European journal of molecular biology and biochemistry

PREDATORY EFFICIENCY OF DIPLONYCHUS RUSTICUS (FABRICIUS, 1871) AGAINST CULEX LARVAE

Alwin Rajan D*

eugene_abner@yahoo.co.in

Prey, Predator, Belostomatid bug, Culex larvae, Attack rate and handling time Diplonychus rusticus.

Insects adapt themselves to aquatic habitats in spite of their terrestrial origin. Diplonychus rusticus inhabits both temporary and permanent freshwater bodies and they are found in abundant. Since it is an active predator on Culex larvae it is of great interest to verify the predator-prey relationship in relation to various factors such as prey density, prey size, period of exposure and the nutritional status of the predator controlling them. Hence the present study was conducted in laboratory condition to determine the predatory efficiency of well fed and starved Diplonychus rusticus using small and large sized Culex larvae in 1 litre and 5 litres water volume. The well-fed male and female bugs were subsequently exposed to different prey density (25, 50,100, 200 and 400) prey size (small and large Culex larvae) in 1 litre and 5 litres water volume. The number of prey killed after one hour and 24 hours duration was recorded for male and female water bugs separately. The number of prey killed by the predator were subjected to the procedure of random predator equation of Roger’s (1972) under non-linear square technique was used for statistical analysis. The predatory performances of both well fed and starved (male and female) bugs were highest after 24 hours not only at prey density 200in 1 litre water volume but, also at prey density 400 in 5 litres water volume. The predator preferred large sized Culex larvae than the small sized ones under well fed and starved condition. Based on the nutritional status, the predation rate was found to be high in starved condition than the well fed ones. With reference to the statistical constants of the predatory performance, attack rate (a) and handling time (Th), the present study revealed that the attack rate increased as the handling time of the bug decreased at various prey densities.