Efficacy of a native isolate of Steinernema feltiae on tomato leafminer (Tuta absoluta) under laboratory and greenhouse conditions

The tomato leafminer, Tuta absoluta (Meyrick) (Lep., Gelechiidae) is a devastating key pest of tomato, and its damage may reach up to 100%. Here, the potential of the infective juveniles (IJs) of the entomopathogenic nematode Steinernema feltiae Filipjev species on different larval stadia of T. absoluta was studied under laboratory conditions and the ability of most effective nematode concentration when applied in the greenhouse conditions. In the in vitro, the six concentrations of third-infective juveniles S. feltiae (0, 125, 200, 355, 632 and 1124 IJs/ml) were tested against the three larval instars, L2, L3 and L4 of T. absoluta. Forty eight hours after infection, the entomopathogenic nematode was able to infect all instars of the pest. With increasing density of S. feltiae, the pest larva mortality also increased with a significant difference at 1% probability level. The percentage mortality of L2, L3 and L4 at the highest concentration of nematodes (1124 IJs) were 31.5, 75.6 and 85.9%, respectively. These values at the lowest concentration of nematodes (125 IJs) were 16.8, 26.7, and 30.3%. In the greenhouse test, three treatments included; S. feltiae (1124 IJs/ml), Bacillus thuringiensis (0.25%, Belthirul 32% WP, Probelte Co.) and control in a completely randomized design with six replicates were conducted. The percentage mortality of different T. absoluta larval stages by S. feltiae and B. thuringiensis treatments were 77.5%±2.9 and 40%±13.7 with a significant difference at 1% probability level. The results indicate the potential of S. feltiae as a native entomopathogenic nematode could be used in an integrated management measure in controlling of the T. absoluta.