Prevention of disease transmission by mosquitoes and other insects requires a multifaceted approach, which includes killing mosquitoes with pesticides and larvicides. Biological control has received less interest over the last 3 decades, but now regaining interest because of the resistance of mosquitoes to the chemical approach.
Biological control may also be achieved by the use of predators that prey on mosquito larvae in stagnant pools. The use of larvivorous fishes (fishes that feed on larvae, such as Gambusia affinis), has been employed successfully for many decades. However, Gambusia is an aggressive fish that has displaced many indigenous fishes, thus causing environmental concern in areas where they are introduced. Using larvivorous fishes is an approach employed only in countries where Gambusia has already been introduced or is naturally present. Another drawback of using conventional fishes is that mosquitoes primarily breed in stagnant bodies of water which dry up seasonally. The introduction of Gambusia is effective only during the wet season and will require restocking after the dry season passes and the next rainy season sets in.
Besides their unique life cycle, there are advantages to the use of annual killifishes:
• Their small size (approximately five to seven cm.) enables them to seek predators in shallow corners of the pool and under/in between the leaves of water plants.
• Their small size also makes them less suitable as a food source by local human population that co-inhabit these areas.
• They are rarely aggressive and have never been found to develop populations in permanent bodies of freshwater.
• The sturdy eggs can be mass-produced, thus making it possible to carry millions of embryos for dissemination in difficult terrain usually found in malarious areas.
Tests on predatory activity of annual fishes.
The data in Table 1 show that different species have different rate of consumption, with the South American species of C. whiteii showing the highest consumption. There were no sex differences in total food consumption, except in C. whiteii where the females showed 4 times higher food consumption despite being half the size of the males.. These fishes can live almost exclusively on mosquito larvae when no other food is present. However, ponds are inhabited by many species of insect larvae and other life forms that serve as food during the rainy season. The data demonstrate that these fishes are predatory to mosquito larvae and may serve as a biological control in isolated pools of fresh water.
The results for N. guentheri showed that the larger the fishes, the greater the larval consumption rate.
Research on understanding the mechanisms that control the onset of duration of arrested development (also known as suspended animation or diapause) has been undertaken by Poseidon scientists for several decades. The level of knowledge about the biology of these fishes has reached the stage where it is now possible to mass produce annual species for biocontrol trials. For more information about annual fish biology please CLICK HERE.
Poseidon’s goal is to embark on mass production of annual killifishes to support future use of these fishes for biological control of mosquitoes and insects. The control of suspended animation also has major implications in studies on health, disease, and aging. Mass production will also enable the company to support the expansion of research in this area for possible applications in biomedical sciences.