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Volunteer
Research on
Alternative IPM Tactics
in Home Gardens and Landscapes
Robert
N. Wiedenmann
Illinois Natural History Survey
Clifford
S. Sadof & Robert J. O'Neil
Purdue University
Beginnings
Pesticide use in home lawns and gardens, per-acre, exceeds that of crops.
Home gardeners want to replace pesticides with biologically based tactics,
and could reduce pesticide use dramatically, but are unaware of alternatives
or how to use them.
Two pilot workshops on biological control for Master Gardeners were offered
to 70 Gardeners in 1996. These two pilot workshops led to the development
of a USDA North Central IPM funded project allowing expanded training
and volunteer research projects.
Workshops and Research 1998-99
We developed a training and volunteer research program for Indiana and
Illinois gardeners, to teach and test biological control options, using
the gardeners’ ideas and their gardens as test plots. In 1998 and
1999, we taught 180 Master Gardeners about pests, natural enemies and
using biological control, in 8 all-day workshops in Illinois and Indiana.
Gardeners were surveyed about their pest management practices; then were
re-surveyed after one year, to see if they altered practices due to training
or serving as volunteer researchers. Gardeners conducted 4 research projects:
releasing Trichogramma against cabbage Lepidoptera; comparing
predators in pitfall traps in mulched and unmulched potato plots; testing
if spraying sugar water attracted or retained ladybird beetles; and using
entomophagous nematodes against iris borer.
Training about biological control affected gardeners’ use of pest
management alternatives. Before training, 63% of all gardeners used insecticides
more than once per year, vs. 28% after training. Only 14% of Indiana gardeners
never used insecticide before training, vs. 41% after training. Serving
as volunteer researchers caused an even greater impact. Volunteer researchers
who used biological control increased from 26% to 63%, and those who never
used insecticides increased from 27% to 43%.
In 1998, weekly releases of Trichogramma wasps resulted in fewer Lepidoptera larvae in cabbage. In control plots there were 0.59 larvae, vs. 0.11 larvae per plant with wasp releases. In 1999, numbers of cabbage Lepidoptera were very low. Control plots had 0.12 larvae per plant, versus 0.10 larvae per plant with releases; the two did not differ.
A total of 82 individuals of 9 species were found in 1998 in mulched plots,
versus 79 individuals of 10 species found in unmulched plots. Over twice
as many Cyclotrachelus sodalis were found in mulched plots than
in unmulched plots. In contrast, over twice as many Pterostichus permundus
and Scarites subterraneus were found in unmulched plots. In 1999,
639 individuals of 23 species were collected in mulched plots, versus
380 individuals of 31 species in unmulched plots. There were more than
2.7 times as many C. sodalis and C. convivus collected
in mulched plots than unmulched plots. In 1999, there were no differences
in numbers of H. pensylvanicus, P. permundus or S.
subterraneus between mulched and unmulched plots. Fourteen species
collected in unmulched plots in 1999 were not found in mulched plots,
whereas 6 species found in mulched plots were not found in unmulched plots.
Spraying
sugar water did not have a significant effect on retaining ladybird beetles
in tomato plots.
Iris plots
treated with nematodes in early-May averaged 24% of rhizomes with iris
borer damage, vs. 34% of rhizomes with damage in control plots, but the
difference was not significant. In the late-season treatments, only 11%
of rhizomes had evidence of boring by iris borer, vs. 24% damaged rhizomes
in control plots, but the difference was not significant.
Conclusions
Gardeners trained about biological control and that served as volunteer
researchers adopted practices to reduce their use of insecticides. Using
volunteer researchers is an excellent means to generate data from which
pest management recommendations can be made.
Impacts
Gardeners trained about biological control and pest management alternatives,
and who served as volunteer researchers, adopted practices to reduce insecticide
use. A reduction of more than 50% of gardeners using insecticides more
than once per year was due to training. Serving as volunteer researchers
caused an even greater impact; numbers who used biological control increased
from 26% to 63%.