What is the role of grassland vegetation in grasshopper population dynamics?

O.Olfert

Objectives:
Examine "the role of host-plants in managing grasshopper populations".

Status Report:
Complete

Summary:
The 50 million ha of the western Canadian prairie region is now divided between 30 million ha of small-grain crops and 20 million ha of native grassland or seeded perennial grasses and forage. This has changed the habitat for grasshoppers. Changes in farming practices also impact grasshopper populations.

Host-plant resistance may be an effective means of reducing grasshopper outbreaks. It includes characteristics that make the plant less attractive, less nutritive, more toxic, or that allow the plant to tolerate insect damage. Cereal cultivars have been developed with resistance to other insect pests. Characteristics such as surface layers of wax, secondary chemicals such as alkaloids, tannins and protease inhibitors or toughness can discourage feeding, or reduce grasshopper performance. In the field, the cultivars that are least damaged by grasshoppers are generally those that have the most negative effects on grasshopper potential.

Host-plant resistance can be used by selecting resistant species such as perennial grasses for roadsides and margins, by selecting resistant crop cultivars such as pea and oat, by using barrier and trap strips to alter grasshopper movements, and by examining farming practices and altering those that contribute to grasshopper outbreaks.

Impact:
Currently, costs of grasshopper damage for organic producers and of grasshopper controls for conventional, are in the millions of dollars. "Effective suppression of grasshopper populations would reduce the overall need for insecticides, an approach which is supportive of the concept of managing grasshopper outbreaks without risking environmental disaster."

Research Establishment:
Saskatoon Research Station, Agriculture and Agri-Food Canada

Funding Sources:
Agriculture and Agri-Food Canada

Researchers and Contact Information:
O.Olfert, Saskatoon Research Station, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, Saskatchewan S7N 0X2, Canada.

Citation: Chapter 3 in J.A. Lockwood et al (eds.) Grasshoppers and Grassland Health, 61-70. 2000 Kluwer Academic Publishers. Netherlands