SURVEY OF RHINOCEROS BEETLE, Oryctes SPP. (COLEOPTERA: SCARABAEIDAE), IN ITS MICROBIAL IN DATE PALM ORCHARDS IN AL-MADINAH ALMUNWARAH REGION

Abstract

The Incidence and microbial natural enemies of Oryctes spp. (Coleoptera: Scarabaeidae) in date palm orchards in Al-madinah Almunwarah region, were studied. The different date palm cultivars can be arranged in descending order according to the infestation severity with Oryctes spp. as follow: Ajwah > Rothan > Safawi > Helwah > Shalabi > Barni and Rabbiah. The highest infestation rates of date palms with rhinoceros beetles were reached 44.1, 42.2 and 37.7% in September, August and November respectively. Whereas, the lowest infestation was recorded in February (10.2%) and January (11.7%). The population density decreased to reach the minimum values by mid January. The dominant stage of development occurred was the third larval instar. The first and second instars were rarely encountered. The vertical distribution of adults and immatures of the rhinoceros beetle around the heaps and root of the date palm was also studied. Data revealed that adults were more abundant in the surface layer at depth of 0:30 cm than immatures. While, immature stages were the most dominant at 30-60 cm depth. There were 72.3% of immatures (larvae and pupae) population found in the middle layer at depth (30:60 cm) around roots. In comparison, the third depth layer included only 5.3 % adults and 16.3% immatures. Four microbial natural enemies were recorded as mortality factors associated with the larval and pupal stages sampled within date palm orchards. The microbial analysis was narrowed down to detect only entomopathogenic fungi (Beauveria bassiana and Metarhizium anisopliae), bacteria (Bacillus spp.), and virus (Oryctes virus). Entomopathogenic fungi caused average mortality to Oryctes larval population reached 15.3% and 9.2% by Beauveria bassiana and Metarhizium anisopliae, respectively. In comparison both entomopathogenic fungi caused 6.5% pupal mortality. On the other hand, Bacillus spp. caused the highest larval mortality reaching up to 39.2%, compared to 3.3% to pupae. Whereas, the percentage of infected larvae and pupae with virus recorded 27.6% and 11.5%, respectively and it was higher than of both pathogenic fungi (24.5%).