Effects of storage temperature on viability and virulence of entomopathogenic nematodes Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae), Steinernema carpocapsae Weiser, 1955 and Steinernema feltiae Filipjev, 1934 (Rhabditida: Steinernematidae)

Abstract

Entomopathogenic nematodes (EPN) are a widely used biological control agent. The aim of the study was to detect efficacy and mortalities of some EPN stored at different temperatures and periods. Three EPN species were used in the study. They were Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae) HBH hybrid strain, Steinernema carpocapsae Weiser, 1955 TUR-S4 isolate and Steinernema feltiae Weiser, 1955 (Rhabditida: Steinernematidae) TUR-S3 isolate. The species were kept at 4, 15, 25 and 35°C for 7, 14 and 21 days. Subsequently, these species were applied at a dose of 15 Infective juveniles on Tenebrio molitor L., 1758 (Coleoptera: Tenebrionidae) larvae. The study was carried out in laboratory conditions in 2023. As a result, HBH and TUR-S4 kept at 25°C for 14 days and TUR-S3 for 21 days showed the highest virulence as 93.33%. Mortality rates of the EPN species kept at the specified temperatures were also determined. The results have showed that the highest mortality rates for the HBH, TUR-S4 and TUR-S3 isolates were 11.96% on the 14th day at 35°C, 19.81% on the 21st day at 25°C and 7.39% on the 21st day at 35°C, respectively. This study is an important step in determining suitable temperature conditions for storing and transporting EPN.