Assessing the Influence of Plant Growth Regulator Herbicide Vapor Drift on Arthropod Communities in Field Crop Agro-Ecosystems

EPA Grant Number: FP917431
Title: Assessing the Influence of Plant Growth Regulator Herbicide Vapor Drift on Arthropod Communities in Field Crop Agro-Ecosystems
Investigators: Bohnenblust, Eric Walter
Institution: Pennsylvania State University
EPA Project Officer: Lee, Sonja
Project Period: August 1, 2012 through July 31, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Entomology


Herbicide resistant weeds are a major problem facing the future of modern agriculture. This research will look at the effects of applying the plant growth regulator herbicide, dicamba, directly to several different insects. Also, plants will be sprayed with various herbicide doses and insects will be allowed to feed on them to understand how insect behavior, insect growth, plant chemistry and plant nutrition change when plants are sublethally dosed with herbicides.


The study will use a series of laboratory, greenhouse and field studies to look at the effects of sub-lethal doses of the plant growth regulator herbicide, dicamba, on insects directly and indirectly. Studies focusing on indirect effects will be performed in the greenhouse and field where insects will feed on plants that have been dosed with different rates of dicamba. The study will look at insect growth with caterpillars, population growth with aphids and behavior of pollinating insects. Studies focusing on direct effects will be performed in the laboratory and the greenhouse where insects will be topically dosed with one of six dosage rates, and toxicity will be assessed based on mortality. The study also will look at chemical compounds that plants use for defense against insects to see if a plant’s ability to defend itself against insect herbivores changes after herbicide damage has occurred.

Expected Results:

Sub-lethal herbicide damage is likely to have negative consequences for plant health. This in turn could lead to positive or negative effects on insects. Plants that are not healthy may not provide the best floral resources for pollinators, potentially further stressing honeybees. Unhealthy plants also may have a lower nutritional quality, stunting the growth of caterpillars. Additionally, plant defenses are likely to be impaired, potentially exacerbating pest problems as aphid populations may be higher on herbicide stressed plants, and the impaired defenses also may reduce the ability of the plant to recruit natural enemies that control pests.

Potential to Further Environmental/Human Health Protection

This research will provide a risk assessment for plant growth regulator herbicides that likely are to be applied increasingly more often in the near future. It will inform regulators, farmers and industry about some of the potential risks associated with use of these plant growth regulator herbicides and influence future plant growth regulator use patterns.

Supplemental Keywords:

plant growth regulator herbicide, transgenic crops, pollinators

Progress and Final Reports:

  • 2013
  • 2014
  • Final