Pollinator interaction with selected ‘weeds’ flora, Asteraceae, in the context of land use

ABSTRACT Insect pollinators in agroecosystem are not only associated with crop plants but they also interact with weed flora growing there. In this study, the role of four Asteraceae weed flora: Ageratum conyzoides, Bidens pilosa, Caesulia axillaris and Tridax procumbens influencing pollinators’ diversity in three different land-use gradient, uncultivable land ecosystem , semi-cultivated land and cultivated land ecosystem is investigated in Terai Arc Landscape of Uttarakhand state in India. Total 29 species of pollinators belonging to 10 families of 3 orders were observed with these weed floras. Among pollinators Apis mellifera visited all four species, whereas weeds like T. procumbens and C. axillaris showed more association with hymenopteran pollinators. The floral rewards like total number of pollen grains per flower and total sugar concentration (TSC)/ flower (µg/mL) were analysed by principal component analyses depicts that T. procumbens and C. axillaris are potential producers. Weather conditions had an influence, where minimum relative humidity (Pearson correlation, r = 0.88), minimum temperature (r = 0.86), rainfall (r = 0.68) and maximum temperature (r = 0.63) were favourable for the insect pollinators’ visitation during our study. This study demonstrates that all four Asteraceae weed species have the potential to supplement the diet of pollinators within agricultural ecosystem.