الفهرس 
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Abstract
The present work was conducted to study the efficacy of flonicamid and pymetrozine on aphids, their safety on honeybee insects and comparing them to some neonicotinoids. It was also conducted with the aim of studying some of the effects and physiological changes that occur in honeybee insects after exposure to imidacloprid.
The results obtained in this study can be summarized as follows:
6.1. Toxicity of tested neonicotinoids and alternatives on Aphis craccivora and Apis mellifera.
Clothianidin showed high efficacy against the legume (cowpea) aphid, Aphis craccivora (LC50 = 0.016 ppm) followed by flonicamid and pymetrozine (LC50 = 1.23 and 3.17 ppm, respectively) and imidacloprid (LC50 = 9.5 ppm). Clothianidin showed high toxicity to honeybee insects (LC50 = 0.033ppm) followed by imidacloprid (LC50 = 2.9 ppm), while alternatives proved relatively safe on honeybees (LC50 = >100 ppm).
6.2. Biological studies in Apis mellifera and Aphis craccivora following exposure to imidacloprid.
6.2.1. Determination of AChE activity in treated Apis mellifera and Aphis craccivora.
6.2.1.1. Experiments in vivo
Honeybees were exposed for 4 and 48 hours to different concentrations of the imidacloprid, the results showed an increased inhibition of enzyme activity with increasing concentrations.
When honeybees were exposed for 4 hours to the highest concentration of the imidacloprid (6.3 ppm) and then fed for different periods on sucrose solution without imidacloprid, the results showed that, enzyme activity recovered again by 88% after 24 hours of feeding on sucrose solution.
When cowpea aphids were exposed to different concentrations of the imidacloprid, enzyme activity was not affected by an increase in the concentration of the imidacloprid.
6.2.1.2. Experiments in vitro.
After extracting the enzyme from both insects and treating with different concentrations of the imidacloprid inside laboratory, the results showed that there was an inhibition of enzyme activity in the two insects in laboratory, and unlike in vivo experiments for aphids, the inhibition of enzyme activity in aphids was higher than its inhibition in honeybees, IC50 = 108.64 and 719.06 ppm, respectively.
6.2.2. Gene expression of AChE-2 in honeybees, Apis mellifera.
After treating honeybees for 4 hours with 3 concentrations of imidacloprid (0.35, 3.5 and 6.3 ppm) the results obtained in the treated honeybees at the lowest concentration were an increase in gene expression of the AChE-2 gene but not significant compared to the control, while in the treated bees at higher concentrations, the gene expression of the AChE-2 gene decreased, especially in the high concentration (6.3 ppm).
6.2.3. Determination of glutathione S-transferase (GST) activity in Apis mellifera treated with the imidacloprid.
6.2.3.1. Effect of imidacloprid at different concentrations on GST activity in vivo
After exposing honeybees for 4 hours to different concentrations of imidacloprid, the results showed an increase in the activity of GST enzyme with increasing concentration, at the highest concentration (6.3 ppm) GST activity was 107.50%.
6.2.3.2. Effect of imidacloprid exposure periods on GST activity.
After exposure of honeybees for different periods to the lowest concentration of imidacloprid (0.35 ppm) the results indicated a decrease in GST activity with an increase the period of exposure to imidacloprid. After 24 hours of exposure to the lowest concentration of imidacloprid, GST activity was 87.20%.
6.2.3.3. Effect of imidacloprid on GST activity in vitro
After extracting the enzyme from the honeybees and treated it in different concentrations inside the laboratory, the results indicated an increase in the inhibition of the enzyme by increasing the concentration of the imidacloprid.
6.3. Molecular modeling
The results showed a significant similarity in the composition of the AChE enzyme in honeybees, Apis mellifera and cowpea aphids, Aphis craccivora and therefore the places of attachment of the imidacloprid to the enzyme are very similar in the two insects. While the structure of nAChR receptors is different in both insects, the places of binding of the imidacloprid to the receptors are different in the two insects.