Original Article Effect of Salting on Houseflies (Musca domestica) and Beetles (Necrobia rufipes and Dermestes maculatus) Infestation of Fish from Lake Victoria, Kenya

The effect of salting on houseflies (Musca domestica) and beetles (Necrobia rufipes and Dermestes maculatus) infestation of fish from Lake Victoria, Kenya, was studied. Sun-dried fish (Rastrineobola argentea and Oreochromis niloticus) samples for isolation of beetles, and fresh fish samples and houseflies for the salting experiments were collected from fish landing and processing beaches in the shores of Lake Victoria, Kenya. Results showed that all the salt concentrations ranges tested (5%-30%) repelled house flies though at different degrees. 5% repelled 68.8%, 10% repelled 72.4% and 30% repelled 82.8%. The mean number of flies which had settled on the control (no salt) chamber was significantly higher (12.20) than the mean number of flies which had settled on the experimental (salted fish tissues) chamber (3.45), p=0.00009, Students t-Test. Results from beetles’ infestation experiments showed that at salt concentrations 10-30%, all the Necrobia spp adult beetles were dead compared to Dermestes spp of which some adults were still alive at 25% salt concentration. Percentage weight loss due to beetle’s infestation of unsalted (control) dried dagaa or tilapia fish tissues were over 50%. Even 5-10% salt concentration reduced weight loss due to beetles’ infestation of the dried fish to between 1.6% and 10%, compared to infestation of the unsalted fish. After 48 days of Dermestes and Necrobia spp beetles infestation, the mean weight of unsalted dagaa and tilapia fish tissues combined was significantly reduced to 2.05g compared to the mean weight of 4.68g of 5% salted dagaa and tilapia fish tissues combined, p=0.0002, Students t-test. These results are important because the repellency effect of salting of fish on houseflies and infestation reduction on beetles can help reduce microbial contamination and post-harvest losses of fish. © 2013 Universal Research Publications. All rights reserved