Pollination efficacy of stingless bees, Tetragonula pagdeni Schwarz (Apidae: Meliponini), on greenhouse tomatoes (Solanum lycopersicum Linnaeus)

The stingless bee Tetragonula pagdeni is distributed over a vast Southeast Asian territory. This species is commonly used as a commercial insect pollinator. Pollination efficacy of T. pagdeni was investigated with tomato (Solanum lycopersicum L.) cultivated in greenhouse environments. In the first experiment, the number of fruit sets, number of seeds, fresh weight, and fruit height were quantified in the greenhouse with stingless bees, without stingless bees, and with pollination by mechanical vibration by hand. In the second experiment, the treatments were conducted with tomatoes of indeterminate growth in the greenhouse with and without stingless bees to prevent variation among the different tomato plants. The obtained results showed that a greenhouse with stingless bees presented 85 ± 4.24 fruits per 100 flowers, more than a greenhouse with mechanical vibration (79.5 ± 2.12 fruits per 100 flowers) or a greenhouse without stingless bees (15 ± 0.00 fruits per 100 flowers). In addition, fruit produced in a greenhouse with stingless bees showed greater fruit weight and number of seeds than fruit produced in a greenhouse without stingless bees or pollinated by mechanical vibration. According to the obtained results, we suggest that T. pagdeni could be beneficial as an insect pollinator of greenhouse tomatoes in tropical regions, where the use of honeybees and bumblebees would be more difficult.

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 Structure of the Aphis craccivora (Hemiptera: Aphididae) From Thailand Inferred From Mitochondrial COI Gene Sequence

The cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is one of the most destructive insect pests of legume plants worldwide. Although outbreaks of this pest occur annually in Thailand causing heavy damage, its genetic structure and demographic history are poorly understood. In order to determine genetic structure and genetic relationship of the geographic populations of this species, we examined sequences of mitochondrial cytochrome c oxidase subunit I (COI) gene of 51 individuals collected from 32 localities throughout Thailand. Within the sequences of these geographic populations, 32 polymorphic sites defined 17 haplotypes, ranging in sequence divergence from 0.2% (1 nucleotide) to 2.7% (16 nucleotides). A relatively high haplotype diversity but low nucleotide diversity was detected in the populations of A. craccivora, a finding that is typical for migratory species. Phylogenetic analysis revealed a weak phylogeographic structuring among the geographic populations and among the haplotypes, indicating their close relationship. Considering the distance between the sampling sites, the occurrence of identical haplotypes over wide areas is noteworthy. Moreover, the low genetic distance (FST ranging from -0.0460 to 0.3263) and high rate of per-generation female migration (Nm ranging from 1.0323 to 20.3333) suggested population exchange and gene flow between the A. craccivora populations in Thailand.