Evaluating the use of native ornamental plant cultivars for insect herbivores
Date
2017
Authors
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Publisher
University of Delaware
Abstract
Native plants are becoming more commonly used in ornamental gardening as a
way to help combat the many environmental issues caused by urbanization. Designing
anthropogenic habitats that promote insect diversity and abundance may be paramount
for reconciliation efforts. Plant breeders have introduced many cultivars of native
plants to improve the aesthetic value, disease resistance, or site adaption of the plant
that may positively or negatively impact wildlife. There has been a debate as to
whether or not native cultivars have the same ecological value as their wild type
counterparts. This remains to be tested. ☐ In this study I focus on the use of native plant cultivars for wildlife value,
specifically for insect herbivore-driven food webs. These cultivars often have
chemical or physical properties that have been altered from the straight species which
may alter an insect’s ability to locate and consume its host plant. I chose six cultivar
traits that are commonly sought after in woody plant cultivar selections to compare
insect feeding, abundance and species richness between the cultivars and the wild type
plants. An experimental garden plot was established with cultivars and their parent
species at the Mt. Cuba Center in Hockessin, Delaware. Three experiments explored
the differences between the cultivars and their straight species. First, the garden was
used to sample the insect community and abundance associated with each species and
cultivar. Second, I conducted a feeding trial with the bagworm Thyridopteryx
ephemeraeformis in which neonate caterpillars were offered a choice of the cultivars
and parent plants and amount of feeding on each was compared. Lastly, I conducted
an end-of-season leaf damage analyses to compare the average amount of feeding
damage that had accumulated on leaves in the garden plots by September. ☐ Results showed a deterrence of feeding on cultivars that had leaves altered
from green to red color. Results for the other traits varied from test to test and by plant
species, but many often showed no difference from the straight species. In a few cases
insects showed a preference for the cultivar over the straight species. Thus, the
usefulness of native cultivars in restoring insect driven food webs may, in many
situations, depend on the suitability of the cultivar trait and/or the plant species from
which the selection was derived.
Description
Keywords
Biological sciences