Study on the pathogenesity of Metarhizium anisopliae and Beauveria bassiaia for control of the date horened beetle (Oryctes elegans)

Dates horned beetle exists in the most date palm cultivation areas. The larvae of pest is large with strong jaw that is feeding easily on petiole and tail end dates clusters and create holes on them. In this study, lethal and sublethal dose effects of fungi Beauveria bassiana, Beauveria brongniartii and Metarhizium anisopliae on the larvae and adults of pest were investigated. The larvae and adults were treated by 6 dropping method doses of any fungi including 5×107, 108, 5×108, 109, 5×109 and 1010 spors/ml to determine the lethal power. The larvae were treated by 6 injection method doses of any fungi including 105, 5×105, 106, 5×106, 107, 5×107 spors/ml and control and by 6 oral method doses of any fungi including 106, 5×106, 107, 5×107, 108, 5×108 spors/ml and control to comparison the effects of infection methods. The larvae were treatedd by 5 doses including 5×104, 105, 5×105, 106 and 5×106 to determine its sublethal effects on the power of weight growth and feeding of larvae with dropping method. The adults were treatedd by 5 doses including 105, 5×105, 106, 5×106 and 107 to determine its sublethal effects on the power of fecundity and hatching of eggs. Then treatments compared with control treatment and 50 percent lethal and sublethal doses were calculated by using Log-Probit analysis method. The 50 percent dropping method lethal doses of fungi B. bassiana, B. brongniartii and M. anisopliae were equivalent to 6.21×108, 6.13×108 and 5.55×108 spores/ml respectively. The 50 percent oral and injection method lethal doses of fungi B. bassiana, B. brongniartii and M. anisopliae were equivalent to 5.07×109, 1.05×109 and 8.17×108 and 1.08×105, 4.89×106 and 4.57×106 spores/ml respectively. Minimum and maximum sublethal doses for reduction of 50 percent fecundity were related to M. anisopliae and B. bassianai and equivalent to 5.49×103 and 3.08×104 spores/ml respectively. Minimum and maximum sublethal doses for reduction of 50 percent egg hatching were related to M. anisopliae and B. bassianai and equivalent to 5.08×102 and 1.17×104 spores/ml respectively. Minimum and maximum sublethal doses for reduction of 50 percent larvae feeding were related to M. anisopliae and B. bassiana and equivalent to 5.44×105 and 1.35×106 spores/ ml respectively. Minimum and maximum sublethal doses for reduction of 50 percent larvae weight growth were related to M. anisopliae and B. bassiana and equivalent to 2.76×105 and 4.75×105 spores/ ml respectively. The results of this study showed that the fungus M. anisopliae had the highest lethal effects and upper limiting effects fecundity, egg hatching, growth and nutrition of pest and it was the most suitable fungi for microbial control date horned beetle among the studied entomopathogenic fungi.