Agriculture: Small Grains Pest Management Guidelines

Relative Toxicities of Insecticides and Miticides Used in Small Grains to Natural Enemies and Honey Bees

Common name
(Example trade name and formulation)
Mode of action 1 Selectivity2 (affected groups) Predatory mites 3 General predators 4 Parasites 4 Honey bees 5 Duration of impact to natural enemies 6
Bacillus thuringiensis ssp. kurstaki 11A narrow (caterpillars) L L L III none
dimethoate (EC) 1B broad (insects, mites) H H H I moderate to long
malathion (EC) 1B broad (insects, mites) H H H I short to moderate
H = high    M = moderate     L = low     — = no information
1 Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B; chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode-of-action group numbers are assigned by IRAC (Insecticide Resistance Action Committee).
2 Selectivity: Broad means it affects most groups of insects and mites; narrow means it affects only a few specific groups.
3 Generally, toxicities are to western predatory mite, Galendromus occidentalis.
4 Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific chemical depends on the species of predator or parasite, environmental conditions, and application rate.
5 Ratings are as follows: I–Do not apply or allow to drift to plants that are flowering; II–Do not apply or allow to drift to plants that are flowering, except when the application is made between sunset and midnight if allowed by the label and regulations; III–No bee precaution, except when required by the label or regulations. For more information about pesticide synergistic effects, see Bee precaution pesticide ratings.
6 Duration: Short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.

Acknowledgments: This table was compiled based on research data and experience of University of California scientists who work on a variety of crops and contribute to the Pest Management Guidelines database, and from Flint, M. L. and S. H. Dreistadt. 1998. Natural Enemies Handbook: An Illustrated Guide to Biological Pest Control, ANR Publication 3386.

Text Updated: 07/16