Abstract
AbstractThe effectiveness of inundative releases of the parasitoidEretmocerus eremicusn. sp. Rose & Zolnerowich for control ofBemisia argentifoliiBellows & Perring on poinsettia in replicated experimental greenhouses was determined. We evaluated two release rates ofE. eremicus:a low release rate (one female per plant per week, released in two greenhouses, in spring 1995) and a high release rate (three females per plant per week, released in two greenhouses, in spring 1994), each over a 14 week growing season. Each release trial had either one (1995) or two (1994) control greenhouses in whichB. argentifoliideveloped on poinsettia in the absence ofE. eremicus. Life-tables were constructed forB. argentifoliiin the presence and absence ofE. eremicusby using a photographic technique to follow cohorts of whiteflies on poinsettia leaves. Weekly population counts of whiteflies were also made. In the absence ofE. eremicus, egg to adult survivorship ofB. argentifoliion poinsettia was 75–81%. At the low release rate, egg to adult survivorship ofB. argentifoliiwas 12% and parasitism was 34%. At the high release rate, egg to adult survivorship ofB. argentifoliiwas 0.9% and parasitism was 10%. The average net reproductive rates (Ro) for populations ofB. argentifoliiin the absence ofE. eremicusranged from 20.5 to 26.1, indicating a rapidly increasing population density. Net reproductive rates for whitefly populations subject to parasitoid releases were 3.7 in the low release rate greenhouses, and 0.25 in the high release rate greenhouses, indicating substantially reducedB. argentifoliipopulation growth. At week 14 of the trial, densities of immature whiteflies were lower in greenhouses at the low release rate when compared to the high release rate greenhouses. This was attributed to high levels of in-house reproduction by parasitoids at the low release rate.
Published Version
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