Effects of thiamethoxam seed treatments on nutritive sources available to Orius insidiosus say in Indiana soybean agroecosystems
Abstract
Land planted in soybeans in the United States totaled over 77 million acres in 2012, with an estimated 60% receiving a preplanting seed treatment of a neonicotinoid, typically thiamethoxam. Neonicotinoids are known to have severe toxic effects on pollinating insects, however the extent of damage caused to populations of other beneficial insects, such as omnivores in the field, is largely unknown. These experiments aimed to categorize the effects of thiamethoxam seed treatments on a resident omnivore, Orius insidiosus in terms of possible prey reduction as well as exposure via phytophagy and pollenivory. This was accomplished via field experiments, feeding assays, and quantitative methodologies to determine levels of thiamethoxam in plant tissue and pollen. Results revealed consistent differences in O. insidiosus populations occurring later in the season, which are expected to be large independent from thrips populations. Further analyses revealed that high levels of thiamethoxam is found in treated plant tissue early in the season, however it dissipates quickly, in line with literature values. No detectable levels of any neonicotinoid (or metabolite) were found in any pollen samples.
Degree
M.S.
Advisors
Krupke, Purdue University.
Subject Area
Ecology|Entomology
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.