Biological Control of Mosquito Larvae using Gambozia Fish — Bosaso Puntland Somalia
Introduction
The conceptual development of biological control of mosquito fish was firstly proposed by Harry S. Smith in 1919. Biological control is the deliberate use of natural enemies to reduce the number of pest organisms. Therefore, biological control of vectors is an essential and effective means for controlling transmission of several mosquito-borne diseases such as malaria, filariasis, dengue fever; etc. Biological control is advantageous because it is generally host-specific with limited non-target effects. Thus, biological larval control tools appear to be given more emphasis than chemical tools (World Health Organization, 2009).
The use of larvivarous fishes was presently most popular biological method for reducing mosquito larvae population.
Currently, there is no amending information concerning mosquito biological control of fish.
Somalia. Study of mosquito biological control in Somalia ecosystem is not yet well recognized, in addition there is no remarkable information of mosquito biological control of fish recorded and documented in Somalia ecosystem since 1981 (WHO, 1981).
Therefore, the present paper is designed to update the information regarding biological control of mosquitoes fish in Puntland , in order to promote and renew this study in Puntland and expect to become good preliminary relevant information and data that can be useful obtainable for future expectance and become reference.
Gambusia affinis
Gambusia is a large genus of fish in family Poeciliidae (order Cyprinodontiformes). Gambusia contains over 40 species, most of which are principally found in freshwater habitats, though some species may also be found in brackish or saltwater habitats. Gambusia species are often called topminnows or simply gambusias; they are also known as mosquito fish, which, however, refers more specifically to two species, G. affinis and G. holbrooki.
The mosquito fish, Gambusia, is a top-feeding minnow and is a known good larvivorous fish with wide distribution in countries in the Eastern Mediterranean Region. It is unique in its global distribution and is small, tiny, grey or greyish black, measuring up to 4–6 cm in length. Gambusia has been used in many parts of the world to control mosquito larvae. The fish occupies some curious habitats, such as tunnels, abandoned pools, ponds, rainwater pools, stagnant rice fields, etc. This fish is suitable for low temperature areas, as it is known to survive subzero temperatures.This fish has proved useful in primary or sole-source mosquito breeding sites. It is reputed to have shown potential to reduce mosquito populations throughout the world.
Advantage of biological control of larvivorous fish
Among the biological control agents of mosquitoes, fishes are the most extensively used species in several countries since the beginning of the twentieth century. This century, mosquito biological was considered to root control vector of mosquitoes for many diseases that have been reported 25000 deaths annually (Gubler et al., 1998). However, in the past five decades, the incidence was reported to have decreased 30-folds (Kindhauser, 2003), since the world implemented to used larvivorous fish as biological vector of a disease control.
Besides, using of Larvivorous fish was important to mosquitoes control programmes in the 20th century (For the Isis album), particularly in urban and periurban areas for immediate use in developed and developing countries (Davidson 1981, Jahn 1996). Moreover, this aspect has become a very positive role to play in the integrated control methodologies of mosquito vector diseases. Biological control of mosquito larvae with predators and other biocontrol agents would be a more effective and ecological friendly approach, avoiding the use of synthetic chemicals that concomitant damage to the environment (Thomas & Pasteur, Nicole. 1999).
Understanding of larvivorous fish control in the world.
The side effects of insecticide and larvicide are the root problems practice of today which are used for control the vector of animal and human diseases of mosquitoes are increased in the world .
Therefore, nowadays larvivoro fish of Oreochromis spilurus spirulus, Nothobranchius, Anphanius dispar and Gambusia affinis are a great way to reduce mosquito populations before it become problems such transferring diseases. Modern researchers are inclined to use biocontrol agents rather than chemical insecticides due to the residual effects of chemical insecticides, widespread resistance in target insects, and high refusal rate for indoor spray, soaring price of chemical insecticides and other operational difficulties. Among the numerous mosquito predators of fish have been used since the early 1900s for mosquito control and are the most commonly used biological control agent for the vectors of malaria in many countries in the worldwide. Use of larvivorous fishes in the field of mosquito control is well documented since the 20th century.
Significant of Larvivorous fish for biological control of mosquito
The worldwide mosquito problems are still a major of animal and human health related issue. Efforts in mosquito control have involved chemical pesticides, but this method has become harmful to the environment and has increased the likelihood of pest resistance in the target insects. An interest in using larvivorous fishes for the control of mosquitoes has existed for several decades since larvivorous freshwater fishes have been shown to be effective natural enemies of mosquito larvae control.
The reliable with present-day knowledge, such fishes possess a number of attributes that would make them good candidates for biological control because of their innate predatory characteristics. They are capable of significantly reducing natural populations of mosquito larvae and have a broad host range as well as a great potential for the long-term control of mosquitoes in the field since they survive and reproduce naturally in the fresh water streams.
Therefore, larvivorous fish are the fish that feed on mosquito larvae. They have been widely used around the world in attempts to control mosquito-borne diseases and mosquito nuisance. Among all the bio-control agents and larvivorous, fish are widely used in vector control of mosquito.
Comparison between of larvivarous fish and other methods of mosquito control
While there are reports of resistance of mosquito control to chemicals, nowadays their application is still a major tool that health agencies have against the mosquito vector, whose populations are invading new habitats due to the global warming. However, the persistent use of chemicals conveys a high risk for a serious and real trouble of resistance .
Despite the immense number of technical reports and scientific papers published yearly about bio-control of mosquito fish. Therefore, most of the natural enemies of biological are larvivorous fish, which are best currently, and Future Tactics of sub-urban and urban transmission diseases.
Larval control investigation and strategy analysis in Somali ecosystem
Larvivarous fish is the principal vector of mosquito control in Somalia ecosystem. It breeds in man-made cemented reservoirs (birkets), shallow standing or moving waters with algae in streams or riverbeds, rainwater pools, ponds with grassy margins, moderately polluted household wastewaters, sunlit wells and irrigation channels.
In Somalia ecosystem, there are three main larval habitats (yadav 2001) villages with large cement lined man-made reservoirs (birkets); earthen ponds (wars or bulleys); villages along streams often with shallow sunlit wells used for irrigation and occasionally with wars and urban areas with waters storage practices including rainwater harvesting tanks, wars, wells, and some pools. Larvicides have been used in Somalia since 1945 and several projects using larvivorous fishes have been implemented in Somalia since 1980.There is limited evidence of the success of larval control in Somalia and public health officials seem skeptical about its implementation, as it requires high levels of community participation/acceptance and substantial technical, logistical and financial efforts. In addition, according to current WHO recommendations, “larval control is indicated only for vectors breeding in permanent or semi -permanent water bodies that can be identified and treated with relatively short cycles and where the density of the human population to be protected is sufficiently high to justify the treatment of all the breeding places.
Bosaso Intervention-Larvivorous fish for mosquito control as a Pilot Project
Bosaso is one of the most growing cities in Puntland and is critically challenged with a vast distribution of water storage tanks (berkads). Hence, implementing of environmental management and engineering techniques in terms of covering berkads, filling in low-lying areas, protecting disused Wells, proper cleaning of public latrines from stagnant waters, constructing proper shared berkads for poor communities, controlling water used in building construction in densely populated old residential areas of Biyokulule present many obstacles and difficulties for malaria control program. Comprehensive public health legislation with law enforcement is a Must when dealing with such chronic obstacles. In the meantime, biological larvicides is recommended which is the safest method in mosquito control. It uses larvivorous fish such as the top water minnow or mosquito fish (Gambusia affinis) or the common guppy (Poecilia reticulate) for the control of mosquito population.
Collection of larvivarous fish from the stream of Iskushuban by using locally made fishnets. The density of the fish in the stream was very high and transported the fish in Jergans one- third filled with water . The net is held by rope from both the sides of the pond and others keep the net intact in the middle and move across the hatchery, thus pulling the net with entrapped fish to a shallow corner (see Annex).
During the short survey, the numbers of people that have met was 900 villages Bosaso and selected for interviews individually were old people who have empirical knowledge of larvivorous fish experience; they composed both (young) and adult. Those elders have been asked about the larvivorous fish control, past uses, places obtaining larvivorous fish for mosquito control, existence place where fish found in Puntland and its distributions of the country. Therefore, they suggested same idea according to role of mosquito fish uses and they comprised elders,
Conclusion
This short survey become a baseline study of larvivorous fish will be supportive to the malaria and mosquito borne diseases control activities in Puntland at Bosaso District. Therefore, the use of chemicals in mosquito control appears to have many disadvantages. It is harmful to non-target populations as well as the environment pollution and causes resistant to mosquitoes.
Larvivorous fish has many advantages as compared to chemicals because it can be effective method and safe to human, animal and non-target populations. in addition, it has low cost effective and lower risk of resistance development.
Despite that community acceptance and participation was much better than study expected. It seems that almost all the owners were ready to accept the introduction of larvivorous fish into their barkits (water reservoir) and to participate in the completely sustainable activity in the future.
Although a cost effective comparison of the use of fish and other control method has not a problem to use, the investigation clearly demonstrates that the method is very economical in addition to being devoid of all the hazard and complication attendant on residual application s for control mosquito.
However, the advantage of the study has been sufficiently to enlist the cooperation of the community. Therefore, in future other study must be preceded thorough this study.
The study has confirmed that the one species of larvivarous fish are available Iskushuban streams in Puntland Somalia.
Recommendation
Having ascertained the presence of larvivorous fish and its availabilities and breeding sites mosquitoes in the study area, and poor level of mosquito biological control. Therefore, the following points are recommended.
· Biological control of larvivorous fish should be given attention and implemented since it very beneficial.
· Government should conduct awareness and training for the communities to use larvivorous fish as a biological of mosquito fish.
· Government should plan and initiated the further research for identifying the breeding sites of larvirous streams found all Puntliland regions.
· Most of the Somali dwellers in cities and some of the rural areas uses water tank/reservoirs, which is a good breeding site for mosquitoes. In fact, mosquitoes biting are a constant problem almost of the whole year. Therefore, Government should implement appropriate water supply in cities to eliminate mosquitos’ problem.
· Relevant authorities of mosquito fish should be generating in various regions in Puntliland. Since is known to be the most effective mode of mosquito control comparing to chemical.
· To document mosquito biological control in the whole country for future use is urgently require.
· To collect data for similar research study at large scope in Puntliland should be standard and need.
· The time of short –term for one year to study for distribution and classification of more indigenous larvivorous fish in streams in Puntliland is not sufficient. Therefore, it is necessary to discuss this aspect and to conduct further analysis.
· The present of larvivorous fish and level knowledge of community will not make possible to conduct the uses of larvivorous fish as biological control. Therefore, government should instruct orientation, knowledge and provide technical support for the community to use biological control.
· Government should hold and launch nationwide campaign to the entire country without too much of strain on the cost, since it is fit and approached environmental health.
