Larvicides

All mosquitoes must have water in which to complete their life cycle, however not all mosquitoes prefer the same conditions. Some mosquito larvae develop in polluted or brackish water environments and some prefer freshwater. Similarly, some mosquito species prefer to lay their eggs on small water bodies (eg. puddles, hoof prints or in small containers) whilst others prefer the shallow margins of larger water bodies. The type and number of breeding sites within any given area is a good indication of the types of vectors which may be present (and how abundant they are).

This diversity of breeding preferences can be well illustrated by considering two important vector genera such as Anopheles (a genus which contains the malaria vectors) and Aedes (containing the major vectors of dengue and yellow fever):
  • Most species of Anopheles prefer clean, unpolluted water and larvae have been found in fresh or salt-water marshes, mangrove swamps, rice fields, grassy ditches, the edges of streams and rivers, and small, temporary rain pools. Many species prefer habitats with vegetation whilst others prefer habitats that have none. Some breed in open, sun-lit pools while others prefer shaded breeding sites in forests, tree holes or the leaf axils of some plants.
  • The major vector species within the genus Aedes (Aedes aegypti and Aedes albopictus) are recognised as container-breeding species, preferring small volumes of water (artificial or natural) and encompassing environments like rainwater in used tires, discarded tins and plastic containers, abandoned car parts, water-collecting trays under plant-pots and natural situations such as the water collected in dead leaves, tree holes, and rock pools.

Targeting the breeding sites of mosquitoes is generally an attractive option for control since a relatively large number of larvae will be present within a much smaller area compared to the much larger treatment area required for the (far-more-dispersed) flying adults.

Breeding sites can be targeted either through engineering initiatives (eg: drainage schemes), improved sanitation (eg: removal of debris which can catch rain water) or through specific targeting with mosquito larvicides. Often, if the former approaches are done well then there is little need for the latter. However, in many situations, the nature of the environment provides little choice but to integrate methods in order to achieve satisfactory results. The diversity in breeding site preferences between species can present a challenge for effective implementation, especially where mixed species are present.

In the past, oil has been commonly used as an effective, but environmentally unsound, larval control agent; spreading across the surface of water bodies and suffocating the larvae. However a number of more targeted compounds are now available. Each of these are designed to target mosquito larvae at very low dose rates with minimal impact on non-target organisms. There are biological larvicides available as well as synthetic options.

Environmental Science recognizes the importance of larviciding as part of mosquito control and, in addition to our in-house chemistry ( triflumuron) which is used in some parts of the world; we have formed alliances with other suppliers to combine our broader technical expertise and presence in certain regions, with specific product solutions which are well designed for the local environments. Our in-house option is illustrated below. For specific information on regional products please contact the relevant local offices.
Product Active ingredient Formulation type Insecticide family
StarycideTriflumuronSuspension concentrateInsect growth regulator (chitin synthesis inhibitor)

* Starycide does not have WHOPES Recommendation

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