DIFFERENTIAL PARTICLE UPTAKE BY LARVAE OF 3 MOSQUITO SPECIES (DIPTERA, CULICIDAE)

Second and fourth instars of Culex quinquefasciatus Sav and Aedes aegy pti (L.) and fourth instars of Culiseta morsitans (Theobald) were fed five size classes of latex particles ranging from 0.56 to 5.75 mum. Ea ch experimental run was done on two size classes of particles mixed in different proportions of 10:90, 50:50, and 90: 10. Both the gut conte nts and the food mixtures were analyzed by flow cytometry, and the par ticle percentage composition was determined. The null hypothesis that no particle selection existed among instars or species was rejected fo r all species. Small instars ingested disproportionally more large par ticles in all suspensions. Cs. morsitans and Cx. quinquefasciatus show ed variability in their responses. Ae. aegypti almost always ingested more of the larger particles. Differences in particle size selection w ere related to head morphology and feeding mode. Under experimental co nditions, two parameters influenced particle size selection: the relat ive amount of small particles offered and the size difference between small and large particles. Flow cytometry analyses are recommended for quantitative studies of field material.