TY - JOUR

T1 - Whitefly control in cut gerbera

T2 - Is it possible to control Trialeurodes vaporariorum with Encarsia formosa?

AU - Berndt, Oliver

AU - Meyhöfer, Rainer

N1 - Funding information: Acknowledgments The presented experiments are part of a research project funded by the Federal Ministry of Nutrition, Agriculture and Consumer Protection, Germany.

PY - 2008/10

Y1 - 2008/10

N2 - We investigated the impact of inundative releases of the parasitoid, Encarsia formosa Gahan (Hymenoptera: Aphelinidae), for control of greenhouse whitefly, Trialeurodes vaporariorum (Westwood), on cut gerbera (Gerbera jamesonii L.) under controlled greenhouse conditions. Experimental units consisted of ten plants covered and separated from other units by gauze tents. We assessed three release rates of the aphelinid parasitoid: a 7-week experiment with a standard release rate (10 m-2/14 days), and a subsequent 3-month trial with high (100 m-2/week) and very high (1,000 m -2/week) release rates. Experimental units without release of parasitoids served as control treatment. Gerbera plants were infested initially with 50-100 juvenile and 50-70 adult whiteflies in the first experiment, and in the second experiment with less than 50 juveniles per plant and 50-70 adults. Whitefly and parasitoid population density were assessed in weekly intervals using infestation and activity categories. Results show that parasitized whiteflies were present in all treatments within 2 weeks after initial release. Unfortunately, it was not possible to control whiteflies with standard release rates of E. formosa. Although parasitism rates slightly increased, the effect on whitefly populations was negligible. Large amounts of honeydew and growth of sooty mold fungi caused the termination of the first experiment. In a second experiment, E. formosa was tested at 10-100 times higher release densities. In contrast to the first experiment, whitefly densities increased steadily during the first 8 weeks, but remained constant until the end of the experiment in both treatments. Parasitism by E. formosa reached its maximum after 8 weeks. We discuss possible reasons for the low efficiency of E. formosa as a whitefly antagonist in greenhouse production of gerbera.

AB - We investigated the impact of inundative releases of the parasitoid, Encarsia formosa Gahan (Hymenoptera: Aphelinidae), for control of greenhouse whitefly, Trialeurodes vaporariorum (Westwood), on cut gerbera (Gerbera jamesonii L.) under controlled greenhouse conditions. Experimental units consisted of ten plants covered and separated from other units by gauze tents. We assessed three release rates of the aphelinid parasitoid: a 7-week experiment with a standard release rate (10 m-2/14 days), and a subsequent 3-month trial with high (100 m-2/week) and very high (1,000 m -2/week) release rates. Experimental units without release of parasitoids served as control treatment. Gerbera plants were infested initially with 50-100 juvenile and 50-70 adult whiteflies in the first experiment, and in the second experiment with less than 50 juveniles per plant and 50-70 adults. Whitefly and parasitoid population density were assessed in weekly intervals using infestation and activity categories. Results show that parasitized whiteflies were present in all treatments within 2 weeks after initial release. Unfortunately, it was not possible to control whiteflies with standard release rates of E. formosa. Although parasitism rates slightly increased, the effect on whitefly populations was negligible. Large amounts of honeydew and growth of sooty mold fungi caused the termination of the first experiment. In a second experiment, E. formosa was tested at 10-100 times higher release densities. In contrast to the first experiment, whitefly densities increased steadily during the first 8 weeks, but remained constant until the end of the experiment in both treatments. Parasitism by E. formosa reached its maximum after 8 weeks. We discuss possible reasons for the low efficiency of E. formosa as a whitefly antagonist in greenhouse production of gerbera.

KW - Biological control

KW - Cut gerbera

KW - Encarsia formosa

KW - Gerbera jamesonii

KW - Trialeurodes vaporariorum

KW - Whitefly

UR - http://www.scopus.com/inward/record.url?scp=50249137834&partnerID=8YFLogxK

U2 - 10.1007/s10526-007-9123-z

DO - 10.1007/s10526-007-9123-z

M3 - Article

AN - SCOPUS:50249137834

VL - 53

SP - 751

EP - 762

JO - BIOCONTROL

JF - BIOCONTROL

SN - 1386-6141

IS - 5

ER -