RESUMEN
Keeping honeybees healthy is essential, as bees are not only important for honey production but also cross-pollination of agricultural and horticultural crops; therefore, bees have a significant economic impact worldwide. Recently, the lethal disease, the American foulbrood (AFB), caused great losses of honeybee and decline of global apiculture. Recent studies have focused on using natural insect-derived antibiotics to overcome recently emerged AFB-resistance to conventional antibiotics. In support of these studies, here we investigate the possibility of producing bee-derived anti-AFB antibiotics from an indigenous honeybee, Apis mellifera jemenitica. The immune responses of the third instar stage were first induced against the standards Micrococcus luteus and Escherichia coli compared with the indigenous Paenibacillus larvae (ksuPL5). Data indicated a strong immune response against M. luteus, E. coli and P. larvae 24 h post-P. larvae-injection as revealed by the detection of lysozyme-like, cecropin-like and prophenoloxidase (PO) activities in the plasma of P. larvae-injected third instars. Nodulation activity against injected P. larvae as early as 4 h and peaking 48 h post-P. larvae injection were observed. Potentially active anti-P. larvae immune peptide fractions purified by high-performance liquid chromatography (HPLC) showed significant in vivo therapeutic effects on P. larvae-infected first instars. Mass spectrophotometric analysis and Orbitrap measurements of P. larvae-injected plasma indicated the expression of PO (Mr: 80 kDa), beta-1,3-glucan-binding protein (Mr: 52 kDa) and serine protease 44 isoform X1 (Mr: 46 kDa). This suggests that one or all of these immune peptides contribute to significant survivorship of P. larvae-infected broods, and could be a valuable clue in the search for honeybee-derived anti-AFB natural therapeutic agents. Further molecular characterization and description of the functional roles of these predicted antimicrobial peptides from both broods and adult honeybee may enrich the arsenal of insect-derived antibiotics of therapeutic purposes.
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BACKGROUND: The incidence of mosquito-borne diseases and the resistance of mosquitoes to conventional pesticides have recently caused a panic to the authorities in the endemic countries. This study was conducted to identify native larvicidal biopesticides against Culex pipiens for utilization in the battle against mosquito-borne diseases. METHODS: Larvicidal activities of new indigenous Bacillus thuringiensis isolates and crude toxin complexes (TCs) of two nematode bacterial-symbionts, Photorhabdus luminescens akhurstii (HRM1) and Ph. luminescens akhurstii (HS1) that tested against Cx. pipiens. B. thuringiensis isolates were recovered from different environmental samples in Saudi Arabia, and the entomopathogenic nematodes, Heterorhabditis indica (HRM1) and He. sp (HS1) were isolated from Egypt. Larvicidal activities (LC50 and LC95) of the potentially active B. thuringiensis strains or TCs were then evaluated at 24 and 48h post-treatment. RESULTS: Three B. thuringiensis isolates were almost as active as the reference B. thuringiensis israelensis (Bti-H14), and seven isolates were 1.6-5.4 times more toxic than Bti-H14. On the other hand, the TCs of the bacterial symbionts, HRM1 and HS1, showed promising larvicidal activities. HS1 showed LC50 of 2.54 folds that of HRM1 at 24h post-treatment. Moreover, histopathological examinations of the HS1-treated larvae showed deformations in midgut epithelial cells at 24h post-treatment. CONCLUSION: Synergistic activity and molecular characterization of these potentially active biocontrol agents are currently being investigated. These results may lead to the identification of eco-friend mosquito larvicidal product(s) that could contribute to the battle against mosquito-borne diseases.
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A large-scale field survey was conducted to screen major Saudi Arabian beekeeping locations for infection by Melissococcus plutonius. M. plutonius is one of the major bacterial pathogens of honeybee broods and is the causative agent of European Foulbrood disease (EFB). Larvae from samples suspected of infection were collected from different apiaries and homogenized in phosphate buffered saline (PBS). Bacteria were isolated on MYPGP agar medium. Two bacterial isolates, ksuMP7 and ksuMP9 (16S rRNA GenBank accession numbers, KX417565 and KX417566, respectively), were subjected to molecular identification using M. plutonius -specific primers, a BLAST sequence analysis revealed that the two isolates were M. plutonius with more than 98% sequence identity. The molecular detection of M. plutonius from honeybee is the first recorded incidence of this pathogen in Saudi Arabia. This study emphasizes the need for official authorities to take immediate steps toward treating and limiting the spread of this disease throughout the country.
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The present work aimed at investigating the genetic diversity of the head louse Pediculus humanus capitis (P. humanus capitis) among infested primary school girls at Bisha governorate, Saudi Arabia, based on the sequence of mitochondrial cytochrome b (mt cyt b) gene of 121 P. humanus capitis adults. Additionally, the prevalence of pediculosis capitis was surveyed. The results of sequencing were compared with the sequence of human head lice that are genotyped previously. Phylogenetic tree analysis showed the presence of 100% identity (n = 26) of louse specimens with clade A (prevalent worldwide) of the GenBank data base. Louse individuals (n = 50) showed 99.8% similarity with the same clade A reference having a single base pair difference. Also, a number of 22 louse individuals revealed 99.8% identity with clade B reference (prevalent in North and Central Americas, Europe, and Australia) with individual diversity in two base pairs. Moreover, 14 louse individual sequences revealed 99.4% identity with three base pair differences. It was concluded that moderate pediculosis (~13%) prevailed among the female students of the primary schools. It was age-and hair texture (straight or curly)-dependent. P. humanus capitis prevalence diversity is of clades A and B genotyping.
Asunto(s)
Variación Genética , Infestaciones por Piojos/parasitología , Pediculus/genética , Animales , Australia , Niño , Citocromos b/genética , Bases de Datos de Ácidos Nucleicos , Europa (Continente) , Femenino , Genotipo , Humanos , Infestaciones por Piojos/epidemiología , Pediculus/clasificación , Filogenia , Prevalencia , Arabia Saudita/epidemiología , Instituciones AcadémicasRESUMEN
Studies on the distribution of sand flies are important for the control of leishmaniasis in endemic and neighboring areas. In the present study polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) was used to identify the distribution of sand flies in Al-Madinah and Asir Regions of Saudi Arabia using PCR-RFLP of 18S ribosomal RNA gene. Based on the morphological characteristics, the sand flies were differentiated into seven species viz., Phlebotomus papatasi, Phlebotomus sergenti, Phlebotomus bergeroti, Sergentomyia clydei, Sergentomyia antennata, Sergentomyia fallax and Sergentomyia schwetzi. PCR-RFLP of 18S ribosomal RNA (rRNA) genes with eight different restriction enzymes resulted in species-specific agarose gel electrophoresis banding patterns. Of the eight restriction enzymes used, not a single restriction enzyme by itself could separate species belonging to the same genera (like P. papatasi and P. sergenti by AseI) as well as those belonging to different genera (like P. papatasi and S. clydei by AseI). We therefore conclude that the genetic diversity within sand fly species based on PCR-RFLP technique was nonspecific. Studies are in progress to study the viability of alternate techniques like low-stringency single specific primer polymerase chain reaction which can be used for molecular typing.
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Laboratory observations on the effect of Hepatozoon gracilis on the egg production of the mosquito Cx. (Cx.) pipiens Linneaus under laboratory conditions revealed that H. gracilis infected mosquitoes produced significantly fewer eggs than uninfected ones. The egg production decreased as parasite burdens increased. Reduction in blood meal size in infected females did not reduce fecundity. No size differences was detected between oocyst-infected and uninfected females although sporozoite positive females were significantly large. Preoviposition period was affected significantly, while incubation period and percentage of egg hatching showed no significant changes. The longevity of female infected mosquitoes decreased insignificantly than in uninfected ones.