Potential of entomopathogenic nematodes (Rhabditida: Heterorhabditidae) to control Mediterranean fruit fly (Diptera: Tephritidae) soil stages

Entomopathogenic nematodes are presented as an additional tool for Ceratitis capitata control, focusing on the soil stages. This study showed the importance of testing native tropical strains adapted to tropical weather conditions. We tested eight strains, six of them native to Brazil, in sand columns against 3 instar larvae (L3) of C. capitata. The highest mean mortality values were reached by Heterorhabditis sp. LPP17, Heterorhabditis sp. LPP14 and H. baujardi LPP7 with 98.5, 95.5 and 90% mortality, respectively. These three tropical strains were also tested against C. capitata L3 at six different concentrations, and results show that mortality increases with IJ concentration. H. baujardi LPP7, at 45 IJs/3 larvae or 237 IJs/cm, caused 81.5% mortality, and 100% at 105 IJs/3 larvae or 552.6 IJs/cm. On the other hand, pupal mortality above 80% was only observed at 155 IJs/3 pupae or 816 IJs/cm or 197 IJs/cm; a concentration three times higher than to kill larvae. When four different temperatures were tested against L3 and one-day-old pupae, H. baujardi LPP7 performed better at 24 and 28C. In a guava orchard, H. baujardi LPP7 was tested against C. capitata L3, and the average larval mortality in treated trees was significantly different in relation to the control (58.6% and 7.7%, respectively). When the experiment was repeated, the same positive tendency was reached (87.4% and 30.4%, respectively). We conclude that H. baujardi LPP7, as a native tropical strain, is well adapted to field conditions tested and may be one more tool for controlling C. capitata soil stages, as part of an integrated pest management of pests in guava. This study showed the importance of testing native tropical strains adapted to tropical weather conditions.