Establishing a pollen profile for ‘Apis mellifera ligustica’ bee colonies in the Maltese Islands

Abstract

This study focuses on establishing which floral species encompass the diet of nine Apis Mellifera ligustica honey bee colonies in a central location in Malta. Before the initialisation of the data collection, flower samples were collected to create a personal pollen library to aid with identification of flowering species. The data collection period started on 16/12/2022 and ended on 20/04/2023. Pollen traps were used on a fortnightly basis for 24 hours to collect the pollen pellets, which were then homogenised and stained and observed using light microscopy methods; counts of 500 pollen grains were taken from each hive and sampling date to obtain a representative sample. The main species observed to have over 45% presence throughout the various sampling dates were Convolvulus and Ferula pollen. Secondary species (45% to 16%) included Narcissus, Sinapis, Diplotaxis, Oxalis pes-caprae and Ceratonia siliqua. Important minor species (15% to 3%) included Asteraceae, Sonchus, Euphorbiaceae, Prunus dulcis, Diplotaxis, Crataegus, Acacia, Daucus, Galactites tomentosa, Myrtaceae and Fabaceae. Several other species having less than 3% presence were listed as Minor pollen and included Apiaceae, Tropaeolaceae (Nasturtium), Mercurialis annua, Myrtaceae, Rosmarinus officinalis, Asparagales, Urticacaeae and Silene. It was noted that some hives also collected significantly more pollen than others and that the honey bees preferred a variety of wild flowering plant species. Hive variation was also observed, and two unique clusters were identified in which they were shown to have specific preferences for some species over others. The primary inference that can be drawn from these findings is that the presence of a diverse spectrum of wild floral species is vital to uphold the overall health and functionality of honey bee colonies.