Evaluation of entomopathogenic nematodes against red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

The entomopathogenic nematodes play a pivotal role as bio-control agents of different species of insect pests including red palm weevil. In current investigations, infective capabilities of four species of entomopathogenic nematodes including Hetrerorhabditis bacteriophora, Steinernema feltiae, Steinernema glesri and Steinernema carpocapsae were evaluated against larvae, pupae and adult red palm weevil, under laboratory and field conditions. The pathogenic potential of selected nematode species was assessed based on dissection and adult emergence of weevils. Results indicated that S. carpocapsae and H. bacteriophora with 94.68 and 92.68% infection were found most effective EPN species against red palm weevil larvae. Focusing the adult emergence, aforementioned EPNs were found most pathogenic when pupae of red palm weevil were treated and resulted into 83.60 and 80.20% infested pupae. It was noted that the adult emergence is the better option for the evaluation of pathogenic potential of EPN compared to dissection of insect. The S. carpocapsae was found most effective against 6th instar larvae of red palm weevil and caused 100% mortality at 340 hours after treatment; whereas; S. glesri and S. feltiae were found least pathogenic and caused 70 and 76% mortality. All the evaluated nematode species were found highly infective under field conditions. The S. carpocapsae was found most pathogenic causing 83.60% mortality of red palm weevil. Overall; the tested nematodes were found most effective against larvae followed by adult weevils. The tested nematode species were found least effective against pupae of red palm weevil. Based on current findings, it is concluded that the tested species of nematodes can be used as sustainable option for the management of red palm weevil.