Grantee Research Project Results

Reducing Pesticide Use in Cotton by Managing the Western Tarnished Plant Bug (Lygus hesperus) from a Landscape Perspective

EPA Grant Number: F07F20987
Title: Reducing Pesticide Use in Cotton by Managing the Western Tarnished Plant Bug (Lygus hesperus) from a Landscape Perspective
Investigators: Sheller, Frances J.
Institution: University of California - Davis
EPA Project Officer: Lee, Sonja
Project Period: September 27, 2007 through September 27, 2010
RFA: STAR Graduate Fellowships (2007) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , Academic Fellowships , Fellowship - Insect Ecology , Fellowship - Landscape Ecology , Fellowship - Agricultural Ecology

Objective:

The Western Tarnished Plant Bug (Lygus hesperus) is a major pest of cotton and many other agricultural crops, including beans, lettuce, seed alfalfa, strawberries, and tree fruits. As a highly mobile generalist herbivore Lygus disperses frequently across the agricultural landscape, often rapidly increasing population densities in economically susceptible crops to the extent that insecticides are required to protect the yield. These rapid shifts in pest densities demonstrate that Lygus densities within a field are not solely a result of the grower’s in-field management practices but instead depend upon migration events initiated outside the field. Effective Lygus management must, therefore, be done at the landscape level.

To manage Lygus from a landscape perspective, it is essential to understand its dispersal capability. Specifically, quantifying long-distance dispersal is essential for understanding the colonization potential of highly mobile insects. The smallest-scale local movements undertaken by the majority of the focal population do not sufficiently explain the speed and spread of the seasonal redistribution of insect populations. It is also important to determine the relative contribution of long distance versus local dispersal, and of different source types, in the colonization of economically vulnerable cotton fields. A better understanding of this relationship will lead to optimal landscape configurations that minimize the probability of damaging densities of Lygus occurring in cotton.

Approach:

To understand Lygus hesperus dispersal capability, a modified mark recapture experiment will be conducted in which a field containing a large population of Lygus will be marked with inexpensive and readily available proteins. Following harvest of the field, these marked individuals will be captured in surrounding cotton fields at specific distances away from the point of emigration, and tested for the protein mark using an enzyme-linked immunosorbent assay (ELISA). The results of the ELISA will be used to create a density-distance curve of marked individuals and quantify the tail of this distribution. This information will then be used in the determination of the ‘zone of influence’ of each Lygus source on economically vulnerable crops.

Expected Results:

The findings of this project will quantify Lygus hesperus dispersal ability and measure the relative contribution of local versus long-distance sources to Lygus populations in economically susceptible crops like cotton. Additionally, these results will illustrate the need to manage Lygus from the landscape perspective. Knowledge gained can be used to create agricultural landscapes that minimize the density of Lygus in cotton, which will reduce the necessity for pesticide applications.

Supplemental Keywords:

Lygus hesperus, long distance dispersal, local dispersal, aseasonal migration, cotton, landscape scale management, source zone of influence, enzyme-linked immunosorbent assay (ELISA), mark recapture,

Progress and Final Reports:

2008

2009

Final