Chlorantraniliprole is a modern, broad-spectrum insecticide used in agriculture to manage insect populations across various crops. It belongs to the anthranilic diamides, a new chemical class valued for its unique mode of action and favorable environmental profile. As a selective pest control agent, it helps protect crops from a wide range of insects, particularly those resistant to older chemicals. Commercially known by trade names such as Coragen and Rynaxypyr, it has been designated a reduced-risk pesticide by the United States Environmental Protection Agency.
How the Insecticide Works
The mechanism of action for chlorantraniliprole targets the insect muscular system rather than the nervous system, distinguishing it from many older insecticides. It functions as a modulator of insect ryanodine receptors (RyRs), which are specialized calcium channels located within muscle cells. The ryanodine receptor regulates the release of calcium ions ($\text{Ca}^{2+}$) from internal storage sites, a process fundamental to muscle contraction.
When an insect ingests or absorbs chlorantraniliprole, the compound binds to the RyR, causing the channel to open and remain unregulated. This activation results in a large efflux of calcium ions from the cell’s internal stores, rapidly depleting the calcium supply needed for normal muscle function. The physiological effect is immediate muscle paralysis, leading to the rapid cessation of feeding and disorientation. This quick stop to feeding is a significant advantage in crop protection, as it limits the damage inflicted by the pest shortly after exposure.
What Pests It Controls
Chlorantraniliprole is effective against many insect pests, showing particular strength against the larval stages of moths and butterflies (Lepidoptera). Target pests include caterpillars such as armyworms, cutworms, the diamondback moth, and various bollworms and borers.
Beyond Lepidoptera, the insecticide controls certain species in other insect orders, demonstrating effectiveness against some beetles (Coleoptera), such as the Colorado potato beetle and the Japanese beetle. It also controls some species of flies (Diptera) and is used for specific rice pests like the rice leaf roller and stem borer. The compound is applied in various formulations, including as a foliar spray, a soil treatment for systemic uptake, or as a seed treatment to protect seedlings.
Environmental and Non-Target Safety
The favorable toxicological and ecotoxicological profile of chlorantraniliprole is a primary reason for its widespread adoption in integrated pest management programs. Studies indicate the compound is practically non-toxic to mammals, birds, and fish. This low toxicity occurs because ryanodine receptors in vertebrates are significantly less sensitive to the insecticide, often 400 to 3000 times less responsive than those in susceptible insects.
In mammals, the compound has demonstrated low acute oral, dermal, and inhalation toxicity, and is not neurotoxic, immunotoxic, or carcinogenic. For birds, acute studies show minimal effects even at high doses. Similarly, fish are considered low risk under acute exposure scenarios, though some aquatic invertebrates are more sensitive.
The impact on beneficial insects, including pollinators, is important. Chlorantraniliprole exhibits low acute toxicity to adult honeybees when used according to label instructions. This selectivity extends to many beneficial predatory insects and parasitic wasps. However, research suggests a higher sensitivity for honeybee larvae, where exposure to low doses can result in mortality before adulthood. Therefore, careful adherence to application guidelines is necessary to protect vulnerable non-target organisms.