés, souvent rapportés comme facteurs de structuration génétique chez l’espèce B. tabaci ont également été testés pour (i) déterminer la nature des espèces en circulation dans ces pays, (ii) comprendre la répartition de ces populations, (iii) évaluer l’étendue de leur diversité et structuration génétique, et (iii) considérer l’apport de ces connaissances dans la gestion des populations d’Afrique centrale. Nous avons ainsi pu décrire la présence en Centrafrique et au Cameroun de 6 espèces du complexe de B. tabaci et de 5 des sous-groupes d’une espèce (SSA1) de ce complexe (SSA1-SG1, SSA1-SG2, SSA1-SG1/2, SSA1-SG3, SSA2, SSA3, MED, MEAM1 et l’IO). Les abondances des populations d’aleurodes dénombrés sur manioc coïncident à des niveaux de type « pullulation » dans l’ensemble des zones échantillonnées, mettant en avant le statut de ces pays comme situés en zone épidémique. Ce travail de thèse a permis en outre de mettre en exergue le rôle de l’espèce SSA1-SG1 (P9H9/P18F5) dans la pullulation et l’expansion de la mosaïque africaine du manioc en Afrique centrale. Les populations de cette espèce et de cet haplotype en particulier ont été détectées comme dominantes et polyphages dans les pays échantillonnés. De même, au Cameroun, il été mis en avant que l’invasion et la pullulation de cet haplotype majoritaire pourrait être réalisé selon un processus d’invasion par hybridation avec les populations résidentes. Les données actuelles sur la distribution de cet haplotype dans ces deux pays tendent à montrer que non seulement le Cameroun et la RCA sont impactés par cette vague d’invasion mais pourraient l’être dans les pays limitrophes
The study of species and genetic richness of crops pest vector of plant viruses in a biological context of invasion in continental environment, is essential for understanding the mechanisms that underlay viral emergencies in sub-Saharan Africa. The cryptic Bemisia tabaci species complex is composed of many species, including the Sub-Saharan group of species that are subservient to cassava in Africa. They are directly involved in the vection of many viruses causing cassava mosaic disease (CMD) or the cassava brown streak diseases (CBSD). These diseases cause severe yield losses in cassava crops, which are among the leading starchy root crops in the African continent. Unfortunately very few studies on the vector of these diseases had been made in numerous African countries where the disease is of great concern. The diversity of whiteflies species on cassava in some countries remains broadly unknown. Furthermore, little information is available on the gene flow within species and between genetic subgroups recently described within these species. It is in this context that we conducted a genetic study on 898 samples from Central Africa and 667 samples from Cameroon using nuclear (microsatellites) and mitochondrial (COI) markers. These analyzes have allowed the characterization of the genetic variability at the intra- and inter-species level. The possible effect of factors such as the host plant and the geographical origin of analyzed individuals, often reported as genetic structuring factors in the species B. tabaci were also tested for (i) determining the nature of the species in circulation in these countries, (ii) understand the distribution of these populations, (iii) assess the extent of their diversity and genetic, structure, and (iii) consider the contribution of this knowledge in the management of whitefly populations in Central Africa. We were able to describe the presence of 6 species of B. tabaci complex and 5 subgroups of a species (SSA1) of this complex in CAR and Cameroon (SSA1-SG1, SG2-SSA1, SSA1- SG1 / 2, SSA1-SG3, SSA2, SSA3, MED, MEAM1 and IO). The abundances of whitefly populations on cassava coincide with levels of "outbreak" in all sampled areas, highlighting the status of these countries as in an epidemic area. This thesis has allowed also highlighting the role of the species SSA1 and its subgroup -SG1 with a specific haplotype P9H9 / P18F5 in the proliferation and expansion of the African cassava mosaic in Central Africa. Populations of this species and this particular haplotype were detected as dominant and polyphagous in sampled countries. Similarly, in Cameroon, it was emphasized that the invasion and overgrowth of this haplotype could be achieved through a process of invasion by hybridization with resident populations. Current data on the distribution of the dominant haplotype in both countries tend to show that not only the Cameroon and the CAR are affected by this wave of invasion but could be also in the neighboring countries