Diversitet og tetthet av pollinerende insekter i et jordbærfelt på øya Sekken i Storfjorden, sør om Molde.

Summary

Insects may have a great impact on strawberry yields and in many other plants. In a time of climate change and where the number of insects seems to decrease, questions have been asked about how the populations of pollinating insect species are doing. Therefore, in this project we would map the status of these beneficial insects in a strawberry field on the island of Sekken, south of Molde, in the period 2.-15. June 2020. In the experimental field, a square of 25m x 50m was marked. In the experimental square, a total of 12 so-called "pan-traps" were set out to catch insects at four different points. These traps consisted of plastic cups spray-painted either white, blue or yellow, and mounted on piles. The cups were half-filled with mild soapy water. The traps were inspected three times a day throughout the whole trial period. In this square, four observation points were also pointed. At each observation point, a square of 1m x 1m with approx. 100 strawberry flowers were marked. In sequences of 15 min., the frequency and type of insect that came and visited the flowers were recorded. 20 such observations were made at each observation point during the entire experimental period. In the insect traps, 189 different insects were caught. Of these, there were 172 diptera, i.e. flies and mosquitoes. 11 wasps were also caught, which included 7 wild bees. No bumblebees were caught. The catch was very weather dependent with no catches as it was low temperature (<10 ° C) and rain. During the observations 47 hoverflies, 25 wild bees, 7 bumblebees and 5 other flies were observed, altogether 84 insects. These made 139 flower visits. On average, the wild bees visited more flowers than the hoverflies and spend more time on each flower, thus it seems in this strawberry field that the wild bees were most important for the pollination of the flowers.