Flower visitors in legume-intercrops

Abstract

Data were assessed in 2021 on three experimental fields (white lupin intercropped with oats, Andean lupin intercropped with maize and common sainfoin intercropped with maize). In each field legumes were grown in pure and intercropped stands. In addition, different varieties of lupins were grown. Data on shading (LAI) were assessed in maize-intercropped plots on two occasions with a SunScan Canopy Analysis System (‘SS1’, Delta-T devices, Cambridge, UK). For each date, the average LAI was calculated out of eight different measurements per plot. Data on inflorescences were collected by counting the number of inflorescences in one central square meter of a plot after every observation. Data on visitation frequency and visit duration were obtained by flower-visitor observations in 1 m² per plot. Intercropped and pure stands of respective experiments were observed consecutively. For the number of visits all insect flower visitors to inflorescences of legumes within 6 min and 1 m² were recorded. Flower visitors were grouped into bumble bees (Bombus sp.), honey bees (Apis mellifera), non-Bombus wild bees and syrphid flies. Because of low numbers of visits by non-Bombus wild bees and syrphid flies, only bumble bees and honey bees could be analyzed. The number of inflorescences per m² and the number of visits per taxon were summed over the number of observation rounds per plot (n). For the visit durations of flower visitors on inflorescences single individuals of bumble bees and honey bees within 1 m² were observed for 10 or 15 minutes and the time spent on each inflorescence was recorded and later averaged. Data are aggregated on plot level with n = number of total observed individuals