Predatory Capacity of Mesocyclops aspericornis on Late Instar Aedes aegypti L. Larvae at Varying Prey Densities

Abstract

Previous researches on the predatory capacity of Mesocyclops aspericornis, being a promising approach to the biological control of mosquitoes, have been conducted using first instar larvae. The present study investigated copepod predation on late instars based on the counts of dead larvae per unit volument of the water column. Larvae of the Aedes aegypti instar numbering from 10 to 100 were pipetted into 10 enamel containers containing 100 ml dechlorinated tap water. Larval density was increased at increment of 10 for each container. A single M. aspericornis was added to each container and counts of surviving larvae were recorded after 24 hours. Statistical analysis revealed that with increasing prey density, the predatory capacity of M. aspericornis also increased. Its predator satiation was reached at a prey density of 70/cl. for the second and third instars and at a prey density of 60/cL for fourth instars. Also, mortalities decreased with advancing larval development and peaked at mean values of 16.20, 14.20, and 9.0 foir the second, third, and fourth instars, respectively. The coefficient of determination (R2) values of 0.0206, 0.0438, and 0.1189 for the second, third and fourth instars, respectively, from the linear regression between mean mortality (expressed as log mean counts/cL) and prey density suggest a prey-predator interaction similar to a type II functional response. The data show differential influences of development- and density-associated characteristics of mosquito larvae on the prediation of M. aspericornis.