INFORMATIONAL ITEM

Kirchneriella irregularis (Order Chlorococcales) Chlorella protothecoides (Order Chlorococcales)

Larvicidal Algae

· Although most algae are nutritious food for mosquito larvae, some species kill the larvae when ingested in large quantities.

· Blue-green algae that kill larvae do so by virtue of toxicity; however, the toxicity does not seem consistent for live algae to be useful for mosquito control.

· Culex and Anopheles larvae were virtually absent from a California rice field that had dense, filamentous, blue-green algae, although nearby fields without these algae had large populations of larvae.

· Certain species of green algae, Chlorococcales, kill larvae primarily because they are indigestible.

· Mosquito larvae are unable to complete their development if indigestible algae are numerous enough in the aquatic habitat to prevent the larvae ingesting enough other food to satisfy their nutritional needs. This sometimes happens in nature.

· Indigestible algae can achieve the necessary abundance to eliminate mosquito production when introduced to confined breeding habitats, such as ponds, dry wells, and detention basins. They continue to suppress mosquito production for years, even if the habitat dries out periodically.

· If, however, digestible algae are numerous at the time of indigestible algae introduction, the result can be a mixture that does not completely suppress mosquito production.

· A few possibilities would be to introduce an herbivore that feeds on digestible algae, or the chemical treatment of digestible algae of the habitat, before introducing indigestible algae.

· Further research and development will be necessary before their use is sufficiently reliable. The key improvement will be a method to ensure that larvicidal algae replace other algae in the aquatic habitat as completely as possible.