The compatibility of single and combined applications of the entomopathogenic nematode, Heterorhabditis indica with imidacloprid against red palm weevil, Rhynchophorus ferrugineus (Oliv.)

The present study aimed to investigate the biological potential of the entomopathogenic nematode (Heterorhabditis indica) for the management of the red palm weevil, Rhynchophorus ferrugineus O. and to evaluate its possible synergies with an insecticide application. Entomopathogenic nematode (EPN) and imidacloprid were applied either individually or in combinations. The virulence of EPN and imidacloprid was tested for three larval stages and the adults of R. ferrugineus. Moreover, pupation rate, adult emergence and egg eclosion were determined at sub-lethal doses. Our results showed that the mortality rate in all three larval stages and adults of R. ferrugineus was highest in combined treatments in comparison to single treatments. However, when compared to fourth and sixth instar larvae, second instar larvae were most susceptible, while the mortality rate was increasing over time. The mean mortality rate in adults was lower than in the larval stages. Furthermore, egg eclosion, pupation and adult emergence were lowest in the combined applications of EPN and imidacloprid. This research could contribute to the effective management of R. ferrugineus, especially in areas where it has developed pesticide resistance.