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Bumblebee pollination of summer crops
27 June 2010
This year we see a great increase in the use of bumblebees for pollination of various ‘summer crops’ such as open field tomato, watermelon, (hybrid) sunflower, sweet pepper, rose-hip, etc., all around the world. Crops in which bumblebee pollination can significantly contribute to increased yields (bigger fruits, more fruits, more seeds) but also for example early ripening in melons.
During summer, when daily temperatures can easily reach up to 30 °C/ 86 °F or higher, it is very important to protect the Tripols against excessive sun radiation. Bumblebees keep their nest temperature between 28 - 33 °C/82.4 - 91.4 °F. For this purpose they either ventilate in case of warmer temperatures or incubate the brood in case of colder temperatures. The best pollination activity is achieved when the majority of the bumblebees are not involved in regulating the internal climate, but free to pollinate. Without sun protection and in hot summer conditions, the temperature inside the bumblebee hives might easily run up to 40 °C/104 °F or even higher. These conditions will often result in damage to the bumblebee colonies affecting the pollination activity.
Therefore we advise to provide as much shade as possible. Cover the Tripols preferably with a white polystyrene sheet which is larger than the top surface of the Tripol (e.g. 20cm at both sides), to protect against side radiation as well. Keep some ventilation space between the Tripols and the cover. Some heavy objects, e.g. stones or sand, should be put on top of the sheet to prevent it from being blown away by wind. Make sure the polystyrene sheet does not touch the sliding doors, accidently closing the hives. In very extreme conditions it might also be advisable to bury the Tripols in the soil to protect them against severe heat. Use textured tubes to connect the entrances/exits of the Tripols with the outdoor.
For more details, please contact: Natupol@koppert.nl