Applied Entomology and Diversity

Taxonomic diversity

Bees are a much more diverse group than most people realize. There are over 20,000 described species, and most of these have little in common with the European honey bee (Apis mellifera L.). Honey bees are well-known for living as a colony, with a queen and workers, in hives inside trees, logs or man-made boxes. And of course for making honey. Most bees don't do any of this. A typical bee lives a solitary life, and digs an underground nest, which is provisioned with nectar and pollen, but no honey.

Since many bees other than honey bees are important for pollinating wildflowers and agricultural crops, it is important for us to understand and appreciate how most bees live. To this end I have participated in studies of bees in natural areas (such as parks and reserves) and agricultural settings (like apple orchards and blueberry fields).

The diversity of bee behaviour

Many bees live in underground burrows which they excavate. Others nest in pre-existing cavities and line their nests with a variety of substances (e.g., resins, mud, leaves, flower petals). Bees may also nest in rotten logs, pithy stems, snail shells, rodent burrows, termite mounds, and your front porch!

Unlike hive nesting honey bees, most bees are solitary. A single female builds and provisions a nest with pollen and nectar for her young. Solitary bees live only a year, often spending most of that time as a larva or pupa underground. Other bees are more social, preferring the company of others. In some cases, multiple females will share a nest but each will work to provision brood cells and lay her own eggs. These bees are referred to as communal. Their nests are like apartment buildings, with a shared entrance but independent residences. Some bees are very social, with worker bees and a queen similar to the honey bee scenario. Often the queen is the mother of the workers, and only she lays eggs, while her daughters forage for pollen and nectar to provision the nest. This reproductive division of labour is known as eusociality ('true' sociality). The honey bees (tribe Apini) and stingless bees (tribe Meliponini) are highly eusocial, with queens incapable of surviving without her workers. In contrast, bumble bees and some sweat bees have eusocial colonies which are renewed each year by a single female working independently on a nest until her workers are born. The sweat bees also have colonies where the queen and workers are sisters; this is known as semisociality.

A large number of bees refuse to build nests or collect pollen at all. These bees instead enter the nest of a host bee and lay their eggs on the pollen and nectar collected by their hapless victims. These bees are known as cleptoparasites or cuckoo bees. But don't think these bees are lazy! They still must work hard to find nests and in some cases must fight their angry hosts. This is a behaviour which has evolved many times in the bees. Cleptoparasites are usually highly modified, having lost structures used in nest construction and pollen collection. They often have thick cuticle for armour and powerful stings.

Many bees are indiscriminate in their floral visitations, but others are more discerning, preferring one or a few closely related plants for their pollen. The former type are referred to as polylectic bees and the latter, more choosy bees, are called oligolectic. Some bees have no choice but to be polylectic because their long adult life means they outlast the bloom time of an individual plant host. Oligolectic bees can often appear rare if you don't know where to look. Their host preferences make them more susceptible to anthropogenic change because of their reliance on a particular flower. And sometimes even if the host plant is present thee bees are nowhere to be seen.

There is much to be discovered about how this fascinating diversity originates and is maintained. A better understanding of bee diversity will also help us conserve these interesting insects since not all bees are expected to react the same to environmental changes.

Integrated Crop Pollination

"the combined use of different pollinator species, habitat augmentation, and crop management practices to provide reliable and economical pollination of crops"

My current research is examining how pollinator diversity affects pollination of specialty crops in the United States and Canada. I am trying to determine the important pollinators of highbush blueberry (Vaccinium corymbosum L.) and the factors affecting their abundance. An early contribution to this effort found different factors affecting the abundance of wild bees in two areas of blueberry production and different bee species making the major contributions to pollination. Read more here. The influence of habitat surrounding blueberry fields, pest management practices, alternative floral resources, and weather are all being investigated as factors affecting pollinator diversity. Pollination experiments are being used to link bee richness and abundance to crop productivity. The effect of alternative managed pollinators, specifically the bumble bee Bombus impatiens Cresson and the benefits of wildflower plantings are also being studied. For more information on this project see www.projecticp.org.

Above. The nest of Lasioglossum subviridatum, located under the bark of a fallen tree. The soft underbark is a texture similar to soil. Individual cells are made within this substrate with surrounding tunnels. Three nearly mature larvae and one egg on a pollen mass can bee seen.

Above. Not all bees build nests. The female Lasioglossum lionotum above is a social parasite of another sweat bee, L. imitatum. Cleptoparasitism and social parasitism has evolved many times in the bees, and at least six times in the genus Lasioglossum.

Above. Some bees are generalist floral visitors, but Dufourea monardae, as the name suggests, is a specialist on the plant genus Monarda.

Above. Andrena vicina rests on the outside of a blueberry flower. The pollen this bee deposits on the flower's stigma will fertilize the ovary, leading to the development of a delicious berry.