Yahya Al Naggar
Dr. Al Naggar has a full-time position as associate professor at zoology department, faculty of science, Tanta University, Egypt. He got his PhD from Saskatchewan University, Canada under supervision of prof. John Giesy at Toxicology center in 2015 (Joint Supervision with Tanta University). He finished his 1st postdoc fellowship at Entomology Department, University of California at Riverside, USA (July-December 2018). Currently, he is Alexander von Humboldt postdoc research scientist at institute of General Biology, Martin Luther University, Germany.
Since 2015, he participated in supervision committees of two master and two PhD students in Egypt and in Germany with projects addressing effects of metal nanoparticles and pesticides singly or in combination with other environmental stressors on living organisms (mainly bees, mosquitoes, and Drosophila) and its long-term effects on the environment. He has a continuous record of publications (28) in quality journals in the fields of ecology, ecotoxicology and nanotoxicology. Currently, he is also a reviewer for several highly ranked, peer-reviewed journals and for some funding agencies such as STDF in Egypt, ANR in France and the Millennium Science Initiative in Chile. As reward to his hard work, he has been awarded the scientific publication award several times from Tanta University. In 2016, he also received the gold medal for best oral presentation at the 13th Asian Apicultural Association Conference Jeddah, Kingdom of Saudi Arabia.
Phone: +201016611092
Address: Zoology Department, Faculty of Science, Tanta University,31527, Egypt.
Since 2015, he participated in supervision committees of two master and two PhD students in Egypt and in Germany with projects addressing effects of metal nanoparticles and pesticides singly or in combination with other environmental stressors on living organisms (mainly bees, mosquitoes, and Drosophila) and its long-term effects on the environment. He has a continuous record of publications (28) in quality journals in the fields of ecology, ecotoxicology and nanotoxicology. Currently, he is also a reviewer for several highly ranked, peer-reviewed journals and for some funding agencies such as STDF in Egypt, ANR in France and the Millennium Science Initiative in Chile. As reward to his hard work, he has been awarded the scientific publication award several times from Tanta University. In 2016, he also received the gold medal for best oral presentation at the 13th Asian Apicultural Association Conference Jeddah, Kingdom of Saudi Arabia.
Phone: +201016611092
Address: Zoology Department, Faculty of Science, Tanta University,31527, Egypt.
less
InterestsView All (16)
Uploads
Papers by Yahya Al Naggar
Percentages of incidence of apoptosis or/and necrosis in mid gut cells were also quantified by use of flowcytometry. Rapture of the peritrophic
membrane (PM)was among the most observed histopathological alteration in bees fed sugar syrup contained CdO NPs separately or combined with PbO NPs. Common cytological alterations observed
in epithelial cellswere irregular distribution or/and condensation of nuclear chromatin,mitochondrial swelling and lysis, and rough endoplasmic reticulum (rER) dilation, fragmentation, and vesiculation and were quite similar in all treated groups compared to control. The greatest incidence (%) of necrosis was observed in bees fed the diet that contained CdO NPs alone. The greatest % of both apoptosis and necrosis was observed in bees fed sugar syrup spiked with sublethal concentrations of both metal oxide NPs. Joint action of the binary mixture of Cd and Pb oxide NPs on honey bees was concluded to be antagonistic. Collectively, exposure of honey bees to these metal oxide NPs even at sublethal concentrations will adversely affect viability of the colony and further studies are still required to determine the effects of thesemetal oxide NPs on behavior and pollination ecology of honeybees.
attention of stakeholders and decision makers to the value of pollinators in terms of the sustainability of agricultural production in Egypt.
present study, effects of exposure to sublethal concentrations of PbO and CdO NPs, either separately or in combination on honey bee (A. mellifera) workers were
assessed. Honey bee workers were fed sugar syrup contained (20 % of LC50) of CdO (0.01 mg ml-1) and PbO (0.65 mg ml-1) NPs either separately or combined for nine days under laboratory conditions. Control bees were fed 1.5 M sucrose syrup without NPs. Effects on histological and cellular structure of mid gut cells were investigated using light and electron microscope. Percentages of incidence of apoptosis or/and necrosis in mid gut cells were also quantified by use of flow cytometry. Rapture of the peritrophic membrane (PM) was among the most observed histopathological
alteration in bees fed sugar syrup contained CdO NPs separately or combined with PbO NPs. Common cytological alterations observed in epithelial cells were irregular distribution or/and condensation of nuclear chromatin, mitochondrial swelling and lysis, and rough endoplasmic reticulum (rER) dilation, fragmentation, and
vesiculation and were quite similar in all treated groups compared to control. The greatest incidence (%) of necrosis was observed in bees fed the diet that contained CdO NPs alone. The greatest % of both apoptosis and necrosis was observed in bees
fed sugar syrup spiked with sublethal concentrations of both metal oxide NPs. Joint action of the binary mixture of Cd and Pb oxide NPs on honey bees was concluded to be antagonistic. Collectively, exposure of honey bees to these metal oxide NPs even at sublethal concentrations will adversely affect viability of the colony and furtherstudies are still required to determine the effects of these metal oxide NPs on behavior
and pollination ecology of honeybees.
exposure to organophosphate and neonicotinoid plant protection
products on the European honey bee (Apis mellifera L.) in Egypt
were investigated. Using concentrations reported in those studies,
an assessment of hazards posed by these two classes of insecticides
to humans due to consumption of Egyptian honey from the Nile
Delta during both spring and summer was performed. Twenty-eight
compounds including metabolites were assessed for exposure of
adult Egyptians based on the best- and worst-case scenarios. Even
for the worst-case scenario, exposure to these two classes of
pesticides in honey was 15-fold less than hazard index value of 1.0
for adverse effects on humans. Based upon this analysis, people
exposed to these insecticides through consumption of honey
products would be unlikely to exhibit adverse health outcomes.
activities of propolis were confirmed by use of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and by using Nrf2 Luciferase reporter cell lines. The three EEPs exhibited strong scavenging of free radicals, and protective activity against oxidative stress caused by exposure to H2O2 in this in vitro system. These results support the use of propolis from these regions of Canada as a source of natural antioxidants.
of treatment with miticides was further evaluated by monitoring both viral load and rate of indoor overwintering
survival of colonies of European honey bees (Apis mellifera L.) in the vicinity of Saskatoon, Saskatchewan, Canada.
Forty-five colonies were randomly assigned to three treatment groups with 15 hives per group: Group 1; 2 strips of
Thymovar (thymol); Group 2; 2 strips of Apivar (Amitraz); and Group 3; no treatment (control). Significant
decreases in the rates of colony infestation (Mites per hundred bees, MPHB) by V. destructor were observed (p < 0.05)
between colonies of bees treated with Apivar in October 2013 when compared to control colonies. Efficacy of
Apivar and Thymovar against V. destructor after treatment for 22 days were 76.5 and 26.7%, respectively. After
22 days, concentrations of the two miticides in bees were 15.4 ng amitraz/g wet mass (wm) and 64,800 ng thymol/g
wm. There were no significant differences (p > 0.05) in the percentage of colonies infected by deformed wing virus
(DWV) and Israeli acute paralysis virus (IAPV) either before or after treatment with Apivar or Thymovar in
October 2013 and 7 months post treatment in April 2014. Only the Apivar treatment group showed IAPV infections
in April 2014. The group treated with Apivar exhibited a better overwintering rate of survival (93%), than hives
treated with Thymovar (67%). These results suggest volatile miticides like Thymovar should be avoided in
geographical areas with colder fall temperatures.
Percentages of incidence of apoptosis or/and necrosis in mid gut cells were also quantified by use of flowcytometry. Rapture of the peritrophic
membrane (PM)was among the most observed histopathological alteration in bees fed sugar syrup contained CdO NPs separately or combined with PbO NPs. Common cytological alterations observed
in epithelial cellswere irregular distribution or/and condensation of nuclear chromatin,mitochondrial swelling and lysis, and rough endoplasmic reticulum (rER) dilation, fragmentation, and vesiculation and were quite similar in all treated groups compared to control. The greatest incidence (%) of necrosis was observed in bees fed the diet that contained CdO NPs alone. The greatest % of both apoptosis and necrosis was observed in bees fed sugar syrup spiked with sublethal concentrations of both metal oxide NPs. Joint action of the binary mixture of Cd and Pb oxide NPs on honey bees was concluded to be antagonistic. Collectively, exposure of honey bees to these metal oxide NPs even at sublethal concentrations will adversely affect viability of the colony and further studies are still required to determine the effects of thesemetal oxide NPs on behavior and pollination ecology of honeybees.
attention of stakeholders and decision makers to the value of pollinators in terms of the sustainability of agricultural production in Egypt.
present study, effects of exposure to sublethal concentrations of PbO and CdO NPs, either separately or in combination on honey bee (A. mellifera) workers were
assessed. Honey bee workers were fed sugar syrup contained (20 % of LC50) of CdO (0.01 mg ml-1) and PbO (0.65 mg ml-1) NPs either separately or combined for nine days under laboratory conditions. Control bees were fed 1.5 M sucrose syrup without NPs. Effects on histological and cellular structure of mid gut cells were investigated using light and electron microscope. Percentages of incidence of apoptosis or/and necrosis in mid gut cells were also quantified by use of flow cytometry. Rapture of the peritrophic membrane (PM) was among the most observed histopathological
alteration in bees fed sugar syrup contained CdO NPs separately or combined with PbO NPs. Common cytological alterations observed in epithelial cells were irregular distribution or/and condensation of nuclear chromatin, mitochondrial swelling and lysis, and rough endoplasmic reticulum (rER) dilation, fragmentation, and
vesiculation and were quite similar in all treated groups compared to control. The greatest incidence (%) of necrosis was observed in bees fed the diet that contained CdO NPs alone. The greatest % of both apoptosis and necrosis was observed in bees
fed sugar syrup spiked with sublethal concentrations of both metal oxide NPs. Joint action of the binary mixture of Cd and Pb oxide NPs on honey bees was concluded to be antagonistic. Collectively, exposure of honey bees to these metal oxide NPs even at sublethal concentrations will adversely affect viability of the colony and furtherstudies are still required to determine the effects of these metal oxide NPs on behavior
and pollination ecology of honeybees.
exposure to organophosphate and neonicotinoid plant protection
products on the European honey bee (Apis mellifera L.) in Egypt
were investigated. Using concentrations reported in those studies,
an assessment of hazards posed by these two classes of insecticides
to humans due to consumption of Egyptian honey from the Nile
Delta during both spring and summer was performed. Twenty-eight
compounds including metabolites were assessed for exposure of
adult Egyptians based on the best- and worst-case scenarios. Even
for the worst-case scenario, exposure to these two classes of
pesticides in honey was 15-fold less than hazard index value of 1.0
for adverse effects on humans. Based upon this analysis, people
exposed to these insecticides through consumption of honey
products would be unlikely to exhibit adverse health outcomes.
activities of propolis were confirmed by use of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and by using Nrf2 Luciferase reporter cell lines. The three EEPs exhibited strong scavenging of free radicals, and protective activity against oxidative stress caused by exposure to H2O2 in this in vitro system. These results support the use of propolis from these regions of Canada as a source of natural antioxidants.
of treatment with miticides was further evaluated by monitoring both viral load and rate of indoor overwintering
survival of colonies of European honey bees (Apis mellifera L.) in the vicinity of Saskatoon, Saskatchewan, Canada.
Forty-five colonies were randomly assigned to three treatment groups with 15 hives per group: Group 1; 2 strips of
Thymovar (thymol); Group 2; 2 strips of Apivar (Amitraz); and Group 3; no treatment (control). Significant
decreases in the rates of colony infestation (Mites per hundred bees, MPHB) by V. destructor were observed (p < 0.05)
between colonies of bees treated with Apivar in October 2013 when compared to control colonies. Efficacy of
Apivar and Thymovar against V. destructor after treatment for 22 days were 76.5 and 26.7%, respectively. After
22 days, concentrations of the two miticides in bees were 15.4 ng amitraz/g wet mass (wm) and 64,800 ng thymol/g
wm. There were no significant differences (p > 0.05) in the percentage of colonies infected by deformed wing virus
(DWV) and Israeli acute paralysis virus (IAPV) either before or after treatment with Apivar or Thymovar in
October 2013 and 7 months post treatment in April 2014. Only the Apivar treatment group showed IAPV infections
in April 2014. The group treated with Apivar exhibited a better overwintering rate of survival (93%), than hives
treated with Thymovar (67%). These results suggest volatile miticides like Thymovar should be avoided in
geographical areas with colder fall temperatures.