Oviposition dynamics of two released species of toxorhynchites (Diptera: Culidicae) and potential prey species

Releases of 122 T. brevipalpis, T. rutilus were made in a 4.6-ha oak-maple woodlot in northern Indiana to examine the spatial distribution of Toxorhynchites oviposition in relation to prey oviposition preferences. Oviposition was monitored at 25 sites with ovitraps suspended at 0.6, 3.0, and 6.1 m. Six weekly collections yielded 137,917 eggs of Aedes triseriatus and A. hendersoni and all 75 traps received eggs. Over a 28-day period, 1370 T. brevipalpis and 785 T. rutilus eggs were recovered. T. brevipalpis eggs were collected in 88% (66/75) of the trap and Tx. rutilus eggs were collected in 91% (68/75). Toxorhynchites eggs of 1 or both species were found in all traps. The T. brevipalpis mosquitoes deposited over 1/2 of their eggs in the 0.6-m traps, whereas the 3.0-m trap received the most T. rutilus eggs. Eggs of both Toxorhynchites species and the potential prey species were spatially aggregated within the woodlot. The spatial differences in oviposition between the 2 species of Toxorhynchites enhanced the degree of overlap in oviposition between the predators and the potential prey population.