Ayman A. Owayss

Population genomics of the honey bee reveals strong signatures of positive selection on worker traits

Significance Most hypotheses explaining the evolution of sociality in insects assume that positive selection drives the evolution of worker traits. Yet we know little about the extent of natural selection acting on social insects. We produced a map of positive selection for the honey bee through analysis of 40 individual genomes. We found strong evidence of positive selection acting on genes and regulatory sequences, and we discovered that mutations in worker-biased proteins tend to have greater fitness effects than mutations in queen-biased proteins. We also found many instances of positive selection acting on genes that influence worker traits, suggesting that worker phenotypes represent a major vector for adaptation in social insects. Most theories used to explain the evolution of eusociality rest upon two key assumptions: mutations affecting the phenotype of sterile workers evolve by positive selection if the resulting traits benefit fertile kin, and that worker traits provide the primary mechanism allowing social insects to adapt to their environment. Despite the common view that positive selection drives phenotypic evolution of workers, we know very little about the prevalence of positive selection acting on the genomes of eusocial insects. We mapped the footprints of positive selection in Apis mellifera through analysis of 40 individual genomes, allowing us to identify thousands of genes and regulatory sequences with signatures of adaptive evolution over multiple timescales. We found Apoidea- and Apis-specific genes to be enriched for signatures of positive selection, indicating that novel genes play a disproportionately large role in adaptive evolution of eusocial insects. Worker-biased proteins have higher signatures of adaptive evolution relative to queen-biased proteins, supporting the view that worker traits are key to adaptation. We also found genes regulating worker division of labor to be enriched for signs of positive selection. Finally, genes associated with worker behavior based on analysis of brain gene expression were highly enriched for adaptive protein and cis-regulatory evolution. Our study highlights the significant contribution of worker phenotypes to adaptive evolution in social insects, and provides a wealth of knowledge on the loci that influence fitness in honey bees.

The indigenous honey bees of Saudi Arabia (Hymenoptera, Apidae, Apis mellifera jemenitica Ruttner): Their natural history and role in beekeeping

Abstract Apis mellifera jemenitica Ruttner (= yemenitica auctorum: vide Engel 1999) has been used in apiculture throughout the Arabian Peninsula since at least 2000 BC. Existing literature demonstrates that these populations are well adapted for the harsh extremes of the region. Populations of Apis mellifera jemenitica native to Saudi Arabia are far more heat tolerant than the standard races often imported from Europe. Central Saudi Arabia has the highest summer temperatures for the Arabian Peninsula, and it is in this region where only Apis mellifera jemenitica survives, while other subspecies fail to persist. The indigenous race of Saudi Arabia differs from other subspecies in the region in some morphological, biological, and behavioral characteristics. Further taxonomic investigation, as well as molecular studies, is needed in order to confirm whether the Saudi indigenous bee populations represent a race distinct from Apis mellifera jemenitica, or merely an ecotype of this subspecies.

The large carpenter bees of central Saudi Arabia, with notes on the biology of Xylocopa sulcatipes Maa (Hymenoptera, Apidae, Xylocopinae)

Abstract The large carpenter bees (Xylocopinae, Xylocopa Latreille) occurring in central Saudi Arabia are reviewed. Two species are recognized in the fauna, Xylocopa (Koptortosoma) aestuans (Linnaeus) and Xylocopa (Ctenoxylocopa) sulcatipes Maa. Diagnoses for and keys to the species of these prominent components of the central Saudi Arabian bee fauna are provided to aid their identification by pollination researchers active in the region. Females and males of both species are figured and biological notes provided for Xylocopa sulcatipes. Notes on the nesting biology and ecology of Xylocopa sulcatipes are appended. As in studies for this species from elsewhere, nests were found in dried stems of Calotropis procera (Aiton) (Asclepiadaceae) and Phoenix dactylifera L. (Arecaceae).

Nectar secretion dynamics and honey production potentials of some major honey plants in Saudi Arabia

The contribution of a bee plant species to honey production depends on the plant’s nectar secretion quality and quantity, which is mainly governed by biotic and abiotic factors. The aim of the current study, was to investigate the nectar secretion dynamics and honey production potential of 14 major bee plant species of the target area. We examined the quantity and dynamics of nectar sugar per flower five times a day using a nectar sugar washing technique and direct measuring of nectar with calibrated capillary tubes. The average nectar sugar amount of the species varied from 0.41 mg/flower to 7.7 mg/flower (P < 0.0001). The honey sugar per flower was used to extrapolate the honey production potential per plant and per hectare of land. Accordingly the honey production potential of the species observed to vary from 14 kg/hectare in Otostegia fruticosa to 829 kg/hectare in Ziziphus spina-christi. The nectar secretion dynamics of the species generally showed an increasing trend early in the morning, peaking toward midday, followed by a decline but different species observed to have different peak nectar secretion times. Generally, the tree species secreted more nectar sugar/flower than the herbs. The nectar secretion amount of the species was positively correlated with the ambient temperature, indicating the adaptation of the species to hot climatic conditions. However, different species were observed to have a different optimum temperature for peak nectar secretion. Despite the limited rainfall and high temperature of the area, many plants were found to have good potential for honey production. The monetary value of honey per hectare of the studied honeybee plant species can be of equal or greater than the per-hectare monetary value of some cultivated crops that require numerous inputs. In addition, the information generated is believed to be useful in apiary site selection and to estimate the honey bee colony carrying capacity of an area.

Performance evaluation of indigenous and exotic honey bee (Apis mellifera L.) races in Assir region, southwestern Saudi Arabia

This study was conducted in the Assir region of southwestern Saudi Arabia to compare the activities of honeybee colonies of indigenous Apis mellifera jemenitica (AMJ) and imported Apis mellifera carnica (AMC) during the late summer and autumn of 2009 and 2010. The results showed that the workers of the two races exhibited relatively similar forage timings throughout the period of study (August-November). The highest numbers of foraged workers were recorded at 6:00xa0am, 10:00xa0am and 6:00xa0pm, while the lowest numbers were recorded at 8:00xa0am, 12:00xa0pm and 4:00xa0pm. Although foraging activity was negatively affected by decreased temperature, AMJ was more resistant to cold than AMC. In the first season, the smallest amount of worker brood rearing was recorded in August, and the highest amount of rearing occurred in November in both races. In the second season, the smallest amount of brood was observed in October, and the largest amount of brood was observed in November. Brood rearing and pollen collecting was significantly (Pxa0<xa00.05) higher in AMJ compared with AMC, while AMC stored significantly (Pxa0<xa00.05) more honey than AMJ during the tested periods. In AMJ colonies, a positive significant correlation was observed between the area of the sealed worker brood and stored pollen, while a negative but nonsignificant correlation was observed between the area of the sealed worker brood and surplus honey. In the AMC colonies, a positive significant correlation was observed between the area of the sealed brood and the stored pollen and surplus honey.

Egyptian honeybee pollen as antimicrobial, antioxidant agents, and dietary food supplements

In this study, three Egyptian bee pollen types from different plant sources, namely maize (Zea mays), clover (Trifolium alexandrinum), and date palm (Phoenix dactylifera), were evaluated as natural antimicrobial agents, antioxidants, and food additives. A methanolic extract of maize bee pollen exhibited the highest antibacterial activity, followed by clover and date palm bee pollen. Staphylococcus aureus and Escherichia coli were the most sensitive, followed by Listeria monocytogenes, Salmonella enteritidis, and Pseudomonas aeruginosa. In ghee, all methanolic extracts, especially that of maize bee pollen, showed high antioxidant activities as radical scavenger substances and as inhibitors of lipid peroxidation. Sensory evaluation of yoghurt supplemented with different bee pollens revealed that maize bee pollen improve texture, increased gel strength, and decreased syneresis and had favorable nutty flavor, while clover and date palm pollen added a sweet taste and bean-like flavor, respectively. These findings establish the potential of Egyptian maize and clover bee pollen as antioxidants, antimicrobial agents, promising natural food supplements, and natural preservatives.

Pollination ecology of Acacia gerrardii Benth. (Fabaceae: Mimosoideae) under extremely hot-dry conditions

Talh trees (Acacia gerrardii Benth.) are acacias that are native to the arid and semiarid Africa and west Asia. We investigated the flowering biology, pod set and flower visitors of Talh and discussed the role of these visitors in pollen transfer. The Talh trees blossomed laterally on the nodes of one-year-old twigs. Each node produced 21 flower buds seasonally. Each flower bud opened to a flower head (FH) of 60 florets. The bagged FHs podded significantly (p ⩽ 0.05) less than did the unbagged FHs. The FHs were visited by 31 insect species (25 genera, 16 families and 5 orders). The major taxa were honeybees, megachilids, butterflies, ants, beetles and thrips. Each of honeybees, megachilids and beetles showed a significant (p ⩽ 0.05) hourly pattern, while each of butterflies, ants and thrips had no hourly pattern (p > 0.05). Furthermore, some birds and mammals touched the Talh FHs. Talh trees evolved a mass flowering behavior to face pre- and post-flowering obstacles. Megachilids seemed to play the major effort of zoophily because of their relatively high numbers of individuals and species and their effective movement behavior on the FH surface. Nevertheless, honeybees and other insects and vertebrate taxa also contributed to the pollen transfer. These results greatly contribute to our understanding of the pollination ecology of acacias, especially Arabian acacias.

Organic Tracers from Asphalt in Propolis Produced by Urban Honey Bees, Apis mellifera Linn.

Propolis is a gummy material produced by honey bees to protect their hives and currently has drawn the attention of researchers due to its broad clinical use. It has been reported, based only on observations, that honey bees also collect other non-vegetation substances such as paint or asphalt/tar to make propolis. Therefore, propolis samples were collected from bee hives in Riyadh and Al-Bahah, a natural area, Saudi Arabia to determine their compositional characteristics and possible sources of the neutral organic compounds. The samples were extracted with hexane and analyzed by gas chromatography-mass spectrometry. The results showed that the major compounds were n-alkanes, n-alkenes, methyl n-alkanoates, long chain wax esters, triterpenoids and hopanes. The n-alkanes (ranging from C17 to C40) were significant with relative concentrations varying from 23.8 to 56.8% (mean = 44.9+9.4%) of the total extracts. Their odd carbon preference index (CPI) ranged from 3.6 to 7.7, with a maximum concentration at heptacosane indicating inputs from higher plant vegetation wax. The relative concentrations of the n-alkenes varied from 23.8 to 41.19% (mean = 35.6+5.1%), with CPI = 12.4-31.4, range from C25 to C35 and maximum at tritriacontane. Methyl n-alkanoates, ranged from C12 to C26 as acids, with concentrations from 3.11 to 33.2% (mean = 9.6+9.5%). Long chain wax esters and triterpenoids were minor. The main triterpenoids were α- and β-amyrins, amyrones and amyryl acetates. The presence of hopanes in some total extracts (up to 12.5%) indicated that the bees also collected petroleum derivatives from vicinal asphalt and used that as an additional ingredient to make propolis. Therefore, caution should be taken when considering the chemical compositions of propolis as potential sources of natural products for biological and pharmacological applications. Moreover, beekeepers should be aware of the proper source of propolis in the flight range of their bee colonies.

Nesting biology of two species of the large carpenter bees Xylocopa pubescens and Xylocopa fenestrata (Hymenoptera: Apidae) in north-western Pakistan

Abstract The large carpenter bees are very promising pollinators for many agriculture crops. The nesting biology and some foraging activities of these large carpenter bees are documented from the north-western Pakistan, most extent of its natural distribution, as these species are potentially important pollinators of cucurbit crops and some agriculture crops in the region. Nests of the large carpenter bees, Xylocopa pubescens Spinola, 1838 and Xylocopa fenestrata Fabricius, 1798, around the Ismaila village, Swabi, Khyber Pakhtunkhwa Province, Pakistan, were observed and sampled from June to August 2012 and 2013. Nest details were recorded and foraging times on various floral species were documented, with bees preferentially nesting in dead wooden stems of Poplar (Populus deltoides) and Sesbania (Sesbania bispinosa). The dissection of nests was carried out and both nest architecture and nesting biology of the species were described. The importance of such studies on wild bees in Pakistan is important for the melittologists, as it will help in conservation of wild bees. The study is also useful in using large carpenter bees for pollination purpose.

Olfactory associative behavioral differences in three honey bee Apis mellifera L. races under the arid zone ecosystem of central Saudi Arabia

Apis mellifera jemenitica is the indigenous race of honey bees in the Arabian Peninsula and is tolerant to local drought conditions. Experiments were undertaken to determine the differences in associative learning and memory of honey bee workers living in the arid zone of Saudi Arabia, utilizing the proboscis extension response (PER). These experiments were conducted on the indigenous race (A. m. jemenitica) along with two introduced European races (A. m. carnica and A. m. ligustica). The data revealed that A. m. jemenitica is amenable to PER conditioning and may be used in conditioning experiments within the olfactory behavioral paradigm. The results also demonstrated that the three races learn and retain information with different capacities relative to each other during the experimental time periods. Native Arabian bees (A. m. jemenitica) exhibited significantly lower PER percentage during second and third conditioning trials when compared to exotic races. Apis mellifera jemenitica also exhibited reduced memory retention at 2u202fh and 24u202fh when compared to A. m. carnica and A. m. ligustica. Therefore, the native Arabian bees were relatively slow learners with reduced memory retention compared to the other two races that showed similar learning and memory retention. Three or five conditioning trials and monthly weather conditions (October and December) had no significant effects on learning and memory in A. m. jemenitica. These results emphasized a novel line of research to explore the mechanism and differences in associative learning as well as other forms of learning throughout the year among bee races in the harsh arid conditions of Saudi Arabia. This is the first study in Saudi Arabia to demonstrate inter-race differences regarding olfactory associative learning between native Arabian bees and two introduced European honey bee races.