Number Of Adult Whiteflies Research Articles

Comparative Field Evaluation of Auto-Rotate Gun Sprayer for Control of Bemisia tabaci in a Cotton Crop

Field evaluation of an auto-rotate gun sprayer and comparison with a knapsack sprayer was carried out to control whitefly Bemisia tabaci (Genn.) in the cotton crop. Two experiments were conducted at six locations of farmers' fields in southwestern (cotton-growing region) of Punjab state. The number of adult whiteflies was counted before and 3, 7 and 10 days after spray. Water-sensitive papers were attached at upper and under side of the leaves at three different points (top, middle and bottom) of plant canopy to find sprayers performance parameters, viz. droplet diameter, droplet density, per cent area covered and volume of spray deposition. Droplet density, area covered and volume of spray deposition were found significantly higher in case of the auto-rotate gun sprayer as compared to that of a knapsack sprayer. However, the volume median diameter of droplets was found significantly lesser in case of an auto-rotate gun sprayer, i.e. 286.95 µm as compared to the knapsack sprayer, i.e. 347.85 µm. The per cent whitefly control in the cotton crop in first experiment was found as 68.06 % and 65.90 % for auto-rotate gun and knapsack sprayer, respectively, by using pyriproxyfen 100 g active ingredient (g a.i.)/ha. Although in the second experiment the per cent whitefly control for auto-rotate gun sprayer was significantly higher, i.e. 83.27 % as compared to knapsack sprayer having 70.87 % control by using flonicamid 75 g a.i./ha. However, the bio-efficacy of auto-rotate gun sprayer was found higher for the both experiments as compared to the knapsack sprayer. The cost of operation of the auto-rotate gun sprayer was found to be US$4.11/ha as compared to knapsack sprayer with $6.85/ha. The cost, labour and time-saving in the spraying with the auto-rotate gun sprayer as compared to the knapsack sprayer was found to be 39.98, 93.44 and 96.64 %, respectively.

Control of Tomato leaf curl New Delhi virus in zucchini using the predatory mite Amblyseius swirskii

The tobacco whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), is a serious pest of vegetables in many horticulture systems. It vectors the Tomato leaf curl New Delhi virus (ToLCNDV) which causes considerable damage in zucchini crops. Both pest and the disease are well established in field and greenhouse crops in the southeast of Spain, the largest vegetable growing area in Europe. The predatory mite Amblyseius swirskii Athias-Henriot (Arachnida: Phytoseiidae) is known to effectively manage B. tabaci populations in crops such as sweet pepper and cucumber, feeding on eggs and crawlers of this pest. However, there are no reports on the effectiveness of predatory mites against tobacco whitefly in zucchini crops. The potential to reduce whitefly populations as well as the spread of ToLCNDV in zucchini was evaluated by the pre-installation of A. swirskii in seedlings. Results showed that the number of adult whiteflies and deposited eggs on zucchini plants were significantly lower on plants with the phytoseiid predator, showing a significant negative impact of A. swirskii on B. tabaci colonization and reproduction but not on the primary infection with ToLCNDV. However, the pre-release of the predatory mites resulted in a strong decrease in eggs and subsequently emerging adults of whiteflies relative to plants without predators, and a significant reduction in secondary spread of the virus.

A Primary Screening and Applying of Plant Volatiles as Repellents to Control Whitefly Bemisia tabaci (Gennadius) on Tomato.

With the goal of finding a new way to reduce population densities of Bemisia tabaci biotype Q in greenhouses, seven repellent volatile chemicals and their combinations were screened. The mixture of DLCO (D-limonene, citral and olive oil (63:7:30)) had a better cost performance(SC50 = 22.59 mg/ml)to repel whiteflies from settling than the other mixtures or single chemicals. In the greenhouse, in both the choice test and the no-choice tests, the number of adult whiteflies that settled on 1% DLCO-treated tomato plants was significantly lower than those settling on the control plants for the different exposure periods (P < 0.01). In the choice test, the egg amount on the treated tomato plants was significantly lower (P < 0.01) than that on the control plants, but there was no significant difference (P > 0.05) between the number of eggs on treated and control plants in the no-choice test. Compared with the controls, 1% DLCO did not cause significantly statistic mortality rates (P > 0.05) out of different living stages of B. tabaci. The tests for evaluating the repellent efficacy, showed that a slow-releasing bottle containing the mixture had a period of efficacy of 29 days, and the application of this mixture plus a yellow board used as a push-pull strategy in the greenhouse was also effective.

Effects of a Foliar Neem Formulation on Colonization and Mortality of Whiteflies (Hemiptera: Aleyrodidae) on Collard Plants

A study was conducted to determine the effects of foliar sprays of a selected neem (Azadirachta indica A. Juss) product (GOS Neem 7-Way) on colonization and development by the Middle-East Asia Minor-1 (= B-biotype sweetpotato whitefly) Bemisia tabaci (Gennadius) on collard (Brassica oleracea variety acephala de Condolle) plants. GOS Neem 7-Way is marketed for use as an insecticide in organic and conventional crop production. Caged choice, caged no-choice, and Y-tube olfactometer assays were conducted on oviposition, survival and adult behavioral response to plant treatment with 1.25% azadiractin. In the caged choice experiment, colonization by the whiteflies was reduced and fewer eggs were deposited on neem-treated plants as compared with control plants (only treated with an adjuvant). Similarly, decreased numbers of adult whiteflies and reduced whitefly development were observed in no-choice assays for the neem-treatment, as compared with the untreated control. Both horizontal and vertical-orientated Y-tube olfactometer assays provided complementarily assessments that the neem had a repellency effect on the adult whiteflies. However, the repellency effect primarily dissipated within one day post treatment. Overall, the greatest benefit of the neem treatment appears to have been on whitefly mortality. The findings may be useful in providing a more ecologically sound way to manage populations of the B. tabaci whitefly in organic vegetable production.

Screening of Some Foliar Chemical Insecticides against White Fly (&lt;i&gt;Bemisia tabaci&lt;/i&gt;) on Tomato at Metema District, North Gondar, Ethiopia

Tomato is one of the vegetable crops growing in Ethiopia and important cash crops for small scale growers with a potential for increasing incomes in rural areas, improving the living standards and creating employment opportunities for women and youth. Vegetables in tropical countries are the crops which are often attacked most seriously by arthropod pests. Among the major insect pests, white flies, one of a serious leaf-sucking pest, cause direct damage to plants by sucking plant sap. The experiment was conducted in farmer’s field with supplementary irrigation at Aftete-Kumer locality in Metema District since 2011/12 to select effective foliar insecticide for white fly control. The experiment was initiated with 5 treatments such as 4 foliar insecticides and control. Foliar chemical insecticides such as Ethiosulfan 35% EC, Ethiothoate 40% EC, Ethiolathion 50% EC and Metasystox 250% EC were used with rate of 2, 1.5, 1.5 and 0.9 milliliter per plot respectively and arranged by using RCBD with three replications. Melka shola tomato variety was used in this study. Post spray count was carried out three times at 2, 5 and 7 days after applying the insecticides. All data were analyzed by using SAS computer software. Plots sprayed with Ethiothoate and Ethiolathion showed less significant difference on stand counting at harvesting with mean number of plants of 48.3 and 41.6 per plot respectively as compared to plots sprayed with Ethiosulfan (39.60), Metasystox (37.6) and Control (37). All treatments were not shown significant difference on pre-spraying count of adult white flies. In case of post-spray count of adult white flies, Ethiothoate showed highly significant difference (p < 0.05) with least number of white flies population (1.6 per leaf) followed by Ethiolathion (2 per leaf). The highest number of adult white flies was recorded from control (25) and Metasystox (16.6) followed by Ethiosulfan (14.3). Regarding yield, there was significant difference (p < 0.05) between treatments. The highest yield was obtained from Ethiothoate (401.6 grams per plot) and Ethiolathion (356.67 grams per plot) followed by Metasystox (119.6 grams per plot) and Ethiosulfan (113.3 grams per plot). The lower yield was obtained from control (81.6 grams per plot). Ethiothoate and Ethiolathion have shown highest efficacy in controlling tomato white fly through reducing the population.

PRELIMINARY STUDY OF RESISTANCE AGAINST BEMISIA TABACI GENN. IN TGR-1551 MELON GENOTYPE

The Zimbabwean genotype TGR-1551 had been found to be resistant to Bemisia tabaci Genn. in previous studies. In order to have a better knowledge of this resistance and determine the most suitable character to evaluate the genetic resistance to B. tabaci, three whitefly life-parameters have been tested in a RIL population (F 7 ) derived from a cross between 'TGR-1551' and the susceptible Spanish cultivar 'Bola de Oro'. Plants of each parent, their F 1 and 62 RIL were grown in a greenhouse under natural conditions of whitefly infestation. In each plant, the number of adults of B. tabaci, ovoposition and number of empty pupal cases were recorded. Significant differences were found between parents for each whitefly life-parameter: TGR-1551 showed a high level of resistance whatever the parameter was considered, and 'Bola de Oro' behaved as highly susceptible to B. tabaci. The low number of adults and low ovoposition found on leaves of TGR-1551 suggested the presence of non-preference mechanisms in this genotype. In the F 1 population, the number of adult whiteflies and the ovoposition was similar to 'Bola de Oro', while the number of empty pupal cases was similar to the number found in TGR-1551. These results pointed to the existence of antibiotic mechanisms in the resistant genotype which impede B. tabaci to reach its adult stage. Highly significant differences among RIL were observed for the three parameters, mainly for the number of empty pupal cases, explaining the 43 % of the variance observed. Some RIL behaved like TGR-1551 and some like the F 1 , which suggested a different genetic control of antixenosis and antibiosis mechanisms in TGR-1551. Dominance effects seem to be involved in antibiosis, while antixenosis, measured as ovoposition, should be regulated by recessive factors. These results confirm the usefulness of the number of empty pupal cases in the selection of B. tabaci resistance and for genetic studies.

Effect of Pongam oil on Adults of the Greenhouse whitefly Trialeurodes vaporariorum (Homoptera: Trialeurodidae)

The aim of this study was to test the effects of pongam oil from the Indian beech tree, Pongamia pinnata (Linnaeus) Pierre, on whiteflies (Trialeurodes vaporariorum Westwood 1856). Three experiments were conducted on chrysanthemum plants: (a) a choice test with treated and untreated plants; (b) a no-choice test; and (c), direct treatments on adult whiteflies on plants. All experiments were run under greenhouse conditions in insect proof-cages. The choice and no-choice test were evaluated after the 4 th , 8 th and 12 th day after the treatment with different concentrations of pongam oil suspension (2.0%, 1.0% and 0.5%). The number of adult whiteflies and the number of eggs per leaf were evaluated. Pongam oil treatments reduced both, the number of adult whiteflies and eggs on the chrysanthemum plants. Generally, this effect declined over time and was weaker for the lower than for the higher concentrations. Pongam oil may be considered as a promising preparation for greenhouse plant protection.

Current characteristics of cassava mosaic disease in postepidemic areas increase the range of possible management options

AbstractAs a case study to document the current characteristics of cassava mosaic virus disease (CMD) in postepidemic areas, surveys were carried out, in 2003 and 2004, in Siaya District of western Kenya. This was an area affected by a severe CMD pandemic in the late 1990s. Data recorded on cassava varieties were CMD incidence, severity index and number of adult whiteflies. Farmers (174) were interviewed on their understanding of the disease and their knowledge and practice of management interventions. Cassava cultivation was being re‐established, but local landraces predominated. Resistant varieties were present 13% in 2003, and 4% in 2004, of the surveyed fields. Adhiambolera was the most common variety, occurring in 35% and 40% of fields in 2003 and 2004, respectively, and had an average CMD incidence of 82% in 2003 and 73% in 2004. By contrast, the CMD‐resistant variety Migyera had a low mean incidence (28% in 2003). The overall incidence for both years was 71%, consisting of 61% as a result of infection through planting diseased cuttings and 10% as a result of whitefly infection. In 2003, the total incidence was 72% and the average severity 2.7 (severity index), while in 2004 the incidence was 78% and the severity 2.6. There were significant severity variations in each division of the Siaya District during the 2 years except for Karemo and Ukwala. The abundance of whiteflies on the top five leaves of plants was low in 2003 but high in 2004, with means of 1 and 16, respectively, over the same seven divisions in both years, although this variation was thought to be because of seasonal factors. East African cassava mosaic virus‐Uganda was the predominant geminivirus present in every division. Phytosanitation by farmers was minimal, as evidenced by 29% of farmers using a selection of CMD‐free stems for planting and 15% using hand‐roguing for CMD management. Occurrence of more than 25% CMD‐free plants in 2004, moderate CMD severity and limited spread provide a conducive environment for the use of phytosanitation as a CMD control measure that can be immediately used by farmers growing their own cassava varieties.

Examination of the Biological Effects of High Anionic Peroxidase Production in Tobacco Plants Grown under Field Conditions. I. Insect Pest Damage

At least 25 wild type and high peroxidase tobacco Nicotiana tabacum L. plants were examined semiweekly over several weeks for pest insect distribution and damage in a 2 year field study. Incidence and/or severity of naturally occurring caterpillar damage (dingy cutworm (Feltia ducens Walker), black cutworm (Agrotis ipsilon (Hufnagel), tobacco hornworm (Manduca sexta L.), and false tobacco budworm (= corn earworm Helicoverpa zea (Boddie)) was significantly reduced at several sample dates for high peroxidase vs. wild type plants. These results parallel those of prior laboratory studies with caterpillars. The number of adult whiteflies (Trialeurodes vaporariorum (Westwood) per plant was significantly reduced on high peroxidase compared to wild type plants on most sample dates in both years. The number of plants with leaves containing >100 aphids (primarily Myzus persicae Sulzer) per leaf on high peroxidase plants was significantly lower that on wild type plants after an equivalent invasion period in both years. A significantly higher proportion of aphids were found dead on leaf five of high peroxidase compared to wild type plants at most sample dates in both years. These results indicate that high peroxidase plants have resistance to a wide range of insects, implicating this enzyme as a broad range resistance mechanism.

Estimation of the Number of Adult Whiteflies in Emergence Cages Based on Volume and Weight of Samples

Estimation of the Number of Adult Whiteflies in Emergence Cages Based on Volume and Weight of Samples

Transmission of an Indonesian Isolate of Tobacco leaf curl virus (Geminivirus) by Bemisia tabaci Genn. (Hemiptera: Aleyrodidae)

Bemisia tabaci Genn. is an important pest worldwide because of its ability to cause damage by direct feeding and its role as a vector of some viruses including geminiviruses. The first report of Tobacco leaf curl virus (TLCV), a Geminiviruses, in Indonesia was in 1932 when the virus was found infecting tobacco plants in Central Java. The characteristic symptoms of TLCV included upward curling of the leaf edge, vein thickening, and sometimes the occurrence of enation on the underside of the leaves. Basic studies were carried out to elucidate the characteristics of TLCV transmission by its vector, B. tabaci. A single whitefly was able to transmit the virus and the efficiency of transmission was increased when the number of adult whiteflies was increased up to 20 per plant. Inoculation access period of 1 h could cause transmission up to 20% and the optimum inoculation access period was 12 h. Acquisition access period of 30 minutes resulted in 70% transmission while 1(10% transmission occurred with a 24-h acqui-sition access period. The virus was proven to be persistently but not transovarially transmitted. Discrete fragments of 1.6 kb were observed when polymerase chain reaction method was applied to detect the virus in viruliferous nymphs and individual adults of B. tabaci, while no bands were obtained from non-viruliferous nymphs and adults.

Phytoseiid predators suppress populations of Bemisia tabaci on cucumber plants with alternative food.

Phytoseiids are known to attack whiteflies, but it is an open question whether they can be used for biological control of these pest insects. Preselection experiments in the laboratory showed that two out of five phytoseiid species tested, Euseius scutalis and Typhlodromips swirskii, stood out in terms of their ability to develop and reproduce on a diet of Bemisia tabaci immatures. In this paper, we show that both predators are able to suppress whitefly populations on isolated cucumber plants in a greenhouse. Predatory mites were released 2 weeks in advance of the release of B. tabaci. To enable their survival and promote their population growth, they were provided weekly with alternative food, that is, Typha sp. pollen. A few weeks after whitefly introduction, the numbers of adult whiteflies on plants with predators were consistently lower than on plants without predators, where B. tabaci populations grew exponentially. After 9 weeks, this amounted to a 16- to 21-fold difference in adult whitefly population size. This shows that the two phytoseiid species are promising biocontrol agents of B. tabaci on greenhouse cucumber.

Control of Silverleaf Whitefly and Tomato Pinworm on Staked Tomato with Chemical and Biological Insecticides, Spring 1994

Abstract Beds (32 inch width) were prepared in sandy soil on six foot centers, fumigated with a 67/33% mixture of methyl bromide and chloropicrin applied at 220 lbs/acre, fertilized with a bottom mix of 800 lbs/acre of 5-16-8 and a top mix of 500 lbs of 19-0-30 and mulched with whiteface polyethylene film. Greenhouse grown tomato seedlings were transplanted 18 inches apart on 1 Mar 1994 into single rows and watered by subsurface seepage irrigation. Plants were sprayed weekly with 3.0 lb/acre Kocide DF plus 1.0 lb/acre Maneb 80W rotated with Bravo 720 applied at 32 oz/acre. Standard cultural practices of pruning and staking were followed. There were 12 rows 240 foot long divided into 4 replicated blocks of 3 rows each. Each block consisted of 10 treatments assigned in a completely randomized design. An adjuvant, ASPA 80, was added to each spray mixture at the rate of 0.06% v/v except for RH-0345 to which Latron-B-1956 was added at 0.06% v/v. Plants were sprayed weekly except for Biobit alone which was sprayed twice a week at 0.5 lb product/acre. Applications were made with a tractor-drawn hydraulic boom sprayer using a diaphragm pump at 200 psi through two drop lines per row fitted with Albuz@ ATR Yellow nozzles. Spray treatments commenced 29 Mar and continued through 10 May for a total of 7 weeks. Initial spray volume was 46 gal/acre increasing to 65 gal/acre on 5 April and finally to 83 gal/acre 3 May corresponding to the increases in number of nozzles from 2 to 3 to 4 per drop respectively. Plants were evaluated weekly for the presence of whitefly adults, eggs, nymphs, pupae, and parasitized pupae. Relative estimates of adult whitefly numbers were made by striking a black, 9.5” × 13” pie pan coated with an oil/detergent mixture against three plants from each row in every plot and recording the number of adult whiteflies caught. Egg populations were estimated from randomly sampled first expanded trifoliates, one per row (3 per plot). Eggs in 4 cm2 of leaflet were counted with a stereoscopic microscope by placing a 1 cm2 template twice on each side of the midvein. Nymphs were counted in the same way except that the trifoliate sampled came from the 5th, 6th or 7th node from the top. All plants were inspected weekly for symptoms of tomato mottle geminivirus (TMoV), the presence of which was confirmed by nuclear inclusion analysis. On 19 May, all fruit of marketable size was harvested from the best 10 plants per plot. Fruit was culled based on damage from tomato pinworm, other insects, or non-insect causes. Marketable tomatoes were sized to USDA standards on a commercial grading table.

Control on Fall Squash, 1987:

Abstract A pesticide efficacy trial was conducted at the University of Arizona Valley Experiment Station in Yuma to evaluate the ability of various insecticides to control the sweetpotato whitefly on squash. Plots were planted 25 Sept. Experimental materials were compared with untreated control plots and Thiodan 3 EC. A completely randomized design was used with 4 plots receiving each treatment. Plots measuring 6 by 2 m were separated by 22.25 m along the rows and 33.3 m across the rows. Test materials were applied 27 Oct using a CO2-pressurized backpack sprayer at a pressure of 206.8 kPa and a rate of 83.3 liter/hectare. Three sampling methods were used to record the number of adult whiteflies: In the leaf counts 10 leaves from each plot were examined; in vacuum samples, whiteflies were collected using a hand vacuum for a period of 5 s/plot; sticky card trap was placed in each plot from 10 am to 11 am. The leaf count sampling was the only method to show separation between the treatment means, so these are the only data presented here.

Bayberry Whitefly Control on Lemons, 1981

Abstract Plots were located in Irvine, and were three rows of trees; evaluations came from the middle row. Tree spacing was 12 by 22 ft. Experimental design was completely randomized. Treatments were evaluated by counting the number of adult whiteflies on five terminals from each of eight trees per plot. All treatments except the Imidan/Lannate treatment included 2.5 gal/acre NR 415 oil.

Bayberry Whitefly Control on Lemons, 1981

Abstract Plots were located in Corona, Calif., and were three rows of trees; evaluations came from the middle row. Tree spacing was 20 by 20 ft. Experimental design was completely randomized. Each treatment was evaluated by counting the number of adult whiteflies from 80 (10 per tree; 8 trees) young growing shoots (terminals) which are the whitefly’s preferred feeding and oviposition sites.

Bayberry Whitefly Control on Lemons, 1982

Abstract Plots were located in Irvine, Calif, and were three rows of trees; evaluations came from the middle row. Tree spacing was 14 by 22 ft. Experimental design was randomized block with three blocks. Trees were short (ca. 12 ft) and there was considerable overlap in the spray pattern from 2.5 to 5.5 ft above ground. Each treatment was evaluated by counting the number of adult whiteflies on eight terminals from each of five trees per plot. This test also evaluated the rates of Pounce as well as the inclusion of oil or Citrufilm (Helena Chemical Co., Memphis, Tenn.) and the transformed data (logx+1) were analysed by two-way analysis of variance (ANOVA) and Duncan’s multiple range test. Three unsprayed control plots were included in the experiment but not in the randomized complete block. They were located 10 rows away from the main experiment to prevent them from becoming a source of reinfestation to any of the insecticide treated plots and to avoid the effect of insecticide drift into the unsprayed plots. The precount, based on pooling samples from 826 terminals on 18 and 20 Oct. was 13.3 adults per terminal. At the time of the test, the whitefly adult population was in a period of natural decline so that by 7 weeks after insecticide application the unsprayed plots had the lowest populations. It is not certain if the cause of this decline was biological control, weather or some other factor(s). Significant interactions in ANOVA of the main effects confused the analysis on all but the 22 Nov. data so the data were evaluated by plotting the mean and standard error of each plot.

Bayberry Whitefly Control on Lemons, 1982

Abstract Plots were located in Irvin, Calif., and were three rows of trees; evaluations came from the middle row. Tree spacing was 14 by 22 ft. Experimental design was completely randomized. Each treatment was evaluated by counting the number of adult whiteflies (from on five terminals from each of eight trees per plot.) This test was split into two parts: (1) evaluation of several compounds for whitefly control (Table 1 and 2); evaluation of Pounce at different rates and with different additives (Table 2).