مشخصات پژوهش

Chemical pesticides have harmful effects on the environment and non-target organisms, prompting the search for safer alternatives such as microbial biopesticides. Actinomycetes species, known for producing bioactive compounds, were explored for their biocidal potential. In this research a total of 48 Actinomycetes isolates were obtained from the gastrointestinal tracts of desert lizards in Qom, Iran. Using 16S rRNA gene sequencing, 31 isolates were identified as Streptomyces, with the remaining belonging to rare genera, including Kribbella, Micrococcus, Nonomuraea, Saccharothrix, Nocardia, Micromonospora, and Actinomadura. Bioactivity assays revealed that 41 isolates were toxic to Artemia urmiana nauplii. The four most toxic Streptomyces isolates (UTMC 3304, 3527, 3534, and 3285) were tested for pesticidal properties against three plant pests: Tetranychus urticae, Metopolophium dirhodum, and Chaitophorus salijaponicus niger. UTMC 3304 was most potent against T. urticae, with the lowest LC50 (20.6 mg/ml) and fastest mortality (LT50 = 2.7 hours). UTMC 3534 showed the highest efficacy against M. dirhodum (LC50 = 16.9 mg/ml, LT50 = 3 hours). Conversely, UTMC 3527 exhibited the least effectiveness with higher LC50 value (49.6 mg/ml) and slower mortality rate (LT50 = 8.9–13.4 hours). GC-MS analysis identified several volatile compounds, including alkanes, fatty acids, terpenoids, and phthalic acid esters, known for their pesticidal properties. These results highlight the potential of these isolates, especially the most toxic Streptomyces strains, as microbial control agents for the targeted pests.