Foraging behaviour and mutual interference of Encarsia formosa Gahan parasitizing greenhouse whitefly, Trialeurodes vaporariorum Westwood

Author(s):  
A. Walia ◽  
S. C. Verma ◽  
P. L. Sharma ◽  
R. S. Chandel ◽  
S. Palial ◽  
...  
1967 ◽  
Vol 45 (4) ◽  
pp. 539-578 ◽  
Author(s):  
T. Burnett

Three populations of the greenhouse whitefly, Trialeurodes vaporariorum, and its chalcid parasite Encarsia formosa were propagated each year for three consecutive years on tomato plants in the greenhouse. The abundance of the host and parasite species fluctuated either with peaks of increasing amplitude, with peaks of decreasing amplitude, or with irregular peaks. The dominant process in the interaction was the occurrence of two qualitatively different types of host larval mortality: (a) parasitization, and (b) almost immediate killing after attack by adult parasites. Fluctuations in host and parasite abundance resulted from the almost immediate killing of small host larvae and the death of the short-lived adult parasites. The parasite population tended to destroy similar percentages of host populations of different densities but host mortality was also related to the age structure of the host population. Variation in host reproduction, caused by differences in rearing temperature and by seasonal variation in the physical environment, influenced host and parasite densities.


1992 ◽  
Vol 2 (4) ◽  
pp. 457-460 ◽  
Author(s):  
R.W. McMahon ◽  
R.K. Lindquist ◽  
M.L. Casey ◽  
A.C. Witt ◽  
S.H. Kinnamon

A demonstration study was conducted to compare the effectiveness of biological and chemical control treatments on the greenhouse whitefly (GHWF) (Trialeurodes vaporariorum, Westwood) using poinsettia (Euphorbia pulcherrima Wild.) stock plants. Two identical greenhouse compartments, each containing 84 stock plants, were used. In the biological control compartment, three biweekly releases of Encarsia formosa (EF) were made, while in the chemical control compartment eight weekly applications of resmethrin or acephate aerosol treatments were made. Results showed that overall greenhouse whitefly populations in the chemical control compartment were slightly lower than in the biological control compartment. Cuttings taken from stock plants in the biological control compartment at the end of the experiment were commercially acceptable with regard to the presence of GHWF adults. Chemical names used: O,S-dimethyl acetylphosphoramidothioate (acephate), [5-(phenylmethyl)-3-furanyl] methyl 2,2-dimethyl-3-(2-methyl-1-propenyl)cyclopropane-carboxylate (resmethrin).


1974 ◽  
Vol 106 (11) ◽  
pp. 1175-1188 ◽  
Author(s):  
Robert G. Helgesen ◽  
Maurice J. Tauber

AbstractParasitized and unparasitized whitefly populations were sampled on a short-term crop (poinsettia) at 4–7 day intervals until crop harvest. Age-specific whitefly survivorship and parasite activity were evaluated in relation to various biotic and abiotic factors. Three critical factors influenced the outcome of the whitefly–Encarsia formosa interaction during short-term crop production. Commercially acceptable levels of control were achieved on poinsettia by (a) introducing parasites during the first 40 days of crop production, as pupae, when small scales were abundant, (b) introducing sufficient parasite pupae to develop a ratio of one adult parasite for every 30 large whitefly scales, and (c) maintaining an average temperature of 23.3 °C (74°F).


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