We know about the fascinating behaviours of honey bees (Apis Mellifera), which are managed worldwide for pollination and honey production. Still, we don’t know much about ‘wild’, free-flying, ‘solitary bees’.
They range from the miniscule (2 mm) solitary Perdita Minima, known as the world’s smallest bee, to pecan nut-sized species of Carpenter Bees.
Solitary bees, comprising about 90% of the over 20,000 known bee species, are a crucial but often overlooked component of ecosystems. Solitary bees perform much of the pollination in natural ecosystems and are better at pollinating some crops, partly because some species can buzz-pollinate flowers.
Solitary bees face challenges, including declining populations attributed to ecosystem health decline and increased demand for crop production and, in some areas, being outcompeted by honeybees when it comes to foraging for pollen and nectar.
Unlike honeybees, solitary bees do not build hives, live in colonies, produce honey, swarm, tend to their young or have queens. Instead, they collect pollen, mix it with a small amount of nectar and leave it in individual cells for the larva to feed on when it emerges from the pupating stage. Solitary bees have unique characteristics like long antennae and side-positioned eyes. They cannot hover. They vary in size from the tiny 2 mm Perdita Minima to pecan nut-sized Carpenter Bees. They find essential nectar and pollen resources in wildflowers.
Approximately 70% of solitary bees are known as Mining Bees as they nest underground, using mud to cap their nests. Solitary bees use all sorts of materials to make their homes – for example, Leafcutter Bees cut out tiny pieces of leaves to line their nests, which might be in a hollow plant stem, dead wood or a crack in a weathered wall. Carpenter bees make their nests in tunnels in hardwood, logs, stumps, or the dead branches of trees. Wool Carder bees use fine plant hairs to line their nests in hollow plant stems.
Solitary bees collect pollen from various plant species, contributing to plant reproduction and seed production. Some solitary bees specialise in pollinating plants we use for food, such as squashes, pumpkins, gourds, and sunflowers. They don’t have ‘pollen baskets’ like honeybees and lose pollen during each flower visit, making them exceptionally efficient pollinators. A single red Mason Bee is said to be equivalent to 120 honeybees in the pollination service it provides.
Overall, solitary bees play a significant role in pollination. They are either the primary pollinators of almost all crops or significantly supplement honeybees’ activity. Solitary bees also provide a vital ecosystem service by ensuring healthy and productive plant communities.
Protecting and enhancing bee pollination is crucial for global food security and environmental balance. It is important to note that while honeybees are essential for pollinating some crops, they can also hasten the decline of solitary bees by outcompeting them in foraging. This means the intensive introduction of honeybees in conservation areas harms native plants and solitary bee conservation efforts.
Maintaining solitary bee diversity is a priority for preserving ecosystem function and promoting pollination stability and productivity in agroecosystems. The decline in solitary bee populations underscores the need for conservation efforts to ensure ecosystems’ continued health and productivity. Solitary bees are not only fascinating in their behaviours and diversity but also essential contributors to the delicate balance of our environment. Solitary bees, not honeybees, need saving.
