Effect of various supplements on productive performance of honey bees, in the south Wollo Zone, Ethiopia.

The productivity and well-being of honey bee colonies are greatly influenced by the nutrients present in the hives. A study was conducted to evaluate different supplemental feeds on honey bee productive performance during dearth periods. Thirty colonies were grouped into five (four treatment groups and one control group) and each group contained three sub-groups (2 weak, 2 strong, and 2 very strong). Control groups were not given any supplementation. Treatment diets were T1 (50% sugar syrup + 14% roasted barley powder (beso) + 36% roasted spiced pea powder (Shiro)), T2 (50% powder sugar + 14% white sorghum powder + 36% bakery yeast, T3 (50% powder sugar + 14% white sorghum powder + 36% skimmed milk powder), T4 (50% sugar syrup with infusion of stinging nettle and 1% kerefa + 50% white sorghum powder). Feed was given on the entrance sides. The performance of experimental colonies was measured every 21 days in two phases during the dry season (from 3_2_2021 to 27_4_2021) and the rainy season (from 28-7_2021 to 1_10_2021). Feed intake, space (cm2) of pollen, nectar, and honey in the comb were measured using a frame-sized transparent grid meter. The study revealed significant differences (p<0.0001) in all measured parameters among the various treatments. The diet provided by T4 showed the highest levels of crude protein (18.15%) and carbohydrates (92.15%), whereas the diet presented by T3 had the lowest crude protein content (6.66%) and the diet offered by T1 had the lowest carbohydrate content (61.91%). In general, colonies that received T4 showcased superior performance compared to others. They exhibited a feed intake of 98.3%, a nectar area of 54.3 cm2, a pollen area of 68.7 cm2, a honey area of 311.2 cm2, and a honey yield of 7 kg. Consequently, their net profit amounted to 51.54 USD. On the other hand, the colonies that received T1 had the lowest performance indicators. They demonstrated a feed intake of only 54.7%, a nectar area of 37.6 cm2, a pollen area of 48.8 cm2, a honey area of 254.3 cm2, a honey yield of 2.8 kg, and a net profit of 18.81 USD. The significance of this study was to enable the beekeepers in realizing the effects of feed supplements on the productivity and profitability of honeybee colonies.

Expression of Molecular Markers of Resilience against Varroa destructor and Bee Viruses in Ethiopian Honey Bees (Apis mellifera simensis) Focussing on Olfactory Sensing and the RNA Interference Machinery.

Varroa destructor mites and the viruses it vectors are two major factors leading to high losses of honey bees (Apis mellifera) colonies worldwide. However, honey bees in some African countries show resilience to varroa infestation and/or virus infections, although little is known about the mechanisms underlying this resilience. In this study, we investigated the expression profiles of some key molecular markers involved in olfactory sensing and RNA interference, as these processes may contribute to the bees' resilience to varroa infestation and virus infection, respectively. We found significantly higher gene expression of the odorant binding protein, OBP14, in the antennae of Ethiopian bees compared to Belgian bees. This result suggests the potential of OBP14 as a molecular marker of resilience to mite infestation. Scanning electron microscopy showed no significant differences in the antennal sensilla occurrence and distribution, suggesting that resilience arises from molecular processes rather than morphological adaptations. In addition, seven RNAi genes were upregulated in the Ethiopian honey bees and three of them-Dicer-Drosha, Argonaute 2, and TRBP2-were positively correlated with the viral load. We can conclude that the antiviral immune response was triggered when bees were experiencing severe viral infection and that this might contribute to the bees' resilience to viruses.

Metagenomic Approach with the NetoVIR Enrichment Protocol Reveals Virus Diversity within Ethiopian Honey Bees (Apis mellifera simensis).

Metagenomics studies have accelerated the discovery of novel or divergent viruses of the honey bee. However, most of these studies predominantly focused on RNA viruses, and many suffer from the relatively low abundance of viral nucleic acids in the samples (i.e., compared to that of the host). Here, we explored the virome of the Ethiopian honey bee, Apis mellifera simensis, using an unbiased metagenomic approach in which the next-generation sequencing step was preceded by an enrichment protocol for viral particles. Our study revealed five well-known bee viruses and 25 atypical virus species, most of which have never been found in A. mellifera before. The viruses belong to Iflaviridae, Dicistroviridae, Secoviridae, Partitiviridae, Parvoviridae, Potyviridae, and taxonomically unclassified families. Fifteen of these atypical viruses were most likely plant-specific, and the remaining ten were presumed to be insect-specific. Apis mellifera filamentous virus (AmFV) was found in one sampling site out of 10. Two samples contained high read counts of a virus similar to Diatraea saccharales densovirus (DsDNV), which is a virus that causes high mortality in the sugarcane borer. AmFV and the DsDNV-like virus were the only DNA viruses found. Three viruses that primarily infect Drosophila spp. were also discovered: La Jolla virus (LJV), Kilifi virus (KiV), and Thika virus. Our study suggests that phoretic varroa mites are involved in the transmission of LJV and KiV and that both viruses replicate in mites and adult bees. We also found an overwhelming dominance of the deformed wing virus type B variant, which fits well with the apparently harmless infestation by Varroa destructor. It was suggested that Ethiopian bees have developed tolerance against virus infections as the result of natural selection.

Factors restraining the population growth of Varroa destructor in Ethiopian honey bees (Apis mellifera simensis).

Worldwide, the ecto-parasitic mite Varroa destructor has been assigned as an important driver of honey bee (Apis mellifera) colony losses. Unlike the subspecies of European origin, the honey bees in some African countries such as Uganda and Ethiopia may not be as threatened or suffer less from mite-infestations. However, only little is known about the factors or traits that enable them to co-exist with the mite without beekeepers' intervention. Hence, this study was designed to investigate these factors or traits that limit the Varroa mite population in Ethiopian honey bees (Apis mellifera simensis). The study was conducted in the primary honey producing region of Ethiopia, i.e. Tigray. Mite infestation levels were shown to be lower in traditional hives (when compared to framed hives) and when colonies were started up from swarm catching (when compared to colony splitting). However, the influence of the comb cell size on mite infestation was not observed. With respect to the bee biology, the hygienic behavior was shown to be high (pin-test: 92.2% removal in 24 hours) and was negatively correlated with phoretic mite counts (Pearson; r = -0.79; P < 0.01) and mite infestation levels in brood (Pearson; r = -0.46; P < 0.001). Efforts to estimate the Varroa mite reproductive capacity were seriously hampered by an extremely low brood infestation level. From the 133 founder mites found (in 6727 capped brood cells) only 18.80% were capable of producing a reproductive progeny. Failure to produce adult male progeny was unexpectedly high (79.70%). We have suggested a few adaptations to the test protocols allowing to estimate the protective traits of honey bee colonies under very low Varroa pressure. Apart from that, this study demonstrates that the honey bees from Ethiopia are suitable targets to further decipher the genetic predisposition of resistance against V. destructor. It is still unclear to what extent simensis differs from the more common scutellata subspecies.