Mechanical Distribution ofChrysoperla rufilabrisandTrichogramma pretiosum:Survival and Uniformity of Discharge after Spray Dispersal in an Aqueous Suspension

The feasibility of spraying an aqueous suspension containing biological control organisms was investigated as an improved means for their distribution.Chrysoperla rufilabris(Burmeister) eggs andTrichogramma pretiosum(Riley) from parasitized eggs ofEphestia kuhniella(Zeller) were submerged in water to determine their survival after exposure to wetting. The hatching rate forC. rufilabrisand the emergence rate ofT. pretiosumadults were not significantly affected by submergence in water and agitation for up to 3 h. Additional experiments determined the uniformity of distribution, measured as the concentration of eggs per unit of liquid volume, and survival of eggs from spraying through a large-orifice fan nozzle. The hatching rate forC. rufilabrisand the emergence rate forT. pretiosumwere not affected by spraying of the suspension. The test suspensions ofC. rufilabrisandT. pretiosumwere agitated using an air sparge and a mechanical paddle, respectively, during 1-h spray experiments. The concentration of eggs in the suspension discharged from the spray nozzle was relatively constant during the experiment, although eggs of both species showed trends toward a decreasing concentration.