Distribution of entomopathogenic nematodes in a biopesticide spray

Application technology for biological insecticides like entomopathogenic nematodes (EPN) has been relatively neglected. One of the major considerations related to the selection and use of an application system is the application distribution pattern. A completely uniform distribution of the nematodes in soil applications is not essential because the nematodes can move over short distances; however, a uniform distribution is important in foliar EPN applications. The present study examined the volumetric distribution pattern of Steinernema feltiae beneath single standard flat-fan, air-induction, deflector, and Twin Jet spray nozzles. A comparison with the distribution of a chemical tracer was made to reveal possible distribution problems. Droplet size spectra of the nozzles were measured and linked with the distribution results. A theoretical calculation of the coefficient of variation of the nematode distribution beneath a spray boom was performed. Finally, the actual spray pattern of the EPN on a horizontal surface beneath a spray boom was studied. We can conclude that the volumetric distribution pattern of EPN is influenced by nozzle type and is different from the volumetric distribution pattern of a chemical compound beneath a TT 110 08 deflector nozzle. The spray overlap from a spray boom decreases differences in nematode distribution to an acceptable level. Nozzle type significantly influences the number of nematodes deposited on a horizontal Petri dish and their distribution within the droplets. Future experiments are needed to reveal if the measured differences in deposition and coverage due to nozzle type will result in significant differences in pest control.