Key Points of Bee Pollination Technology in Strawberry Cultivation
Greenhouse strawberry cultivation takes place in winter and early spring, when temperatures are low, humidity is low, daylight is short, and insects are few. This affects anther dehiscence and pollen dispersal, leading to poor pollination and the easy development of various deformed fruits, seriously affecting yield and quality. To create good pollination conditions, besides paying attention to ventilation and reducing air humidity, the main measure is to use bees for supplementary pollination. Research shows that in greenhouses where bees are used for pollination, the fruit-setting rate of strawberries is significantly increased, fruit yield rises by 30-50%, and the number of deformed fruits is only 20% of that in areas without bees.
5-10 days before ventilation, thoroughly control pests and diseases once in the greenhouse, especially insect pests. After the beehives are placed inside, pesticides generally cannot be applied again, and insecticides are especially prohibited. One week before strawberry flowering, move the beehives into the greenhouse. Generally, one hive is placed per greenhouse, with one bee per strawberry plant. Place the beehive in the middle of the greenhouse in a well-lit spot, 15 cm above the ground. The hive entrance should avoid direct light, so that bees flying out do not hit the greenhouse film while facing the light, which would increase mortality. Placement is best done in the morning or at dusk. Bees leave the hive to activity at temperatures of 5-35°C, and their optimum living temperature is 15-25°C. The temperature range for bee activity is consistent with the optimum temperature for strawberry anther dehiscence (13-20°C). When the temperature remains below 10°C for a long time, bees reduce or stop leaving the hive. To create a good environment for bee pollination, the temperature must not be too low. However, when the temperature exceeds 30°C, ventilation should be carried out promptly.
In production, the living habits of bees should be understood to minimize deaths. In actual operation, the following points should be noted:
1. Reduce the humidity inside the greenhouse. Especially after long periods of rainy weather, humidity inside the greenhouse is high and many water droplets gather on the greenhouse film. When bees go out to activity on clear days, flying is difficult and they are easily knocked down by water and die. Therefore, when cloudy weather suddenly turns clear, increase ventilation to remove moisture. Desiccants such as lime bottles can be placed inside the hive to reduce humidity.
2. When multiple layers of cover are used in the greenhouse, the medium and small greenhouse films should be rolled down to the bottom on both sides when removed, not half removed and half left in place. Otherwise, bees flying around may get into the gaps between films and be pinched to death.
3. For pest and disease control, choose pesticides that are non-toxic or low-toxicity to bees. When spraying or using fumigants, close the hive entrance tightly, or move the hive outdoors and move it back into the greenhouse after 3-4 days to prevent bees from being poisoned to death.
4. In winter and early spring, nectar sources are scarce, so feeding must be strengthened. The feeding amount should be based on whether the bees can carry out normal pollination after feeding. Otherwise, excessive feed may cause bees not to pollinate, or too little feed may leave bees too weak to fly and pollinate, resulting in pollination failure. Choose white granulated sugar and clean water at a 1:1 ratio, boil, cool, and feed. The water content must not be too high, to prevent bees from getting sick. Each hive board of bees (2500 bees) uses 1 kg of white granulated sugar, to be fed before January. Alternatively, boil white granulated sugar and clean water at a 2:1 ratio into a paste, fill the bee trough, and feed all at once while increasing the amount of pollen feed.
5. When releasing bees, to prevent the colony from escaping through the ventilation opening, add an escape-proof net at the ventilation opening.
6. The bee release period is from the flowering of the first terminal inflorescence of strawberry to March of the following year.