Effects of Size and Concentration of Particles on Rates of Ingestion of Latex Particulates by Mosquito Larvae1

Abstract

Using suspensions of uniform latex microspheres, differences in rates of ingestion due to particle concentration and size were examined in filter-feeding larvae of Culex pipiens L. (Diptera: Culicidae). With suspensions having particle diameters that allowed optimal ingestion, rates of ingestion by 4th instars were optimal for particulate concentrations (weight/volume) ranging from 0.03 to 4%; ingestion rates fell off sharply at concentrations below 0.03%. For all instars, ingestion rates declined markedly with decreasing mean particle diameters below 0.71 µ. Optimal ingestion occurred with suspensions of mean particle diameters ranging from 0.71 up to 1.86 μ for the 1st instar, 7.6 μ for the 2nd and 3rd instars, and 26 µ for the 4th instar, above which sizes ingestion rates declined with increasing size. Almost no particulate of the 91-µ mean diameter size was ingested by 2nd instars, and absolutely none of both 45 and 91-µ mean diameter sizes by 1st instars.