Dr. Bugs: Anthranilic diamide insecticides By Raymond A. Cloyd

Question: Can you please provide information on the insecticides associated with the Insecticide Resistance Action Committee (IRAC) group 28?

Raymond Cloyd, professor, Kansas State University

Answer: Insecticides in the IRAC group 28 are referred to as anthranilic diamides. There are three IRAC group 28 insecticides labeled for use in greenhouse production systems: Acelepryn, Mainspring and Sarisa. Acelepyrn (with active ingredient of chlorantraniliprole) is labeled for use against caterpillars (foliar application) and aphids (growing medium application). Mainspring (with active ingredient of cyantraniliprole) is labeled for use against aphids, thrips and whiteflies (foliar and growing medium applications). Sarisa (with active ingredient of cyclaniliprole) is labeled for use against caterpillars, beetles, leafminers, mealybugs, thrips and whiteflies (foliar application). There is another insecticide product, Pradia, which is a mixture of cyclaniliprole (the active ingredient in Sarisa) and flonicamid (the active ingredient in Aria).

Anthranilic diamide insecticides are mobile in the xylem (water-conducting tissues) but have a low water solubility ranging from 0.10 to 14.2 ppm (mg/L). Anthranilic diamide insecticides have contact, translaminar or systemic activity against targeted insect pests. Studies have indicated that anthranilic diamide insecticides may have repellent or antifeedant properties.

The mode of action of anthranilic diamide insecticides is associated with modulation or varying the properties of the ryanodine receptors (ryanodine receptor modulators). Normally, ryanodine receptor channels regulate the movement of calcium within muscle cells of the insect, which is important for muscle contraction and relaxation. Anthranilic diamide insecticides bind to the ryanodine receptors, which keeps the channels open, resulting in an uncontrolled release of stored muscle calcium from cells. Consequently, normal muscle contraction is disrupted leading to paralysis and eventually death of insect pests.

Table 1. Common name (active ingredient), trade name, restricted entry interval (REI), targeted insect pests (based on label information) and water solubility of Insecticide Resistance Action Committee (IRAC) group 28 insecticides.

Studies have shown anthranilic diamide insecticides are not harmful to bees and certain biological control agents. In our research at Kansas State University in Manhattan, Kansas, however, we found that cyantraniliprole (Mainspring) was directly harmful to adults of the rove beetle, Dalotia coriaria, and insidious flower bug, Orius insidiosus. Table 1 presents information associated with the IRAC group 28 insecticides.

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Raymond A. Cloyd is professor and extension specialist in horticultural entomology/plant protection at Kansas State University. He can be reached at rcloyd@ksu.edu.