Secondary invader bacteria associated with the red pest weevil infestation in date palm trees

Abstract

The worldwide loss of date palm (Phoenix dactylifera L.) productivity is due to the infestation of the red pest weevil (RPW). The pest makes tunnels in the tree trunk and could be followed by secondary microbial infections causing oozing of fluid with a distinct fermentation odor. This study aimed at isolation and identification of secondary invader bacteria associated with the RPW and confirmation of their potential destructive effect on the tree. Four bacterial isolates were recovered from the infested date palm tissues, and they were identified based on phenotypic characteristics using the VITEK2 system. Three out of the four isolates were identified as Pseudomonas aeruginosa, and one isolate was identified as Burkholderia cepacia. All isolates caused rot of date palm germinated seeds (up to 40%), and wilt and root rot of date palm seedlings (40-100%). Pseudomonas aeruginosa (isolate No. 3) was the most aggressive isolate that involved 40% mortality and caused 100% of root rot incidence in date palm seedlings. Burkholderia cepacia showed the lowest degree of rot on the germinated seeds, percentage mortality, percentage root rot incidence of date palm seedlings. Pseudomonas aeruginosa (isolate No. 1) and B. cepacia caused a high loss in the weight of date palm petioles tissues (about 10%). The study threw light on the detrimental effects of secondary invader microbes associated with the RPW infestation. The study recommended an application of an integrated management program containing both antibacterial and insecticidal preparation in the management of the RPW to avoid a further negative effect on the palm trees.Abbreviations: NA, nutrient agar; RPW, red pest weevil.