Table 1.

Mechanisms of action, modes of application, and several limitations of some biological control agents.

Biological Control Agent	Commonly Used Strain	Effect	Application	Limitation	Corresponding Reference
Entomopathogenic fungi	Coelomomyces Culicinomyces Beauveria Metarhizium Lagenidium Entomophthora	Upon direct contact with the mosquito external cuticle. Slow killing. Affect the mosquito feeding habits. Affect the mosquito behavior and fitness conditions. Elevate the mosquito immune response and promote the production of secondary metabolites in the haemolymph.	In outdoor attracting odor traps. On indoor house surfaces. On cotton pieces hanging from the ceilings, bed nets and curtains.	Rapid fungal infection is required shortly after the mosquito picks up the malaria parasite.	[26,27,28,29,30,31,32,33]
Bacterial agents	Bacillus thuringiensis Bacillus sphaericus acetic acid bacteria (genus Asaia) wMelPop strain of Wolbachia	Suppress late instars and outgrowing pupae. Destroy larval stomach by endotoxin-proteins production. Rapidly colonize the male reproductive system and female eggs of many mosquito vectors.	At larval stages. At large scales. Through vertical transmission from mother to offspring.	Bti infections show no residual persistence post application. Only few studies address the effect of different bacterial agents on malaria vectors. Most of these studies are only experimentally approached without any further practical applications. Some bacterial strains like Wolbachia were not found to naturally infect Anopheles. Efforts to stably colonize wMelPop strains in A. gambiae failed.	[34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57]
Larvivorous fish	Gambusia affinis Cyprinodontidae Cyprinus carpio Ctenopharyngodon idella Tilapia spp.Catla catla Labeo rohita Cirrhinus mrigala Aphanius dispar Aplocheilus blocki Poecilia reticulata	Reduce larval density.	At larval stages. At low doses. In restricted open field system away from applied fertilizers and pesticides.	Great variability at the level of efficacy. Negatively affects the native fauna when introduced in many habitats. Require appropriate aquatic environments with reduced aquatic vegetations.	[55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71]
Microsporidian parasites	Vavraia culicis Edhazardia aedis	Combinatorial effects on different mosquito epidemiological traits: Decrease larval survival rates, decrease the number of adult mosquitoes, affect adult longevity, abort parasite development in the mosquito, affect mosquito biting rates.	At both larval and adult stages.	Seems only efficient when the effects on different mosquito epidemiological traits are combined.	[72,73,74,75,76,77,78,79,80]
Viruses	Densonucleosis viruses or denso viruses (DNVs)	Alter the ability of the mosquito to house the malaria parasite. Transduce certain anti-Plasmodium genes or specific Anopheles toxins in mosquito cells. Reduce mosquito longevity.	At both larval and adult stages. In the micro-environment of the host. Through vertical transmission among mosquito generations.	Only limited numbers of studies address the effect of viruses on malaria vectors control.	[81,82]
Nematodes	Different strains (like Romanomermis iyengari and Romanomermis culicivorax) of the Mermithidae species	Interfere in the mosquito reproductive behavior causing biological castration. Reduce mosquito populations. Decrease the rates of malaria transmission.	Mainly at larval stages.	Little is known about the parasitic effect of nematodes at the adult stages of mosquitoes.	[83,84,85,86,87,88]