<p>The
primary goal of this research study was to provide updated pest management
recommendations to growers, including the reduction of insecticide applications
on a calendar basis by the use of pest economic thresholds, with the purpose of
maximizing insecticide efficacy while minimizing the associated negative
impacts on natural enemies and their ecosystem services. </p>
<p>Commercial
watermelon (<i>Citrullus lanatus</i>) production in the Midwest
typically relies on neonicotinoid and pyrethroid insecticides to manage insect
pests, particularly striped and spotted cucumber beetles (<i>Acalymma vittatum </i>Fabricius and <i>Diabrotica undecimpunctata</i> <i>howardi</i>
Barber, respectively). The role of arthropod predators in managing cucumber
beetles is not well documented, and data
on the effects of insecticides on predators in watermelon production are deficient.
Common cucumber beetle predators include coccinellid beetles found on plants,
ground-dwelling carabid beetles (Coleoptera: Carabidae) and spiders in several
families that inhabit the soil surface in watermelon fields. I hypothesize that these generalist predators
and the ecosystem services (e.g., pest predation) they provide are at risk from
insecticides used for pest management without regard to economic thresholds. My
study compared the effect of insecticide use on cucumber beetle pests, spider
predators, collembola populations and field pest predation under two
treatments: 1) watermelons treated with
neonicotinoid soil drench and subsequent pyrethroid sprays, surrounded by corn
with neonicotinoid-treated seeds (Conventional),
and 2) watermelons treated only with pyrethroid spray when economic thresholds
were reached, surrounded by corn with untreated seeds (IPM).</p>
<p>The frequent application of
insecticides decreased cucumber beetles in the
watermelon plots managed with Conventional pest management; however, they also reduced spider predators,
collembola densities, and field pests predation measurements, possibly due to
the subsequent pyrethroids applications during the growing season. In addition, our study showed that
neonicotinoid seed treatment in corn had no negative impact on any of the above-mentioned
response variables measured. </p>
<p>Ultimately, following an IPM strategy and the
use of pest monitoring helped to reduce unnecessary insecticides applications, conservation
of pest regulatory services provided by natural enemies, and possibly less ecological
impact to manage significant insect pests in watermelon plots. <b><br>
</b></p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/11303405 |
| Date | 02 December 2019 |
| Creators | Ivan Grijalva (8066012) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/Impact_of_Insecticides_on_Cucumber_Beetles_Coleoptera_Chrysomelidae_and_Spider_Predators_in_Watermelon_and_Corn/11303405 |
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