Grant awarded by National Science Center: Miniatura 2019–2020: 2019/03/X/NZ8/01461

Grant holder

Aleksandra Łangowska

 

Pollination services, primarily provided by insects, are a key function of ecosystems, but also a necessary input to the production of many agricultural crops around the world. Currently, there is great interest in pollinating insects due to the observed general decline in their numbers and diversity on a global scale, and among insect pollinators special attention is paid to bees. In contrast, pollinators other than bees have so far received little attention, although they have been shown to contribute significantly to world food production.
The least known group of pollinators seems to be nocturnal animals. Meanwhile, night moths have been shown to visit many more plants than previously thought, including many crops. Moths carry large amounts of pollen on their bodies, and they transport it longer distances than bees, so they seem to complement the activity of daytime insects.
Among the plants visited by moths is oilseed rape, a plant of significant economic importance and a large area of cultivation. Rapeseed pollination occurs partly as a result of autogamy, but mainly with the participation of vectors: wind and insects. The presence of pollinating insects affects not only the size but also the quality of the rapeseed yield. The list of taxa of daytime visitors in oilseed rape is largely known and their importance for pollination varies. On the other hand, almost nothing is known about insects visiting rape flowers at night. The aim of the project was to determine the significance of night-active insects for oilseed rape yield in a pilot field experiment.
To determine the contribution of pollinators to the rapeseed yield, fragments of flowering crops were isolated by placing mesh cages on them. The mesh allowed pollen to be carried by the wind but kept insects from getting inside. On some of the cages, the net was installed only during the day and removed at night, so that only nocturnal insects had access to flowers, and on some cages, the other way around: the net was put on at night and removed during the day. Some cages isolated the plants throughout the flowering period, so pollinators did not visit the flowers at all. At harvest time, several yield parameters were determined for plants previously available for different pollinators. The experiment confirmed the importance of pollinators active during the day for one of the most important yield parameters – seed weight, measured as weight of 1000 seeds. The weight of seeds in plants visited by daytime insects was higher by 6% than in plants pollinated only by wind. This value is within the lower limits of the range indicated by other research. At the same time, the seed weight in the year of the experiment was very low due to unfavorable weather conditions, mainly the drought lasting throughout the growing season. In addition, during the flowering period temperatures were very low, with frosts. Therefore, although the experiment showed the importance of insects active during the day, but generally did not show the significance of insects active at night, the importance of the latter for oilseed rape yielding cannot be excluded. Low temperatures at night in May 2020 completely prevented insect activity – the crops were simply not visited by insects at all at night.
Rapeseed was chosen as a model plant for the pilot because of its economic importance. During the flowering of oilseed rape, nighttime temperatures vary between years, and within a very wide range. Therefore, it seems advisable to include other crop species that bloom later in the season in future research. Knowledge of the pollinating fauna can help in targeting and promoting conservation activities in agrocenoses, e.g., through the selection of plant protection products.