Table 1.

Summary of characteristics of compounds used as larvicides

Larvicides	Mode of action	Advantages	Limitations	Residual effect
Bacterial larvicides	Induce the formation in larval midgut of a toxic pore that kill the mosquito by interrupting feeding and homeostasis	Harmless to most aquatic non-target organisms and humans, effective against insecticide resistant mosquitoes	Previous formulations had limited residual effect, require larvae to feed on, not active on late instar larvae and pupae	2 weeks previous formulations/up to 6 months for new formulations
Spinosyns	Toxic after ingestion and neurotoxic effect (bind to GABA and the nicotinic acetylcholine receptors and stop the normal transmission of nerve impulse and induce insect death).	Efficient against a large spectrum of species safe to non-target organisms, effective against insecticide resistant mosquitoes	Also used in agricultural, limited residual effect requiring frequent re-treatments	Short (1 to 3 weeks)
Petroleum products	Direct toxicity after ingestion or by contact reducing the mobility and prevent larvae from breathing causing suffocation and larval death	Control all mosquitoes, cheaper, easy to acquire, mosquito cannot develop resistance to the compound	Toxic to non-target species, frequent retreatment required, can be dispersed by wind, rain, vegetation or animals	Short (1 to 3 week)
Monomolecular surface films (MMF)	Prevent larvae from breathing and induce suffocation and larval death	Biodegradable, spread spontaneously over large water surface, safe to non-target organisms, mosquito cannot develop resistance to the compound	Can be dispersed by wind, rain, vegetation or animals	Short (up to 1 week)
Insect growth regulators	Prevent the development of larvae to adults or kill larvae when moulting	Efficient against several mosquito species, long residual effect, effective at low dosage, effective against insecticide resistant mosquitoes	Difficult to monitor if sites have been treated or not, toxic for non-target aquatic organisms	Long (3 to 6 months)
Essential oils and plant extracts	Toxic after ingestion or growth inhibiting effects	New compounds, could improve control of resistant mosquitoes	Not well characterised, no efficacy trial conducted, difficult to produce large quantities	Short
Synthetic chemicals	Neurotoxic compounds which kill insects by blocking the normal transmission of nerve impulses	Easy to implement, effective in polluted habitats	Can select for insecticide resistance, harmful to non-target organisms, frequent re-treatment required, only organophosphates approved for larval control	Long (several weeks)