Promising Algerian essential oils as natural acaricides against the honey bee mite Varroa destructor (Acari: Varroidae).

Varroosis induced by Varroa destructor Anderson and Trueman represents the most pathogenic and destructive disease affecting the western honey bee, Apis mellifera. In this study, we investigated the acaricidal activity against the Varroa mite using essential oils (EOs) from the aerial parts of four autochthonous Algerian herbal species, namely Artemisia herba alba, Artemisia campestris, Artemisia judaica and Ruta montana. EOs were obtained by means of hydrodistillation and their composition was characterized by gas chromatography-mass spectrometry. The toxicity of the selected EOs toward V. destructor and A. mellifera adult honey bees was evaluated using the complete exposure method. The results indicate the predominance of davanone (66.9%) in A. herba alba, ß-pinene (19.5%) in A. campestris, piperitone (68.7%) in A. judaica and 2-undecanone (70.1%) in R. montana EOs. Interestingly, the LC50 values coupled to bee mortality rates revealed that all tested oils exhibited significant acaricidal efficiency with selectivity ratio (SR) values of 10.77, 8.78, 5.62 and 3.73 for A. campestris, A. judaica, A. herba alba, and R. montana, respectively. These values were better than that of thymol (SR = 3.65), the positive control. These findings suggest that these EOs could be used as plant-derived veterinary acaricides to control varroosis in field conditions.

Effects of Pollen Deprivation in Groups of Tellian (Apis mellifera intermissa) and Saharan (Apis mellifera sahariensis) Honey Bees under Controlled Conditions.

Worldwide, honey bees are increasingly faced with periods of pollen scarcity, which can lead to nutritional deficiencies, especially of proteins and amino acids. These are essential for the proper functioning of the single organism and the colony. To understand how bees react to protein deficiency, under controlled conditions, we studied the effect of pollen deficiency on the main physiological parameters in two subspecies endemic of Algeria, Apis mellifera intermissa and Apismellifera sahariensis. Emerging workers of both subspecies were reared with two diets: one was pollen-fed, whereas the other pollen-deprived. Several physiological criteria were measured depending on the type of diet and subspecies: the survival of the bees, the amount of total protein in the hemolymph, hypopharyngeal glands development and the ovary development of workers. These last three parameters were assessed at three different ages (7, 14 and 21 days). At birth, sahariensis workers weighed more than intermissa. With the same protein diet, the average life expectancy of sahariensis was extended by 5.55 days compared to intermissa. Even if deprived of pollen, sahariensis lived longer than intermissa fed with pollen (p < 0.001). In the three age levels, the hypopharyngeal glands were more developed and less affected by pollen deficiency (p < 0.001) in sahariensis than in intermissa (p < 0.001). The total hemolymph protein was higher in intermissa than in sahariensis regardless of the diet, and was also higher in protein-fed than in deprived bees (p < 0.001). The ovaries developed more rapidly with a high proportion in intermissa than in sahariensis (p < 0.05) regardless of the diet, and was also higher in the bees fed with pollen than those deprived (p < 0.05). Pollen deficiency generates physiological alterations and modifications, the amplitude of which varied according to the subspecies of the bee studied.