Biological control ofBemisia argentifolii(Hemiptera: Aleyrodidae) on poinsettia with inundative releases ofEretmocerus eremicus(Hymenoptera: Aphelinidae): does varying the weekly release rate affect control?

Abstract

AbstractThe effectiveness of varying weekly release rates of the parasitoidEretmocerus eremicusRose & Zolnerowich for control ofBemisia argentifoliiBellows & Perring on poinsettias was determined. Two variable release rate strategies forE. eremicuswere evaluated: a low–high and a high–low release regimen. In the low–high treatment, one female parasitoid was released per plant per week for seven weeks, then the release rate was increased to five female parasitoids per plant per week for the remaining seven weeks of the trial. In the high–low treatment, five female parasitoids per plant per week were released for the first seven weeks, then the release rate was reduced to one female parasitoid per plant per week for the final seven weeks of the trial. Both release rates averaged three female parasitoids per plant per week. Life-tables were made forB. argentifoliiin the presence and absence of parasitoids. In the absence ofE. eremicus, egg to adult survivorship forB. argentifoliiwas 65%. In low–high release greenhouses, average egg to adult survivorship forB. argentifoliiwas 6% and parasitism was 28%. In high–low greenhouses, average egg to adult survivorship forB. argentifoliiwas 5% and parasitism was 16%. Average net reproductive rates forB. argentifoliiin the absence of parasitoids was 17 indicating a rapidly increasing population. Net reproductive rates were 1.46 and 1.24 for low–high and high–low release greenhouses, respectively, indicating substantially reducedB. argentifoliipopulation growth. At week 14 of the trial, densities of live nymphs and pupae were lower in high–low greenhouses when compared to low–high greenhouses. Better whitefly control is achieved with inundative releases ofE. eremicuswhen this natural enemy acts as a predator as opposed to a parasitoid.