Evaluation of Virulence of Steinernema carpocapsae and a Local strain Steinernema sp. against Melolontha melolontha Larvae

This study evaluates virulence of Steinernema carpocapsae and a locally isolated Steinernema strain against Melolontha melolontha larvae, as a significant agricultural pest. Comparative bioassays were conducted to determine mortality rates, lethal concentration (LC50), and lethal time (LT50) under controlled conditions. Results indicate that both nematode strains effectively infect and kill the larvae, with significant differences in efficacy depending on nematode concentration and larval instar stage. The findings support the potential use of local Steinernema strains for sustainable pest management. In laboratory conditions, the effectiveness of pathogenic nematodes from the genus Steinernema was evaluated for controlling harmful insects. The experiment included the commercial strain Steinernema carpocapsae and a local species, Steinernema spp.. The study was conducted at temperatures of 25°C and 30°C, using two concentrations of nematode suspensions: 2500 and 3000 infective juveniles (IJs) per 1 ml of water. The findings revealed that the effective concentration against the May beetle (Melolontha melolontha) should be at least 2500 nematodes per 1 ml of water, with an optimal temperature of 25°C. Based on insect mortality rates and temperature indices, it was confirmed that both Steinernema carpocapsae (commercial strain) and the local Steinernema spp. exhibit high pathogenicity. Therefore, their application against the pest Melolontha melolontha is well-justified.