First Report of Spirocerca Lupi Larva in Dung Beetles (Scarabaeus Armeniacus) in Iran: A Morphological and Molecular Identification

Abstract Background: Dung beetles are detritivores insects. They naturally use feces of vertebrates as foods and reproduction beds. This leads to frequent contacts between dung beetles and parasitic helminths. The current study was carried out to assess infections of dung beetles with larval stages of helminths in rural areas of Taleqan County, Alborz Province, Iran. In total, 200 dung beetles were randomly collected in June 2017 from the highlands of Taleqan County. Beetles were dissected in normal saline and carefully studied using stereomicroscopy. Morphological characteristics of the recovered larvae were drawn using camera lucida equipped microscope at 400× magnification. Furthermore, genomic DNAs of the recovered larvae were extracted and PCR amplifications of the mitochondrial cytochrome c oxidase subunit 1 (cox1) genes were carried out and the amplicons were sequenced. Results: All collected dung beetles were identified as Scarabaeus armeniacus from Scarabaeidae family (55.5% were male and 44.5% female). Three females of the beetles were infected with nematode larva, morphologically identified as the third-stage of Spirocerca lupi larvae. The average length and width of the larvae were 2.95 (2.81–3.15; CI 95%) and 0.12 (0.1–0.15; CI 95%) mm, respectively. The phylogenetic analysis showed that S. lupi belonged to a clade within Spirocercidae family, well separated from Onchocercidae family. Conclusions: In the current study, S. armeniacus was introduced as a potentially biological vector for the transmission of S. lupi to vertebrates in the region. To the best of the authors’ knowledge, this is the first reported on larval stages of S. lupi in S. armeniacus.