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Title: INCIDENCE OF PARASITISM OF BEMISIA TABACI (HOMOPTERA: ALEYRODIDAE) IN THREE VEGTABLE CROPS AFTER APPLICATION OF BIORATIONAL INSECTICIDES

Author
item Simmons, Alvin
item ABD-RABOU, SHAABAN - GIZA, EGYPT

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2005
Publication Date: 10/1/2005
Citation: Simmons, A.M., Abd-Rabou, S. 2005. Incidence of parasitism of bemisia tabaci (homoptera: aleyrodidae) in three vegtable crops after application of biorational insecticides. J. Entomol Science. 40:474-477.

Interpretive Summary: Whiteflies are a big problem on row, vegetable, ornamental, orchard, and greenhouse crops. Instead of whitefly control with traditional insecticides, the use of natural compounds and low risk compounds may be compatible with the natural enemies of whiteflies. A field study was conducted to determine the effect of releases of a parasite, Encarsia sophia, on attack of the B-biotype sweetpotato whitefly in vegetable crops. Additional information was collected to determine the compatibility of six natural compounds and insect growth regulator (IGR) sprays on parasitism of the whitefly in vegetables. Weekly releases of the parasite were made over 15 wk in cabbage, cucumber, and eggplant. That resulted in an increase in attack on the whiteflies in all crops. Up to 70% of the whiteflies were parasitized in cabbage which was about 2-fold of the untreated check. The impacts on parasitism by the compounds were consistent among the three crops tested. The compounds were Biofly®, buprofezin (an IGR), jojoba oil, KZ oil, M-Pede®, and NeemAzal®. Regardless of concentration, parasitism was low (< than 5% by each of 2 parasite species) following treatment with either KZ oil or buprofezin, and remained low for 3 wk after the application. Parasitism was relatively high (~25-40% by each of two parasite species) for crops treated with either NeemAzal® or M-Pede® at the lowest concentrations. These results are useful in the development of improved whitefly management strategies.

Technical Abstract: A field study was conducted to determine the effect of inundative releases of Encarsia sophia (Girault Dodd) on parasitism of the B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius), in a vegetable cropping system, and the relative compatibility of six biorational compounds on parasitism. Weekly releases of E. sophia were made over 15 wk in cabbage (Brassica oleracea variety capitata L.), cucumber (Cucumis sativus L.), and eggplant (Solanum melongena L.). Weekly parasitism was enhanced in all three crops (averaging 31-46% per week) as compared with untreated controls where no releases were made (averaging 20-26% per week). Parasitism of up to 70% occurred following releases in cabbage which was about 2-fold of the untreated check. The impacts on parasitism by the compounds were consistent among the three crops tested. The compounds were sprayed on the crops at the rates of 0.5 to 1.5 ml/liter for Biofly®; 0.5 to 1 ml/liter for buprofezin; 5 to 15 ml/liter for jojoba oil and KZ oil each; 1.5 to 2.5 ml/liter for M-Pede®; and 2 to 3 ml/liter for NeemAzal®. Regardless of concentration, parasitism by either En. sophia or Eretmocerus mundus Mercet was low (< than 5% by each of 2 species) following treatment with either KZ oil or buprofezin (an insect growth regulator), and remained low for 3 wk after the application. Parasitism was relatively high (~25-40% by each of two species) for crops treated with either NeemAzal® or M-Pede® at the lowest concentrations. These results are useful in the development of improved whitefly management strategies.