Potential of entomopathogenic nematodes against the pupal stage of the apple maggot (Walsh) (Diptera: Tephritidae).

The apple maggot, (Walsh) (Diptera: Tephritidae), is considered a key pest of apples and is native to the eastern United States. The virulence of seven different species of entomopathogenic nematodes (EPN) was assessed against pupae of under laboratory conditions. Nematode species and strains included (ALL strain), (SN strain), (355 strain), (VS strain), (VS strain), (HOM1 strain), and (UK211 strain). We conducted three bioassays: (i) short-term exposure cup bioassay (7 d), (ii) long-term cup bioassay (30 d), and (iii) pot bioassay (30 d). In the short-term exposure bioassay, all nematode strains (applied at 54 infective juvenile nematodes (IJs) cm) significantly reduced (range: 42.9-73.8%) insect survival relative to the control, but no differences were observed among the treatments. For the long-term exposure bioassay, using the same EPN application rate as the short exposure assay, all treatments reduced adult emergence compared with the control. was the most virulent (28.3% survival), and and were the least virulent (53.3% survival). In the pot experiment, and (applied at 27 IJs cm) had the highest virulence (23.3 and 31.7% survival of , respectively), while was the least effective (68.33% survival). Our results indicate that , , and have substantial potential to attack pupae, and their field application under the tree canopy (prior to adult emergence) in the spring when temperatures are conducive might be a good option for successful IPM of apple maggot fly. The apple maggot, (Walsh) (Diptera: Tephritidae), is considered a key pest of apples and is native to the eastern United States. The virulence of seven different species of entomopathogenic nematodes (EPN) was assessed against pupae of under laboratory conditions. Nematode species and strains included (ALL strain), (SN strain), (355 strain), (VS strain), (VS strain), (HOM1 strain), and (UK211 strain). We conducted three bioassays: (i) short-term exposure cup bioassay (7 d), (ii) long-term cup bioassay (30 d), and (iii) pot bioassay (30 d). In the short-term exposure bioassay, all nematode strains (applied at 54 infective juvenile nematodes (IJs) cm) significantly reduced (range: 42.9-73.8%) insect survival relative to the control, but no differences were observed among the treatments. For the long-term exposure bioassay, using the same EPN application rate as the short exposure assay, all treatments reduced adult emergence compared with the control. was the most virulent (28.3% survival), and and were the least virulent (53.3% survival). In the pot experiment, and (applied at 27 IJs cm) had the highest virulence (23.3 and 31.7% survival of , respectively), while was the least effective (68.33% survival). Our results indicate that , , and have substantial potential to attack pupae, and their field application under the tree canopy (prior to adult emergence) in the spring when temperatures are conducive might be a good option for successful IPM of apple maggot fly.