Abstract
The present study was conducted at three plots of young date palm trees, located 80 km in the North-Western area of Almadinah Almounawwarah, Kingdom of Saudi Arabia (KSA), where date palm cultivars suffer from the infestation with the root borer, Lucanus cervus (L.) (Coleoptera: Lucanidae). Larvae cause a tree loss, ranging from 72 to 12%, depending on the plot site and the cultivar. In a trial to control the insect pest, three biological materials were tested in vitro and in vivo against the larvae namely; the neem oil, metabeave (Beauveria powder) and the fungus Trichoderma viride. The larvicidal activity (LC50 and LC90) of metabeave powder (128 and 512 ppm, respectively) was more significant than that of the neem oil (240 and 960 ppm, respectively). In an attempt to explain the possible role exerted by the bio-agents in protein assimilation, the hemolymph of the larvae was analyzed using SDS-PAGE, where quantitative and qualitative changes were clearly observed in the bands of protein patterns in treated larvae as compared to the untreated ones. These changes may account to specific protease inhibitors of the tested bio-agents that affect protein degradation in the gut. Application of combined activity of the three bio-control agents induced a marked decrease in the further loss of the different cultivars recording 31 to 6%.