Isolation, Identification, and Biocontrol Potential of Entomopathogenic Nematodes and Associated Bacteria against Virachola livia (Lepidoptera: Lycaenidae) and Ectomyelois ceratoniae (Lepidoptera: Pyralidae)

(Lepidoptera: Lycaenidae) and (Lepidoptera: Pyralidae) are the key pests of pomegranates in Saudi Arabia that are managed mainly using broad-spectrum pesticides. Interactions between the entomopathogenic nematodes (EPNs) Steinernematids, and Heterorhabditids, and their entomopathogenic bacterial symbionts (EPBs) have long been considered monoxenic 2-partner associations responsible for killing insects and, therefore, are widely used in insect pest biocontrol. However, there are limited reports identifying such organisms in Taif, Saudi Arabia. The current study aimed to identify the EPNs and their associated bacteria isolated from Taif, Saudi Arabia, and evaluate their biocontrol potential on third instar larvae of and under laboratory conditions. A total of 35 EPN isolates belonging to (20) and (15) were recovered from 320 soil samples. Twenty-six isolates of symbiotic or associated bacteria were isolated from EPNs and molecularly identified as (6 isolates), (4 isolates), (7), or (9). A pathogenicity assay revealed that spp. were more virulent than spp. against the two pomegranate insects, with LC values of 18.5 and 13.6 infective juveniles (IJs)/larva of for spp. and 52 and 32.4 IJs/larva of for spp. at 48 and 72 h post-treatment, respectively. Moreover, LC values of 9 and 6.6 IJs/larva ( spp.) and 34.4 and 26.6 IJs/larva ( spp.) were recorded for larvae at 48 and 72 h post-treatment. In addition, the EPB CQ1, isolated from spp., surpassed SJ10, associated with spp., in their ability to kill or larvae within 6 h post-application, resulting in 100% mortality in both insects after 24 and 48 h of exposure. We conclude that either application of EPNs' IJs or their associated EPBs could serve as potential biocontrol agents for and .