Summary
The invasive red palm weevil (RPW) (Rhynchophorus ferrugineus) (Coleoptera: Curculionidae) is one of the most destructive palm pests in the world. More options are needed for its management, including optimised use of microbial entomopathogens (EP). The sub-lethal effects of an entomopathogenic fungus (EPF) Beauveria bassiana (isolate WG-11) (Ascomycota: Hypocreales) (at 1 × 104 spores ml−1) and two entomopathogenic nematode (EPN) species, Heterorhabditis bacteriophora (at 100 infective juveniles (IJ) ml−1) and Steinernema carpocapsae (at 50 IJ ml−1) were evaluated in various combinations against laboratory-reared 3rd, 5th and 8th instar larvae of RPW in bioassays. Individual and combined effects of both EP were observed after the pre-application of B. bassiana fungus at 0-, 1- and 2-week intervals. Combined treatments were tested for antagonistic, additive and synergistic effects. Additive and synergistic effects were observed in B. bassiana/S. carpocapsae and in B. bassiana/H. bacteriophora combined treatments. Early instar larvae of RPW were more susceptible than older instars. Sole and combined EP treatments decreased pupation, subsequent emergence of RPW adults and hatching. Sub-lethal effects of EP were observed in R. ferrugineus following application at the above-mentioned rates to 3rd, 5th and 8th instar larvae, including reduced larval weights, increased larval, pre-pupal and pupal durations, reduced adult weights and life spans. Simultaneous combined applications of B. bassiana/S. carpocapsae and B. bassiana/H. bacteriophora at the above-mentioned rates against last instar (9th) larvae of R. ferrugineus reduced food consumption, frass production and affected weight gains.
Compartive Efficiency of Egyptian Entomopathogenic Nematodes and Imidacloprid on the Red Palm Weevil, Rhynchophorus ferrugineus Oliv