Efficacy and residual activity of commercially available entomopathogenic nematode strains for Mediterranean fruit fly control and their ability to infect infested fruits

BACKGROUND Entomopathogenic nematodes (EPN) show potential in controlling larvae of the Mediterranean fruit fly (medfly) Ceratitis capitate, but previous studies mainly concern species and strains that are not commercially available. The use of EPN for control of Mediterranean fruit fly is further hampered by the cost of using nematodes. In this study, the efficacy and residual activity of commercial strains of three EPN species, Steinernema carp omicron capsae, S. feltiae and Heter omicron rhabditis bacteri omicron ph omicron ra medfly) C. capitata, in the soil substrate and inside fruits were evaluated. RESULTS Suspensions of these species were applied at a dose of 1.5 mi m(-2) on a soil substrate wherein medfly larvae were added sequentially for a period of 4 weeks post application at 20 degrees C. S. feltiae provided the highest suppression up to 50% as assessed by adult medfly emergence because it had the highest immediate activity and long residual activity. Furthermore, S. feltiae, and to a lesser degree S. carpocapsae, were able to move and infect medfly larvae inside infested apples and oranges left in the surface of the substrate wherein EPN were applied, reducing significantly adult medfly emergence (60-78%). CONCLUSION These results support the efficacy and feasibility of applying a single, relatively low dose of S. feltiae in autumn, off-season, targeting overwintering medfly larvae with the scope of reducing the number of adult medflies emerging later in the new season.

Automated summary

The study found that among the three commercial EPN species, S. feltiae had the highest suppression effect and longest duration. Additionally, S. feltiae and S. carpocapsae were able to infect medfly larvae inside fruits, significantly reducing the emergence of adult medflies.