Genetic Characterization of Exotic Commercial Honey Bee (Hymenoptera: Apidae) Populations in Thailand Reveals High Genetic Diversity and Low Population Substructure

Domestication of animal species is often associated with a reduction in genetic diversity. The honey bee, Apis mellifera Linnaeus, 1758, has been managed by beekeepers for millennia for both honey and wax production and for crop pollination. Here we use both microsatellite markers and sequence data from the mitochondrial COI gene to evaluate genetic variation of managed A. mellifera in Thailand, where the species is introduced. Microsatellite analysis revealed high average genetic diversity with expected heterozygosities ranging from 0.620 ± 0.184 to 0.734 ± 0.071 per locus per province. Observed heterozygosities were generally lower than those expected under Hardy-Weinberg equilibrium, both locally and across the population as a whole. Mitochondrial sequencing revealed that the frequency of two evolutionary linages (C-Eastern European and O-Middle Eastern) are similar to those observed in a previous survey 10 yr ago. Our results suggest that Thai beekeepers are managing their A. mellifera in ways that retain overall genetic diversity, but reduce genetic diversity between apiaries.

Genetic Differentiation of the Giant Honey Bee (Apis dorsata) in Thailand Analyzed by Mitochondrial Genes and Microsatellites

Genetic diversity and population differentiation of the giant honey bee (Apis dorsata) in Thailand were examined. Six PCR-RFLP mitotypes were generated from digestion of the COI-COII, Cytb-tRNA(ser), ATPase6-8, and lrRNA genes with Dra I and Hin fI. Low genetic diversity (h=0.074, pi=0.032%) and a lack of genetic population differentiation between A. dorsata originating from geographically different regions were observed from mtDNA polymorphisms (P > 0.05). In contrast, microsatellite (A14, A24, and A88) polymorphisms revealed a relatively high level of genetic diversity in A. dorsata (H (o)=0.68-0.74, average number of alleles per locus=6.0-9.0). Both A24 and A88 indicated significant population differentiation between bees from the north-to-central region (north, northeast, and central regions), peninsular Thailand, and Samui Island.

Social parasitism by workers in queenless and queenright Apis cerana colonies

We examined worker reproduction in queenless and queenright Apis cerana colonies to determine if they are parasitized by workers from other nests. The results demonstrate that 2-6% of workers in queenright colonies are from another nest (non-natal), but these workers are not statistically more likely to have activated ovaries than natal workers, and are therefore unlikely to be active parasites. However, in queenless colonies we found a significant difference between the proportion of non-natal (72.7%) and natal (36.3%) workers with activated ovaries. Non-natal workers also had significantly higher reproductive success than natal workers: 1.8% of workers were non-natal, but these laid 5.2% of the eggs and produced 5.5% of the pupae. Unlike A. florea, the proportion of non-natal workers does not increase in queenless nests.

Purification and characterization of alpha-glucosidase I from Japanese honeybee (Apis cerana japonica) and molecular cloning of its cDNA

alpha-Glucosidase (JHGase I) was purified from a Japanese subspecies of eastern honeybee (Apis cerana japonica) as an electrophoretically homogeneous protein. Enzyme activity of the crude extract was mainly separated into two fractions (component I and II) by salting-out chromatography. JHGase I was isolated from component I by further purification procedure using CM-Toyopearl 650M and Sephacryl S-100. JHGase I was a monomeric glycoprotein (containing 15% carbohydrate), of which the molecular weight was 82,000. Enzyme displayed the highest activity at pH 5.0, and was stable up to 40 degrees C and in a pH-range of 4.5-10.5. JHGase I showed unusual kinetic features: the negative cooperative behavior on the intrinsic reaction on cleavage of sucrose, maltose, and p-nitrophenyl alpha-glucoside, and the positive cooperative behavior on turanose. We isolated cDNA (1,930 bp) of JHGase I, of which the deduced amino-acid sequence (577 residues) confirmed that JHGase I was a member of alpha-amylase family enzymes. Western honeybees (Apis mellifera) had three alpha-glucosidase isoenzymes (WHGase I, II, and III), in which JHGase I was considered to correspond to WHGase I.

Asian honeybees parasitize the future dead

The queen of a honeybee colony has a reproductive monopoly because her workers' ovaries are normally inactive and any eggs that they do lay are eaten by their fellow workers. But if a colony becomes queenless, the workers start to lay eggs, stop policing and rear a last batch of males before the colony finally dies out. Here we show that workers of the Asian dwarf red honeybee Apis florea from other colonies exploit this interval as an opportunity to move in and lay their own eggs while no policing is in force. Such parasitism of queenless colonies does not occur in the western honeybee A. mellifera and may be facilitated by the accessibility of A. florea nests, which are built out in the open.

Isolation and characterization of major royal jelly cDNAs and proteins of the honey bee (Apis cerana)

An expressed sequence tag (EST) library was established from the hypopharyngeal glands of Apis cerana. Sixty-six recombinant clones, possessing inserts > 500 bp, were randomly selected and unidirectional sequenced. Forty-two of these (63.6%) were identified as homologues of Major Royal Jelly Proteins families 1, 2, 3, and 4 of A. mellifera (AmMRJP) for which MRJP1 was the most abundant family. The open-reading frame of the MRJP1 homologue (AcMRJP1) was 1299 nucleotides that encoded 433 deduced amino acids with three predicted N-linked glycosylation sites. The AcMRJP1 sequence showed 93% and 90% homologies with nucleotide and deduced amino acid sequences of AmMRJP1, respectively. Two complete transcripts of apisimin, and one and two partial transcripts of alpha-glucosidase and glucose oxidase, were also isolated. In addition, the royal jelly proteins of A. cerana were purified and characterized using Q-Sepharose and Sephadex G-200 column chromatography. The native forms of protein peaks A1, A2, B1, and C1 were 115, 55, 50, and 300 kDa, respectively. SDS-PAGE analysis indicated that A1 and C1 were dimeric and oligomeric forms of the 80 kDa and 50 kDa subunits, respectively. The ratio of the total protein quantities of A1 : A2 : B1 : C1 were 2.52 : 4.72 : 1 : 12.21. Further characterization of each protein, using N-terminal and internal peptide sequencing, revealed that the respective proteins were homologues of MRJP3, MRJP2, MRJP1, and MRJP1 of A. mellifera.