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Osmia cornuta (Hymenoptera Megachilidae) densities required for apple pollination: a cage study
publication date: Oct 1, 2004
| Journal Name | Vol. 43 (3) pp. 118 - 122 | | DOI | -- | | Date | October 2004 | | | | Article Title | Osmia cornuta (Hymenoptera Megachilidae) densities required for apple pollination: a cage study | | Author(s) | Edith Ladurner, Luca Recla, Manfred Wolf, Roland Zelger and Giovanni Burgio | | Abstract | To estimate Osmia cornuta densities required for pollination of ‘Braeburn’ apple, trees were caged and supplied with different bee densities in 2000 and 2001. The following pollination treatments were compared: (1) One O. cornuta pair per five trees: 5 adjacent trees, 2 ‘Braeburn’, 1 ‘Granny Smith’ (pollenizer) and 2 ‘Braeburn’, caged with 1 female and 1 male O. cornuta; (2) One O. cornuta pair per tree: 5 trees as above, caged with 5 female and 5 male O. cornuta; (3) Open pollination: 5 trees as above, uncaged; (4) No pollinators: 5 trees as above, caged without pollinating insects. Fruitlet-set (fruitlets retained on the tree before June drop), misshapen fruit-percentages (percent fruits with at least one empty carpel), and seed-set (number of seeds per fruit) were measured. Cages with no pollinators had the lowest fruitlet-set (2000: 11.5%; 2001: 7.7%) and seed-set (2000: 1.6; 2001: 1.9), and the highest proportion of misshapen fruits (2000: 96.8%; 2001: 96.3%) in both years. Values obtained in cages with one O. cornuta pair per five trees were not significantly different from those obtained in open-pollinated trees. Cages with one O. cornuta pair per tree had fruitlet-set (2000: 37.9%; 2001: 20.4%) similar to cages with one pair per five trees (2000: 33.0%; 2001: 18.6%) or to open-pollinated trees (2000: 31.0%; 2001: 21.7%), but had significantly higher seed-set (2000: 7.5 vs. 5.7 and 6.0, respectively; 2001: 5.6 vs. 4.3 and 4.0, respectively) and lower misshapen fruit incidence (2000: 27.5% vs. 54.0% and 56.5%, respectively; 2001: 54.8% vs. 71.5% and 76.1%, respectively) in both years. One O. cornuta pair per five trees can provide commercially acceptable fruitlet-set, whereas one O. cornuta pair per tree can ensure maximum seed-set and thus high-quality yields on ‘Braeburn.’ | | Keywords | Osmia cornuta, pollinator density, apple pollination, fruitlet-set, seed-set | | Download |   |
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