Bees (order Hymenoptera, superfamily Apoidea) are among the most important of all pollinators and are frequently seen buzzing about flowers or flying between them in search of food. Adult female bees may drink nectar and eat pollen when visiting flowers, but they primarily collect floral resources for their offspring who completely depend on it for development and survival (Michener 2007). During such visits, bees inadvertently move pollen from flower to flower, which pollinates the plants (i.e. fertilizes them) enabling sexual reproduction.
Male bees also act as pollinators, but they are less effective at it than females. That’s because they don’t actively collect pollen, but instead imbibe nectar for energy and mating, and thus transfer less of it among flowers (Michener 2007).
The importance of bee pollination is huge. Some studies indicate that the value of insect-pollinated crops in the USA alone, most pollinated by bees, ranges from $4.6 to $18.9 billion (Michener 2007), and that the contribution by native bees may exceed $3 billion (Losey and Vaughn 2006). It is likely that the contribution of native bee pollinators in agroecosystems will increase with the observed decline in feral- and managed- honey bee populations due to affliction by parasites and pathogens (Michener 2007).
The importance of native bee pollinators for uncultivated flora is inestimable. Most tree species in tropical regions are bee pollinated (Frankie et al. 1990), as are a great number of small tree species, bushes, herbaceous plants and flowers in temperate regions (Michener 2007).
Habitat loss and fragmentation post a serious threat to all pollinators and the services that they provide. Loss of habitat that provides host flowers and nesting habitat for bees is of great concern for their conservation, as is inappropriate use of insecticides (O’Toole 1993, Matheson et al. 1996).