Efficacy of indigenous larvivorous fishes against Culex quinquefasciatus in the presence of alternative prey: Implications for biological control

Abstract

Background & objectives: Indigenous larvivorous fishes bear potential for regulating vector mosquitoes throughtrophic interactions. The mosquito prey preference of five indigenous larvivorous fishes in the presence of alternativefood items was assessed to highlight their use in mosquito vector management.Methods: Laboratory experiments were carried out using the larvivorous fishes Ambassis (=Chanda) nama,Parambassis (=Chanda) ranga, Colisa fasciatus, Esomus danricus and Aplocheilus panchax, as predators and IVinstar Culex quinquefasciatus larvae as target prey. Mosquito prey preference of these fishes in the presence ofchironomid larvae, tubificid worms and artificial fish foods, in varied proportions, were assessed using preferenceindex.Results: The fishes consumed considerable amount of mosquito larvae both in absence and presence of alternativefood items. However, the positive selectivity for mosquito larvae at all densities were significantly (p <0.05)affected by the alternative foods. The chironomid larvae and tubificid worms were consumed proportionatelyhigher than expected (p <0.05), while the artificial fish food was consumed at lower than expected proportions(p <0.05). The niche overlap was significantly similar among the fish species suggesting likeliness in predationpattern and prey preference.Interpretation & conclusion: The results reflect that the alternative food items influence the mosquito prey selectivityand thus the efficacy of indigenous larvivorous fishes. While use of these fishes in the wetlands and allied mosquitolarval habitats in different parts of the country is suggested, impact of the alternative prey may affect the successfulregulation of mosquitoes. Assessment of appropriate predator-prey ratio under natural habitat conditions isrecommended to enhance successful mosquito control by these fishes.

Keywords

• Biological control
• chironomid larvae
• indigenous larvivorous fish
• mosquito larvae
• prey preference
• tubificid worms