Oxydoras kneri as a Potential Candidate for the Biological Control of Mosquito-Vector Tropical Diseases

In this study, we assessed the larvivorous activity of Oxydoras kneri against Culicinae larvae in laboratory ex- periments to evaluate their suitability as a biological control. First, analysis of stomach content was performed to verify the feeding habits of the fish in their natural habitat. The behavior was then verified in aquarium experiments by feeding 2700 larvae to each fish. The feeding preference of the fish was evaluated in further experiments in which larvae and commercial fish food were offered, either separately or simultaneously. For both methods, the evaluation was performed by counting the number of adult mosquitoes that emerged during a 60-h observation period. The laboratory was main- tained at relatively stable temperature and humidity. The stomach content of 9 specimens of O. kneri captured in the Cuiaba River contained 26.5% insect larvae, with 11.5% exclusively from Diptera insects. The emergence of adults from insect larvae was not influenced by the presence of O. kneri. However, emergence was statistically lower in aquaria when the larvae were placed as food for the fish. The consumption of larvae and granulated commercial fish food was similar during a 60-h observation period, even when these items were offered separately or simultaneously. Since O. kneri are ubiquitous in the Amazon region, this finding highlights their potential role in the biological control of Culicidae mos- quito larvae growing in fish farm tanks. However, further studies are required to evaluate their behavior in the field and the operational difficulties of their use as a biological control.