Some essential oils as potential control agents for varroa mite (Varroa destructor) in infected honey bees (Apis mellifera).

Background: Ecto-parasite, varroa mite, (Varroa destructor), is the primary pest affecting the apiculture sector globally in various regions. Aim: This study examined the toxicity of nine essential oils to Apis mellifera L. and the acaricidal impact of those oils against V. destructor. Methods: The acaricidal effects of nine essential oils, extracted from plant materials were used. In the screening experiment, 10 mg of the active ingredients of the plant material extracts were prepared in an alcohol solution with concentrations of 5%, 10%, and 15%. For each type of plant extract, five female V. destructor were transferred to a Petri dish with five worker bees incubated at 70% humidity and 33°-34° for 2 days, for each treatment four replicates were used compared to the control. Forty-eight hours following treatment, the number of dead and live mites was counted to determine the mortality rate. In the second assay experiment, the best five essential oils of the previous experiment were selected to re-assess their effectiveness on varroa mites and honeybee workers by using a concentration of 15%. Five females of V. destructor were transferred to a Petri dish with 10 adult bees and treated with the solution of the selected oils. Five replicates and control treatments were taken for each sample simultaneously. Dead and live bees were counted for each replicate at 48 hours after treatment. Results: There were no significant differences between the concentrations used of each oil on the rate of death of mites, and its effectiveness ranged between 70.0% and 53.3% compared to the control groups. In addition, the best oil used was bitter melon, with a death rate of 80% at a concentration of 15%, while peppermint oil showed the lowest death rate of 45% at a concentration of (5%). However, all these treatments were statistically highly significant compared with the natural death rate in control (2%). In the second test, the results of the statistical analysis indicated that there were highly significant differences (P0.05 <0.0001) in the average numbers of dead varroa mites compared to the control when using a 15% concentration of five selected oils. On the other hand, there was no statistically significant difference in the honey bee workers' mortality rate between the treatment and control groups (P0.05 <0.3390), and it was relatively low for all treatments except the basil oil, where the bee mortality rate was 16% compared to the control (10%). Conclusion: It is clear from this experiment that bitter melon oil can be used to control varroa mites and it can be considered safe for honey bees as well as for the environment.

Prevalence of Varroa mites (Varroa destructor Anderson & Trueman) and bee lice (Bruala coeca Nitzsch) in honey bee (Apis mellifera L.) colonies in Libya.

Background: Primary key pest affecting the apiculture business in many areas of the globe is the ecto parasite Varroa mite (Varroa destructor), recently, bee lice have become a considerable bee pest. Aim: In this study, the ecto parasites that infest honey bees, were investigated during the spring of 2013. Methods: A total of 66 apiaries were investigated from different geographical regions in Libya: 34 apiaries from the southern region, 21 apiaries from the north-eastern region, and 11 apiaries from the north-western region. Three bee colonies were randomly chosen from each apiary (316 colonies). From each colony, 300 worker bees were taken as samples, put in container filled with 100 ml of alcohol, and transported to the Honey bee Laboratory-Plant Protection Department at the University of Tripoli's. The parasites were separated from the bees and identified, and the infestation rates were calculated. Results: The study of the parasite distribution clearly showed that Varroa mites were present in all regions. However, the degree of mite density varies not only between apiaries but also between colonies in the same apiary, while the bee louse, Barulla coeca, was detected in 23.1% and 5.8% of apiaries in the western region and southern region of Libya, respectively. On the other hand, all the inspected apiaries in the northern region were not infested. Conclusion: Lack of knowledge about honey bee parasites, poor management practices, and the lack of proper distance between hives of migrated apiaries have been attributed as the possible reason for the spread of these two parasites, especially the Varroa mites in the country.

Conditional discrimination and response chains by worker bumblebees (Bombus impatiens Cresson, Hymenoptera: Apidae).

We trained worker bumblebees to discriminate arrays of artificial nectaries (one, two, and three microcentrifuge tubes inserted into artificial flowers) from which they could forage in association with their location in a three-compartmental maze. Additionally, we challenged bees to learn to accomplish three different tasks in a fixed sequence during foraging. To enter the main three-compartmented foraging arena, they had first to slide open doors in an entry box to be able to proceed to an artificial flower patch in the main arena where they had to lift covers to the artificial nectaries from which they then fed. Then, the bees had to return to the entrance way to their hive, but to actually enter, were challenged to rotate a vertically oriented disc to expose the entry hole. The bees were adept at associating the array of nectaries with their position in the compartmental maze (one nectary in compartment one, two in two, and three in three), taking about six trials to arrive at almost error-free foraging. Over all it took the bees three days of shaping to become more or less error free at the multi-step suite of sequential task performances. Thus, they had learned where they were in the chain sequence, which array and in which compartment was rewarding, how to get to the rewarding array in the appropriate compartment, and finally how to return as directly as possible to their hive entrance, open the entrance, and re-enter the hive. Our experiments were not designed to determine the specific nature of the cues the bees used, but our results strongly suggest that the tested bees developed a sense of subgoals that needed to be achieved by recognizing the array of elements in a pattern and possibly chain learning in order to achieve the ultimate goal of successfully foraging and returning to their colony. Our results also indicate that the bees had organized their learning by a hierarchy as evidenced by their proceeding to completion of the ultimate goal without reversing their foraging paths so as to return to the colony without food.

Problem solving by worker bumblebees Bombus impatiens (Hymenoptera: Apoidea).

During foraging, worker bumblebees are challenged by simple to complex tasks. Our goal was to determine whether bumblebees could successfully accomplish tasks that are more complex than those they would naturally encounter. Once the initial training to successfully manipulate a simple, artificial flower was completed, the bees were either challenged with a series of increasingly difficult tasks or with the most difficult task without the opportunity for prior learning. The first experiment demonstrated that the bees learned to slide or lift caps that prevented their access to the reinforcer sugar solution through a series of tasks with increasing complexity: moving one cap either to the right or to the left, or lifting it up. The second experiment demonstrated that the bees learned to push balls of escalating masses (diameters 1 and 1.27 cm) from the access to the hidden rewarding (sugar syrup) reservoir of artificial flowers. In both experiments, when bees with experience with only the simplest task (i.e. an artificial flower without a barrier to the reinforcer) were presented next with the most complex or difficult task, they failed. Only by proceeding through the series of increasingly difficult tasks were they able to succeed at the most difficult. We also noted idiosyncratic behaviours by individual bees in learning to succeed. Our results can be interpreted within the context of Skinnerian shaping and possibly scaffold learning.