Hymenopterans

Hymenopterans, such as ants, bees, and wasps are an economically and ecologically significant group of animals. Although these insects are found throughout Saskatchewan, from the mixed-grass prairie in the south to the taiga shield in the north, their biology is poorly understood. Some of the major hymenopteran families in Saskatchewan include the Vespidae (the true wasp family, including yellow jackets), the Apidae (bumble-bees and the introduced honey bee), and the Formicidae (ants). Nearly 103,000 species of Hymenoptera have been identified globally. In Canada, 6,042 species have been identified, and another 10,637 species have been found but not yet described. The number of hymenopteran species in Saskatchewan is unknown, owing to an unfortunate lack of research on this important insect order.

Ants and bees are insects; therefore they have three body parts: head, thorax, and abdomen. The head bears a pair of antennae, the eyes and chewing mouth parts. The thorax bears two pairs of wings and three pairs of legs. The abdomen may bear an appendage called an ovipositor. An ovipositor is a specialized elongated organ that deposits eggs and can also function as a sting. Hymenopterans undergo complete metamorphosis. An individual must go through larval and pupal stages before becoming an adult. Bees feed on pollen and nectar, whereas ants and wasps are omnivorous. They eat other insects, arachnids, seeds, and other pieces of vegetation.

Some bees and wasps are solitary, but many species of hymenopterans are social in nature. Honey and bumble-bees, paper wasps, and ants live in colonies that are comprised mostly of females. Within a single colony, various castes perform specific functions. Depending on the age and size of the hymenopteran colony, each egg a queen lays develops into a worker (female), a virgin queen, or in the case of social bees and wasps, a drone (non-worker male). Generally, male hymenopterans do not perform daily tasks but are essential for the establishment of new colonies because they fertilize virgin queens. Hymenopteran colonies have complicated social systems that rely heavily on pheromones for communication. Pheromones are natural chemicals that evoke a behavioural response from other members of the same species. By brushing their antennae against another individual, ants or bees can recognize others within the colony as either friend or foe. If an intruder is identified, it is communicated to the rest of the colony and the individual is attacked and removed. Honey bees also communicate through physical movements. After returning to the hive from a new source of nectar, individual bees perform a “dance” for the rest of the colony; this dance identifies the type of flower as well as the direction and distance from the hive.

Although physically small in size, hymenopterans play a large role in maintaining healthy ecosystems. Parasitic and predacious hymenopterans act as a natural control of pest species. Not only do bees provide us with honey, they are also essential for the pollination of many plants, including field crops, vegetables and fruits that we and other animals rely on for food. Wildflowers and urban flower gardens are also dependent on insect pollinators. Other hymenopterans such as ants are essential in nutrient recycling. Depending on the species, underground ant colonies may have tens to hundreds of thousands of individuals. These “super organisms” are very effective at turning over soil and cycling nutrients as animal and plant matter is digested and transported throughout the colony. The large number of diverse activities in which hymenopterans play a role illustrates what an important part of Saskatchewan's biodiversity they represent.

Jeanette Pepper

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Further Reading

Borror, D.J. and R.E. White. 1970. A Field Guide to the Insects of America North of Mexico. Boston: Houghton Mifflin; Holldobler, B. and E.O. Wilson. 1990. The Ants. Cambridge, MA: Harvard University Press.