Effect of mini-sprinkler irrigation system on Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juvenile

Abstract

Entomopathogenic nematodes (EPNs) are currently being used as successful biological control agents of soil-dwelling insect pests. Previous field and greenhouse studies demonstrated that application techniques and non-biotic factors (temperature and pressure) have a significant effect on EPNs efficacy. The objective of this study was to evaluate the influence of an irrigation spray application system on the viability, infectivity and host search capability of Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juveniles (IJ). Two assays were proposed. Their viability was evaluated under the microscope after the IJ passed through the irrigation system. Infectivity on Galleria mellonella larvae, and host search capability, as evidenced by larval mortality, were evaluated in containers (Experiment 1). In the field (Experiment 2), mortality of G. mellonella larvae was evaluated under different nematode concentrations (0, 100,000, 300,000 and 500,000 IJ per tree). No differences were recorded on the viability, infectivity and host search capability of the IJ in Experiment 1. In Experiment 2, differences were recorded among the different concentrations used (p < 0.05), and a higher mortality was observed at the highest nematode concentration (28.3% and 37% in each one of the two experiment repetitions). This irrigation system did not affected adversely the viability, infectivity and host search capability of H. baujardi LPP7.

Entomopathogenic Nematode Application Technology

“…In another example, Beck et al, (2013) noted that an ISO 02 flat fan nozzle can clog when spraying S. carpocapsae, and that an ISO 04 standard flat fan nozzle is a better nozzle than the larger ISO 08 standard flat fan nozzle for spraying S. carpocapsae because the former provided a higher relative deposition on cauliflower leaves. H. baujardi LPP7, when applied though an irrigation system composed of mini-sprinklers with one-mm fan nozzles (20-35 psi), was not affected in viability, infectivity and host searching capability (Lara, Dolinski, Sousa, & Daher, 2008).…”

Spray Nozzles, Pressures, Additives and Stirring Time on Viability and Pathogenicity of Entomopathogenic Nematodes (Nematoda: Rhabditida) for Greenhouses

“…Fife et al [10] considered thermal influences during pump recirculation to be more detrimental to EPN than mechanical stress Therefore, pumps with lower capacity, such as diaphragm or roller pumps, seem to be better for biopesticides. According to Lara et al [11], in one hour of agitation, the tank mixture temperature can increase from 22 to 43°C in a tank with a centrifugal pump, and from 22 to 27°C in a tank with diaphragm or peristaltic pumps. Therefore, temperature and stirring of the tank mixture are also important factors to consider in the application of EPN.…”

Studies on entomopathogenic nematodes in Brazil: past and future

“…An experiment conducted with IJs of H. baujardi LPP7 revealed that this nematode can tolerate temperatures up to 35 °C for 2 hours and pressures as high as 340 psi for 30 minutes [88] . It was also demonstrated that the viability, infectivity and searching ability of H. baujardi LPP7 were not affected after passing through a microspray irrigation system, indicating the potential of this type of application on crops [89] . In a study with S. glaseri to evaluate the effect of pressurization of the spray suspension on the viability of IJs, it was found that pressure up to 1,379 MPa did not affect this nematode [90] .…”