Determination of the efficacy of some entomopathogenic nematodes against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) under laboratory conditions

Abstract

The tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) which was first detected in Izmir Province, Turkey in 2009 has spread quickly and has become the major pest in tomato producing areas. The efficacy of three different entomopathogenic nematode (EPN) species isolates (from e-nema ® GmbH Schwentinental, Germany), Heterorhabditis bacteriophora (Poinar), Steinernema carpocapsae (Weiser) and Steinernema feltiae (Filipjev) was investigated against T. absoluta during 2013-2014 under laboratory conditions. The EPNs were applied with different inoculation rates (1, 2, 5, 10, 15, 20, 25 and 40 infective juveniles per larva) for each species to the third instar larvae of T. absoluta outside the leaves. The mortality rates for H. bacteriophora, S. carpocapsae and S. feltiae were found between 21.2 - 74.2%, 28.8 - 99.4% and 17.5 - 95.2%, respectively. According to the results, S. carpocapsae and S. feltiae caused similar mortalities at the given inoculation rates while H. bacteriophora had lower efficacy compared to those two species. The values of LD 50 for H. bacteriophora, S. carpocapsae and S. feltiae were 21.67, 7.13 and 6.25 infective juveniles per larva, respectively. Based on these data, S. feltiae was the most efficient nematode species, and was then applied against the larva of T. absoluta inside the mines and pupae. However, S. feltiae only caused low mortality of larvae both inside mines (19%) and the pupae (7%). These results revealed that EPN have good potential for the control of T. absoluta larvae outside the leaves and should be studied further.