In the present study, infective capabilities of two entomopathogenic nematode species including Heterorhabditis bacteriophora and Steinernema carpocapsae were evaluated against red palm weevil, under laboratory and field conditions. Bioassay experiments took place to estimate theLC₅₀, LC₉₀, LT₅₀ and LT₉₀ values. By H. bacteriophora treatment, theLC₅₀'s against the 2^nd, 4^th, 8^th and 12^th larval instars of R. ferrugineus were 909.48, 1623.00, 1771.08 and 2897.44 IJs/ml, respectively. The correspondent LC₉₀ values were 3389.86, 6586.00, 8096.61 and 22548.21 IJs/ml, respectively after 15 days of treatment. Also, the LT₅₀ values after using the concentration 2500 IJs/ml were 7.43, 9.54, 10.83 and 16.28 days, respectively, while those of LT₉₀ were 21.81, 41.33, 52.68 and 116.40 days, respectively. By S. carpocapsae treatment, theLC₅₀'s were 728.97, 1370.00, 1547.21 and 2771.84 IJs/ml, respectively. LC₉₀ values were 3507.36, 6784.74, 9293.00 and 18916.27 IJs/ml, respectively for the 2^nd, 4^th, 8^th and 12^th instars after 15 days of treatment. Also, the LT₅₀ values after using the concentration 2500 IJs/ml were 7.04, 7.13, 10.16 and 14.62 days, respectively, while those of LT₉₀ were 19.05, 22.57, 43.46 and 96.78 days, respectively. Whereas, the two species of EPN (H. bacteriophora and S. carpocapsae) by 2500 IJs /ml concentration caused 90 & 95% mortality for 2^nd instar, 70 & 75% for 4^th instar, 65 & 70% for 8^th instar and 50 & 50% for 12^th instar, respectively, 15 days after treatment. The field study showed that infested date palm trees injected by H. bacteriophora and S. carpocapsae by concentration 2 x 10⁷ IJs/liter at the infestation site by the red palm weevil caused 60 and 80% recovery, respectively, recovery from infestation after 25 days of treatment.
The study recommends using of S. carpocapsae to control the red palm weevil.