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Project Leader(s): Paul A. Weston,
Senior Research Associate, Department of Entomology, Cornell University, Ithaca,
NY
Cooperator(s): Brian Eshenaur,
Horticulture Extension Educator, Monroe Co. Coop. Ext., Rochester, NY
Jana Lamboy, Ornamentals IPM Coordinator,
NYSAES, Geveva, NY
Type of grant: Biological
control and pest biology
Project location(s): Northeastern
U.S.
Abstract: The overall goal of this
project was to evaluate field efficacy of several bioloigical control agents
identified in the laboratory as having potential for biological control of viburnum
leaf beetle, a recently introduced pest in the U.S. Although the pest can be
controlled effectively with insecticides, biological control would be preferable
for long term management and for limiting pest damage to susceptible plants
in naturalized settings. We previously identified two generalist predators (Chrysoperla
carnea and Harmonia axyridis) and a pathogenic nematode (Heterorhabditis
bacteriophora) in laboratory trials that appear to have potential for controlling
viburnum leaf beetle; in this project we tested these organisms to the field
to see if their efficacy extended to this setting. In addition, we sampled soil
near host viburnums in the field for the presence of endemic nematodes. Both
species of predators significantly reduced the amount of damage sustained by
the caged viburnums compared to the control. In the case of H. axyridis,
the percent reduction was an impressive 75% or more. We were unable to ascertain
the efficacy of the nematode because adult emergence from the plots was too
low. Results from the soil sampling for nematodes was equivocal; the incidence
of nematodes was very low, perhaps because soil moisture was rather low compared
to 2000.
The results of this study indicate
that augmenting populations of predators with commercially available insects,
especially H. axyridis, may dramatically limit the amount of feeding
by viburnum leaf beetle larvae on susceptible viburnums (and likely reduce adult
populations by a similar extent since the larvae are being eliminated by the
predator). Pesticides needed for control of the pest would be correspondingly
decreased. Further evaluation is necessary, however, because the cages used
in this study may have resulted in greater predatory efficiency since the predators
were not able to leave the host plants. In addition, further field testing of
the nematode is needed to determine what their efficacy might be under more
typical conditions than those used in this study (e.g. utilizing ground covers
or mulch).
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