Ants, Bees and Wasps: Over 600 UK species – and counting!
Speaker: Mike Edwards (Entomologist)
The Hymenoptera constitutes one of the largest insect Orders. It includes the sawflies, the aculeates and an assortment of groups lumped together as the “Parasitica”. The aculeates include the most familiar hymenopterans – the bees, wasps and ants – and this was the topic for this talk by a UK authority on these fascinating insects. His subtitle “over 600 UK species – and counting!” indicated the magnitude of the subject.
Although the talk proceeded systematically through the range of aculeates, we learnt not so much about how to tell them apart, but their extraordinary life strategies and ecological interactions. The aculeates include the social wasps, bees and ants, making them arguably the most advanced insects and leading to the concept of the colony being a “hyper-organism”: the specialised roles of individuals in the colony, with many not fertile, being analogous to specialised cells in a multicellular animal. Sophisticated colonial behaviours in UK ants include farming fungi on woody debris and farming aphids. Aphid management is often underground, with aphids tapping into roots and encompassed by the ant nest. Also technically sophisticated is the warfare between colonies that can result in the capture of workers: there is a species called the Slavemaker Ant!
Bee and wasp nests are provisioned with protein-rich food for larvae, and this involves some specialised predation. For example, Sand Wasps find caterpillars, and Bee Wolves capture honeybees. The prey item is typically immobilised but not killed (so that they stay fresh!) by injected chemicals, and this is the origin of the sting used for defence in social bees and wasps. The black-and-yellow striping of stinging wasps has evolved as a signal of danger, so that birds learn to avoid taking them, but there are many harmless insects that mimic this pattern (Batesian mimicry), hence people become alarmed by hoverflies and the like.
A significant number of aculeates are “cheats” that lay their eggs on the food stores of other bees: cuckoo bees violently take over the nests of social bumblebees and nomad bees lay eggs in the nests of mining bees. Mike showed the distinctive plugs of resin made by Passaloecus wasps to protect their nests in holes in pine trees: he said they look like mini-Stonehenges!
Mike did not neglect to mention the wasps that can be pests on farms and how they are sensibly controlled, but the value of aculeate hymenoptera – wasps as well as bees – in pollination of crops is well known, so it is important that we understand and protect them. Each species has its own ecological story, and Mike did a great job of introducing us to this fascinating and complex topic.