The use of annual killifish in the biocontrol of the aquatic stages of mosquitoes in temporary bodies of fresh water; a potential new tool in vector control

Abstract

BackgroundMosquitoes that breed in temporary pools in remote areas that dry up seasonally are especially difficult to control through chemical or biological means. The annual killifish has been suggested as a means of eradicating the aquatic stages of mosquitoes in transient pools because they can maintain permanent populations in such habitats by undergoing suspended animation or diapause during the embryonic stages to survive periodic drought. However, very little is known about the predatory activity of annual killifish and their usefulness in mosquito control.ResultsThe annual killifish, Nothobranchius guentheri, native to Tanzania, was used in this investigation. Food preference was tested under laboratory conditions by feeding juvenile killifish with 2nd instar mosquito larvae of Culex quinquefasciatus in the presence of alternative food sources, such as rotifers and chironomid larvae. Semi-field tests were conducted by introduction of hibernating killifish embryos and juvenile fish to artificial ponds in an outdoor open environment that allowed natural oviposition of Cx. quinquefasciatus. Food preference studies show that N. guentheri preferred to prey on mosquito larvae than either chironomid or rotifers. When hibernating killifish embryos were added to ponds simultaneously with the addition of freshwater, the embryos hatched and fed on mosquito larval population resulting in complete elimination of the immature stages. The introduction of juvenile fish to ponds with high density of mosquito larvae resulted in total eradication of the mosquito population due to predation by fish. Complete biocontrol of the mosquito larval population was achieved in the presence of 3 fish per m2 of pond surface area.ConclusionsThe annual killifish provides yet another tool that may be employed in the eradication diseases carried by mosquitoes through vector control, particularly in temporary bodies of freshwater. The fish can be conveniently transported in the absence of water in the form of hibernating embryos. Once introduced either as embryos or juveniles in ponds, the annual killifish can effectively reduce the larval population because of its aggressive predatory activity.

Some ambient environmental conditions, food and reproductive habits of the banded lampeye killifish Aplocheilichthys spilauchen in the Kakum estuary wetland, Ghana

“…When seasonal pools dry, the diapausing embryos survive in the dry substrate, and hatch at the start of the rains to re-populate the pools. As indicated by Matias and Adrias (2010), this life cycle which coincides with that of their potential prey such as mosquitoes that also begin their life cycle in the same seasonal pools provides a compelling reason for the interest in the potential of killifish for vector control in seasonal habitats.…”

“…Regardless of this growing interest, few studies have looked at the prospects of some killifish for this purpose in Africa (Ghosh et al 2004;Howard et al 2007), with the well explored ones being species of the genus Nothobranchius common in Tanzania (Matias and Adrias 2010). However, there are other species that have a wider geographical distribution on the continent that may also be suitable candidates in the localities where they occur, but have remained unexplored.…”

“…Consequently, the focus of recent efforts point to developing indigenous and less aggressive aquarium fishes as alternative in providing mosquito larval control in streams and pools (Ghosh et al 2004; ephemeral aquatic environments such as seasonal pools. Their suitability lies in the fact that most species feed on insect larvae and small invertebrates from water surface (Holden and Reed 1991;Dankwa et al 1999), and are non-aggressive when mixed with other species (Matias and Adrias 2010). Most importantly, they have the ability to survive prolonged drought by producing diapausal embryos which are highly resistant to environmental extremes such as drought, high temperature, anoxia and physical as well as chemical damage (Matias 1982;Holden and Reed 1991;Podrabsky et al 2001).…”

“…However, the increasing development of chemically resistant substrains of mosquitoes, coupled with the ecosystem damage caused by chemicals used in the vector control process, has renewed interest in biological control alternatives to complement other mosquitoes control programs (Dabire et al 2008;Munhenga et al 2008). According to Hamouda and Samraoui (2007) as well as Matias and Adrias (2010), the mosquito fish (Gambusia affinis) was eventually selected for worldwide mosquito control because of its high larvivorous capacity, high fecundity and adaptability to new environments, but was not successful due to its intrinsic aggressive nature which nearly resulted in the extinction of many other native species. Consequently, the focus of recent efforts point to developing indigenous and less aggressive aquarium fishes as alternative in providing mosquito larval control in streams and pools (Ghosh et al 2004; ephemeral aquatic environments such as seasonal pools.…”

Diurnal variation in the feeding patterns and food preferences of Dwarf panchax (Aplocheilus parvus)

“…Ghosh et al (2011) indicated that the important of using surface feeding predators like Poecilia reticulata and Gambusia affinis in chikungunya vector control programs. Further the patentability of annual killifish, Nothobranchius guentheri on mosquito control in temporary water bodies was proposed by Matias and Adrias (2010) due to surface living and insectivore nature of these fishes.…”