Number Of Whiteflies Research Articles

Dispersion patterns, sample unit-sizes and techniques for sampling cotton jassid [ Amrasca biguttula biguttula (Ishida)] and whitefly ( Bemisia tabaci, Genn.)

Spatial dispersion of the nymphs of the jassid, Amrasca biguttula biguttula (Ishida), and the adults of the whitefly, Bemisia tabaci Genn. on F414, a Gossypium hirsutum variety, was systematic in Ludhiana (Punjab). Both the jassid and the whitefly displayed no definite pattern along the height of the plant, though a maximum number of whiteflies were recorded at middle canopy (21–40 cm from bottom). Sample sizes of 10–15 plants, selected in a statistically linear fashion represented populations of jassid nymphs and adult whitefly on all four varieties. Sampling jassid nymphs by visual counting and whitefly by split-cage were the most suitable sampling methods for local cotton growers among the various methods compared.

Field studies on the spread of African cassava mosaic

SUMMARYThe spread of African cassava mosaic disease (ACMV) into healthy cassava fields was recorded at weekly intervals. In addition, 21 yellow water traps were placed in one field and the number of whiteflies caught was recorded twice a week. The number of Bemisia spp. feeding on cassava was also estimated. The results indicate that the pattern of disease spread is related to the pattern of infestation with Bemisia.Airborne whiteflies carried by the south‐west prevailing wind alighted preferentially on cassava plants along the upwind edges (south and west borders) of the plantings. The pattern of incidence of mosaic disease resembled that of whiteflies. Along the SW‐NE diagonal, there was a gradient of disease incidence with a maximum at the SW corner block. Similar gradients occurred in three different fields and they were maintained throughout the 6‐month study, although gradually flattening with time. There were indications that the reservoirs both of the virus and of the vectors were located some distance upwind from the experimental fields.

Whiteflies Population and its Impact on the Incidence of Tomato Yellow Mosaic Virus in Venezuela

AbstractThe heavy incidence of Tomato Yellow Mosaic Virus in Venezuela is related to the high population densities of its vector, the whitefly Bemisia tabaci Genn. The main factor affecting the population of the vector is the rainfall pattern; during the rainy season the populations are low but they increase rapidly in the drier months. A good correlation was found between the number of whiteflies trapped and the incidence of infested plants. It seems that in the low laying areas of the tropics the temperature does not have a marked effect on the whitefly population since it remains quite stable throughout the year.

Greenhouse whitefly control through the combined use of the colour attraction system with the parasite waspEncarsia formosa [Hym.: Aphelinidae

The combined use of colour attraction (yellow sticky plates) andEncarsia formosa (Gahan) parasites reduced the greenhouse whiteflyTrialeurodes vaporariorum (Westwood) population in a spring tomato crop to an extremely low level. Whiteflies were strongly attracted to yellow sticky plates while the parasite,E. formosa, was not attracted so long as suitable and sufficient hosts were present. As the numbers of whiteflies declined, parasites were increasingly trapped by the plates. The percent parasitization increased continuously during the experiment, reaching about 90%, indicating the complete compatibility of colour attraction and biological control.

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).

Influence of Five Gossypium Species Cytoplasms on Yield, Yield Components, Fiber Properties, and Insect Resistance in Upland Cotton1

The influence of five exotic cotton (Gossypium spp.) cytoplasms on yield, yield components, fiber properties, and insect populations was determined at Stoneville, Miss. The five cytoplasms were G. herbaceum L., G. arboreum L., G. anomalum Wawra ex Wawra & Peyr., G. barbadense L., and G. tomentosum Nutt. ex Seem. The five cytoplasms were combined by repeated backcrossing into the following upland cotton (G. hirsutum L.) cultivars: ‘B3080’, ‘Coker 201’, ‘Delcot 277’, ‘Deltapine 16’, and ‘Stoneville 213’. The average number of backcrosses into G. hirsutum was 10.1 and into the specific cultivars, 6.5.The characteristic most influenced by exotic cytoplasms was yield. Cytoplasm from G. arboreum decreased yield I8%, averaged for all cultivars. Exotic cytoplasms in general decreased yields, but this trend was not consistent for all cultivars. The average 1977 decrease in yield was 80, 61, 41, 17, and −5 kg/ha for Deltapine 16, Coker 201, Stoneville 213, B3080 and Delcot 277, respectively. The foreign cytoplasms had no strong deleterious effects on yield components and fiber properties.No evidence of variations in tolerance to tarnished plant bugs (Lygus lineolaris Palisot de Beauvois) was detected in the 1977 study. In 1978 no differences due to cytoplasms were detected in numbers of tarnished plant bugs and white flies (Trialeurodes abutilonea Haldeman). However, the AD3 (G. tomentosum) cytoplasm resulted in a 70% increase in numbers of leafhoppers (primarily Empoasca spp.) and a 35% decrease in weights of 7‐day old larvae of tobacco budworm (Heliothis virescens F.).The interaction of some nuclear genes and exotic cytoplasms was compatible for yield and significant for some pest damage. This result suggests that a back‐up cytoplasmic system could be developed to help reduce the danger of major ephiphytoties or damage by insects.

Effects of season, sowing date, nitrogenous fertilizer and insecticide spraying on the incidence of insect pests on cotton in the Sudan Gezira

SUMMARYThe effects of the sowing date of cotton and application of nitrogenous fertilizer to it on the incidence of insect pests were investigated over a 5-year period. Response to frequent insecticide spraying was also determined and the results were related to previously reported interactions between nitrogen, sowing date and insecticide application in their effects on yield and its year-to-year variation. Numbers of jassids (Empoasca lybica de Berg) and whiteflies (Bemisia tabaci Genn) were considerably greater on the fertilized plots. The pattern of pest population change over the season varied with sowing date and also from year to year as did the relative numbers of jassids and whiteflies. Effects of spraying on the yield obtained under different agronomic treatments and in different years were clearly related to effects on numbers of insect pests.

Control of the Mexican Fruit Fly by Bait Sprays Concentrated at Discrete Locations12

when a bait spray (a 1:4 mixture of 95% technical malathion and an acid hydrolysate of corn protein) was repealedly applied to small portions of navel orange trees in an orchard in Coatepec, Veracruz, Mexico, the number of adult Anastrepha ludens (Loew) trapped in the treated area was 85-98% less than the number trapped in the check area, even though reinfestation from surrounding untreated groves was probably constant. Also, the number of larvae-per-kilo was reduced as much as 84% in tree fruit and slightly more in fallen fruit. The fruit produced in the treated areas was of local market quality except at the spring peak of the population of the flies and probably could have been exported after fumigation. The increase in the numbers of whiteflies, probably cloudy-winged whiteflies, Dialeurodes citrifolii (Morgan), in the treated area may be attributable to the increased mortality of green lacewings, chrysopa sp.

Bionomics of the Whitefly-Parasite Complex Associated with Cotton in Southern California (Homoptera: Aleurodidae; Hymenoptera: Aphelinidae)

Bionomics of the Whitefly-Parasite Complex Associated with Cotton in Southern California (Homoptera: Aleurodidae; Hymenoptera: Aphelinidae)