الفهرس 
Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Oestridae family is one of the most important three families of order Diptera, involved in veterinary diseases such as myiases. All fly species in this family are myiasis-causing endoparasites of mammals. In Egypt, Oestridae has been reported in three subfamilies: Oestrinae, Hypodermatinae, and Gasterophiliae. For Oestrinae, it is represented by three species in three different genera: the camel bot fly Cephalopina titillator (Clark, 1816), the sheep bot fly Oestrus ovis (Linnaeus, 1758), and the horse nasal bot fly Rhinoestrus purpureus (Brauer, 1858).
Cephalopina titillator is a nasal myiasis-producing parasite of camels in Egypt and worldwide. Currently, little is known about its ecology, biology, species composition and phylogenetics in Egypt. Therefore, the aim of this study was to investigate the effect of the environmental conditions on their infestation rate, seasonal variations, as well as the rate of pupation and adult emergence under laboratory conditions.
The second and third larval instars were collected from the nasopharyngeal cavities of camel heads through post-mortem inspection in El- Bassatin abattoir, Cairo, Egypt, during a 12-month period from June 2019 to May 2020. Some of the collected 3rd instar larvae were left to grow to the adult stage for adult examination and inspection of sexual dimorphism characters.
The monthly collection results showed that out of 62 dissected camel heads 33 (53.23%) of them were infested with different larval instars of C. titillator with a total of 429 larvae. The highest camel infestation rate (80%) was recorded in November and December 2019 and February 2020, while the lowest infestation rate (20%) was recorded in July 2019. The prevalence and abundance results of these flies showed a negatively correlated relationship between the rate of infestation and ambient temperature.
In this study, morphological characterization of adult fly, second and third larval instars of C. titillator was demonstrated using both the light and scanning electron microscopes (SEM). The structures of cephalic region with its accompanied mouth hooks, thoracic and abdominal spines and terminal abdominal segment of second and third instars were investigated. Moreover, morphological similarities and differences between second and third instar larvae were also reported in this work.
For molecular identification, differentiation of species, and elucidating the phylogenetic relationships of the targeted C. titillator, two molecular DNA markers were used. The first is the mitochondrial cytochrome oxidase subunit I (COI) and the second is the nuclear 28S ribosomal RNA (28S rRNA) gene sequences. The primers were custom designed for the COI from its available reference whole mitochondrial genome deposited on the National Center for Biotechnology Information (NCBI) GenBank. The 28S rRNA primers were retrieved from a relative species (O. ovis) as it is the first time to use this gene for C. titillator.
The COI-specific primer set flanked and amplified an amplicon of approximately 916 bp on PCR gels. The 28S rRNA-specific primer set spans the D1 and D2 expansion regions of the gene and amplified a region of approximately 830 bp on PCR gels. All amplification of target gene sequence fragments were carried out by polymerase chain reaction (PCR) conditions specific for each gene of collected 3rd larval instars.
The results showed that the 10 individual samples of C. titillator used were successfully amplified for each marker. No intraspecific differences in their length were observed indicating the absence of any apparent fragment size variations that assist in their divergence.
The ML phylogenetic trees were constructed to assess the evolutionary history for Oestridae family using both the mitochondrial and nuclear markers COI and 28S rRNA, respectively. The addition of the sequence for C. titillator changed the tree topology and therefore different inferences can be obtained evolutionary, especially for subfamily Oestrinae. The results for the COI gene revealed the polyphyletic relationship of Oestrinae subfamily where there is no recent common ancestor included.
Although the data for constructing 28S rRNA phylogenetic tree is limited, it showed the monophyletic relationship governing subfamily Cuterebrinae. The species of C. titillator in this study were the only samples to represent the subfamily Oestrinae in an independent branch, however, it showed a polyphyletic relationship with Gasterophilus intestinalis of subfamily Gasterophilinae.