Larvicide

Larvicide is a type of pesticide designed to kill the larval stage of insects. It is used in agriculture, public health, and vector control to reduce populations of pests such as mosquitoes, black flies, and midges by targeting larvae in aquatic or semi-aquatic habitats. By focusing on larvae, larvicides can reduce adult insect populations with potentially lower exposure to humans and non-target organisms when applied appropriately.

Larvicides may be chemical, biological, or environmental/physical. Chemical larvicides include organophosphates such as temephos and, in some programs, fenthion or malathion, as well as juvenile hormone analogs like methoprene and pyriproxyfen and growth inhibitors such as diflubenzuron. Biological larvicides rely on living organisms or their products, notably bacteria such as Bacillus thuringiensis israelensis (Bti) and Bacillus sphaericus, whose toxins disrupt larval digestion or development. Environmental or physical methods include habitat modification and the use of physical barriers or biological control agents to reduce habitat suitability.

Application typically involves applying the larvicide to water bodies where larvae develop, such as ponds, irrigation channels, tires, catch basins, or floodwater areas. Some products are formulated for point-of-use application, while others are long-lasting or require periodic reapplication. Efficacy depends on habitat characteristics, larval density, and timing to intercept peak breeding.

Larviciding aims to minimize risks to humans and non-target species; Bti and Bs are generally selective for certain dipteran larvae, whereas broad-spectrum chemical larvicides can affect non-target aquatic organisms and accumulate with repeated use. Integrated pest management strategies emphasize monitoring, resistance management, and combining larviciding with habitat management and chemical controls as needed. Regulatory approval and guidance vary by country and use-case.