Experiments were performed investigating citronella (Cymbopogon winterianus Jowitt) as a repellent to honeybee Apis mellifera (L.) (Hymenoptera: Apidae) in Egypt, it was conducted in laboratory in the Department of Entomology and Pesticides Science, Faculty of Agriculture, Cairo University, to check long-term survival of honeybee when exposed to different nano insecticides alone or combined with citronella at the same examination box for each. In this study, we used a modeling approach regarding survival data of caged worker bees under chronic exposure to four insecticides (Chloropyrophos, Nano-chloropyrophos Imidacloprid, Nano-Imidacloprid) each of them was supplemented in a box alone and in combination with citronella. Having three replicates and five concentrations (100, 200, 300, 400 and 500 ppm). Laboratory bioassay of these insecticides showed that chloropyrophos and nano chloropyrophos were the most toxic at their high dose (500 ppm) with LT50 of 120.98 and 122.02 followed by 132.14 and 136.5 minutes for Imidacloprid and Nano-Imidacloprid, respectively. No consumption occurred by bees to mixed sugar syrup with insecticides in all treatments when citronella was added. These data highly recommended that adding citronella is very effective when nicotinoid pesticides are used to longevity honeybee life and keep bee safe.

and summer seasons of 2015 to study the spatial distribution of young and old honeybee drones Apis mellifera L.. The obtained results showed that the spatial distribution of drones was differed according to their ages and seasons of the year. Generally the immature adult drones tend to concentrate on the brood combs, whereas the mature ones were showed on peripheral combs. On the other hand during the cold months the majority of young drones were showed on the central combs, whereas the stable temperature which was suitable for their sexual maturity.

No abstract

Pesticide application can have an adverse effect on pollinator honey bees, Apis mellifera L., ranging from mortality to sublethal effects. Therefore, it is necessary to understand any potential effects of pesticides. The present study reports the acute toxicity and adverse effects of sulfoxaflor insecticide on the biochemical activity and histological changes on A. mellifera. The results showed that after 48 h post-treatment, the LD25 and LD50 values were 0.078 and 0.162 µg/bee, respectively, of sulfoxaflor on A. mellifera. The detoxification enzyme activity shows an increase of glutathione-S-transferase (GST) enzyme on A. mellifera in response to sulfoxaflor at LD50 value. Conversely, no significant differences were found in mixed-function oxidation (MFO) activity. In addition, after 4 h of sulfoxaflor exposure, the brains of treated bees showed nuclear pyknosis and degeneration in some cells, which evolved to mushroom shaped tissue losses, mainly neurons replaced by vacuoles after 48 h. There was a slight effect on secretory vesicles in the hypopharyngeal gland after 4 h of exposure. After 48 h, the vacuolar cytoplasm and basophilic pyknotic nuclei were lost in the atrophied acini. After exposure to sulfoxaflor, the midgut of A. mellifera workers showed histological changes in epithelial cells. These findings of the present study showed that sulfoxaflor could have an adverse effect on A. mellifera.