Under laboratory conditions, the activity of two entomopathogenic nematodes, Heterorhabditis bacteriophora (HP88) and Steinernema carpocapsae (AT4), as well as their compatibility with two common insecticide formulations (Lambada cyhalothrin and Flubendiamide) and one insect growth regulator (Lufenuron), were evaluated against Spodoptera frugiperda. The nematodes IJs were subjected to the LC50 and LC25 of insecticides, and the viability of infective juveniles (IJs) was measured before being tested against Galleria mellonella larvae to determine IJs pathogenicity. Also, the mixtures were evaluated against the 4th larvae of S. frugiperda to select one mixture can serve in integrated pest management (IPM) in agro-ecosystems.
Results showed that H. bacteriophora strain (HP88) was more efficient with higher pathogenicity and virulence against S. frugiperda (LC50= 48.67±0.34IJs/ml-1) than S. carpocapsae (AT4) (LC50= 65.88± 3.04). Flubendiamidee was the most toxic insecticide (LC50 = 3.26±0.52) followed by Lambada cyhalothrin (4.23±0.8PPM). Lufenuron was the least toxic one (5.67±1.53PPM). Both EPN H. bacteriophora (HP88) and S. carpocapsae viability was not affected by any of tested insecticides (LC25 and LC50), while Lambada cyhalothrin reduced S. carpocapsae pathogenicity with LC50 concentration. Lufenuron at the rate LC50 and Lc25, not affect H. bacteriophora and S. carpocapsae pathogenicity. All tested insecticides with the two doses were harmless according to IOBC test. All mixtures of insecticides with the two EPN strains were synergistic effect against 4 th larvae of S frugiperda except Lufeuron with Lc25 was antagonist. It was explored how these nematode insecticide combinations could be used in maize pest management