Evaluation of the entomopathogenic fungus beauveria bassiana and its prospects in controlling the red plam weevil rhynchophorus ferrugineus olivier

AB 723 The entomopathogenic fungus, Beauveria bassiana (Bals.) Vuill. was evaluated as a biological control agent against the red palm weevil Rhynchophorus ferrugineus (Oliv.) in United Arab Emirates and Egypt. In UAE, the fungus was studied using a local strain. For adult weevils, the calculated LC5o was 6.3x10. conidia /ml. Duration of the parasitic phase of the fungus was 9.6 days. Most of insects died between the 8th and 13th days. In the first 6 days after contamination, no symptoms were observed. In the 7th day, diseased adults appeared sluggish in their movement and the insects were unable to get up of their back. Larvae differed in their susceptibility to infection due to their age. For adults, duration of the saprophytic phase was 14.1 days and the fungus successfully developed on 81.5% of the dead insects and mycosed cadaver produced 2.12X10. conidia. For young larval instars, duration of the saprophytic phase was 6.6 days and the fungus successfully developed on 85.7% of dead larvae. Mycosed cadaver produced 4.3X10. conidia. The optimum temperature for conidia germination ranged 25-30 °C while, the optimum temperature for sporulation was 25 or 30 °c. Application of the fungus in date palm plantations by two methods caused mortalities ranged 61.5-76.1% and 52.6-63.8% in adult population in the 3rd month after application for spraying and dusting application respectively, in two successive seasons.. Reduction of infestation resulted from spraying the fungus was 29.5% , two months after treatment increased to 39.9% after six months. In the dusted block, reduction of infestation resulted from dusting was 23.9% in the two months following application, increased to reach 35.7% after six month. In Egypt, an endigenous isolate of B. bassiana isolated from red palm weevil cadaver was evaluated as a biological control agent againsr red palm weevel. Field application was conducted with the fungus against the red palm weevil at Elkassasin, Ismailia Governorate through 2007 -2008. Three methods were carried out: 1. injection of B. bassiana in naturally infested palm trees. The success of the treatment was up 90 %. 2. Periodical dusting application of fungal spores on palm trees in March and September. A reduction of palm trees infestation following field application was noticed and 3. release of contaminated males of red palm weevil with fungal spores. These methods proved considerable reduction in the palm weevil population. The results suggest that fungus.E. bassiana is a promising agent for use as bio-insecticide to control the red palm weevil