Seasonal Abundance and Within-Plant Distribution of Parasitoids of Bemisia tabaci (Homoptera: Aleyrodidae) in Peanuts

1993 ◽  
Vol 22 (5) ◽  
pp. 1043-1050 ◽  
Author(s):  
Heather J. McAuslane ◽  
Fred A. Johnson ◽  
David A. Knauft ◽  
Daniel L. Colvin
Keyword(s):  
Bemisia Tabaci ◽  
Plant Distribution ◽  
Seasonal Abundance

Infestation of Germplasm Lines and Cultivars of Cotton in Arizona by Whitefly Nymphs (Homoptera: Aleyrodidae)

1990 ◽  
Vol 25 (2) ◽  
pp. 223-229 ◽  
Author(s):  
H. M. Flint ◽  
N. J. Parks
Keyword(s):  
Gossypium Hirsutum ◽  
Bemisia Tabaci ◽  
Seasonal Abundance ◽  
Sweetpotato Whitefly ◽  
Gossypium Hirsutum L ◽  
Consistent Effect ◽  
Leaf Trichomes ◽  
Trialeurodes Abutilonea ◽  
Field Plots

Seasonal abundance of whitefly nymphs, primarily sweetpotato whitefly, Bemisia tabaci (Gennadius), and bandedwinged whitefly, Trialeurodes abutilonea (Haldeman), on leaves of germplasm lines and cultivars of cotton, Gossypium hirsutum L., were determined in field plots at Maricopa, AZ, in 1987. In general, the germplasm lines with the greatest numbers of leaf trichomes (range 2 to 98 per cm2) had the greatest numbers of nymphs (range 0.4 to 11.3 nymphs per leaf on 23 September). The okra-leaf characteristic did not have a consistent effect on the numbers of nymphs. Deltapine 20, Centennial, and Stoneville 506 cultivars planted on 30 April had significantly greater infestations (range 20.3 to 121.3 nymphs per leaf) on 16 October than did the same cultivars planted 21 May (range 4.5 to 53.0) or 11 June (range 7.0 to 31.5). The nectariless okra-leaf line WC-12NL and cultivar Deltapine 61 had 1.1 and 1.5 nymphs per leaf on 22 September, respectively, not significantly different.

scholarly journals Distribution Pattern of Sweet Potato Whitefly Bemisia tabaci (Gennadius) on Tomato Plants

1997 ◽  
Vol 2 ◽  
pp. 43
Author(s):  
K.M. Azam ◽  
S.A. Razvi ◽  
M.H. AI-Muhthuri ◽  
A.A. AI-Raeesi
Keyword(s):  
Bemisia Tabaci ◽  
Sharp Decrease ◽  
Plant Distribution ◽  
Tomato Plants ◽  
Ovipositional Preference ◽  
Dispersion Patterns ◽  
Egg Density ◽  
Middle Strata ◽  
Lower Plant ◽  
Temporal Dispersion

A field experiment was conducted to study the intra plant distribution and temporal dispersion patterns of whitetly (Bemisia tabaci Gennadius) eggs and nymphs on tomato plants to establish a sampling method which would give accurate estimates of the population size. From the third week to the ninth week after transplanting, terminal leaflets were collected from the outer and inner canopies of each of the upper, middle, and lower plant strata. A strong ovipositional preference was found in whitefly adults at an early crop age. A maximum of 50.6% of the eggs were deposited in the middle stratum followed by upper (36. 15%) and lower strata (13.3%). However, most of the nymphs (65.5%) were present in the lower stratum followed by middle (32.4%) and upper strata (2. l %). These findings indicated that when taking observations in egg counts the most preferred site is the upper and middle strata while for nymphal counts it is the lower and middle strata. There was a sharp decrease in egg and nymphal counts from the seventh week after transplantation which clearly indicated that, after this age , the corp is not preferred by whitefly . Egg and nymphal population of whitefly on tomato plants in the field were distributed in aggregates as evident by high variance to mean ratio. Values ranged from 2.72 to 14.36 and 4.52 to 21.82 for egg counts and nymphal population, respectively.  Aggregation of whitefly eggs and nymphs in all cases might be due to the behavior of adults to congregate and to the heterogeneity of the environment . The appropriate number of leaflets required for the estimation of egg density at 10% and 20% error was found to be 149 and 37, respectively. In the case of nymphal population the numbers were 163 and 41 at 10% and 20% error, respectively.

Seasonal abundance and distribution of Tetranychus urticae (Acari: Tetranychidae), the two spotted spider mite, on cotton in Australia and implications for management

1993 ◽  
Vol 83 (2) ◽  
pp. 291-303 ◽  
Author(s):  
L.J Wilson ◽  
R Morton
Keyword(s):  
Pest Management ◽  
Tetranychus Urticae ◽  
Spider Mite ◽  
Seedling Emergence ◽  
Sampling Technique ◽  
External Source ◽  
Plant Distribution ◽  
Seasonal Abundance ◽  
Simple Sampling ◽  
Two Spotted Spider Mite

AbstractThe two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a pest of cotton in Australia yet has received little attention. To develop sampling strategies for pest management the seasonal abundance and intra-crop distribution of T. urticae on cotton was studied. T. urticae colonized cotton crops at seedling emergence in October. Populations declined through November/December then increased progressively thereafter, at varying times and rates. Higher initial infestation levels were correlated with earlier, potentially more damaging, mite outbreaks. Survival of T. urticae through November/December appears crucial in determining the extent to which this potential is realized. Nodes 3 to 5 below the terminal were most heavily infested and should be used as the sampling unit for mites. The within plant distribution of T. urticae was unaffected by cotton variety or insecticide applications. T. urticae was more abundant on the edges of fields than in the interior early in the season (October and November) indicating colonization from an external source. The edge effect diminished with time, suggesting a lack of continuous colonization. The only exceptions to this pattern occurred when T. urticae migrated from senescent maize crops into the nearby cotton crops in early January. A simple sampling technique, based on the presence or absence of mites on leaves was developed for pest management purposes.

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