Effectiveness of varying application rates of entomopathogenic nematode, Steinernema riobrave, in controlling plum curculio (Conotrachelus nenuphar) in peaches

The entomopathogenic nematode Steinernema riobrave has been found in field trials to be highly effective at controlling the larval stage of the Plum Curculio (Conotrachelus nenuphar), a major pest of fruit crops throughout much of North America. While these trials have shown the efficacy of S. riobrave as a control agent, the majority have been carried out using a very high concentration of infective juveniles (IJ); around 100 individuals per cm² of soil, an application rate which would not be economically viable in most commercial farms due to the cost of S. riobrave preparations. We investigated whether effective control could be achieved using a lower application rate of S. riobrave, comparing 100, 50 and 25 IJ cm^-2 with an untreated control by assessing the survival of C. nenuphar larvae introduced into emergence traps established in peach orchards in New Jersey and Georgia. In all cases mortality was very high but initial data showed that it was significantly lower in untreated controls (91.3%), while there was no significant difference between the three S. riobrave treatments ( > 99% in all three cases). This has positive implications for the use of S. riobrave in the control of C. nenuphar as it suggests effective results can be achieved with a four-fold decrease in application rate, with concomitant reduction in material costs