I chose this pairing to contrast a species that people love with one that people hate. I could equally have chosen the giant panda and the common wasp – there are many examples of both categories. 

Honeybees

• The western honeybee, Aphis melifera, is one of over 20,000 bee species in the world. About 250 of these are found in the UK. 
• Honeybees make honey from pollen and nectar. 
• They live in large colonies with one queen, many sterile female workers and some male drones. There can be up to 50,000 bees in the colony. 
• When a new queen emerges, she leaves the hive to mate (having killed any sister queens who emerge after her). When she gets back to the hive, she kills the old queen with help from the workers. Alternatively, the old queen may already have left with a swarm of workers to form a new colony. Learn more about queen bees.
• Queens live for several years, but summer-born workers live for only a few weeks. Males (known as drones) don’t do any work in the colony, and are thrown out of the hive in autumn and left to die. The queen and workers that are born in the autumn usually survive the winter in the hive by huddling together, and eating stored food. 
• Honeybees were native to Europe, Africa, and the Middle East, and have been spread around the world by humans. 
• The amazing symbiosis between humans and honeybees goes back many millennia. 
• There are honeybees still living in the wild, particularly in Africa, but most live in hives tended by people.
• Humans have changed honeybee genetics by breeding them so they are calmer and make more honey. It’s even possible to artificially inseminate a bee under a microscope! There are lots of videos on YouTube showing this process.   
• Globally, their numbers continue to increase, and it’s all thanks to humans. Numbers of hives have almost doubled since the 1950s. However, this increase has been very uneven, and in recent decades has mostly occurred in Asia. In some countries, such as Germany and the USA, numbers are even declining. In many places beekeepers are having to work harder to keep the numbers up, particularly because honeybees face problems with parasites, disease and climate change. Advanced students may want to explore this themselves by drawing graphs using FAO stat. 
• Find out more from the British Beekeepers Association.

Hairworms

• Hairworms are also called horsehair worms, hairsnakes, Nematomorphs or gordian worms. They’re closely related to nematode worms, not to earthworms.
• Most species are 5-10cm long, but the largest species can grow up to 2m (all tangled up inside a cricket or grasshopper).
• Around 350 species have been described by scientists, although there are an estimated 2,000 species in total – most are undiscovered because we dedicate so little effort to studying them. 
• All hairworm species are parasites, and infect different hosts. The lifecycle in my PowerPoint is for a Gordionus sp. hairworm found in Japanese streams. The adult worms mate and lay eggs in water. The worm larvae infect then infect insect larvae living in the stream, such as mayflies. Mayflies spend most of their lives as larvae living in the stream, only flying free as adults. The adults live for just a few hours or days, but when they die the worm inside them doesn’t die immediately. If the dead mayfly is eaten by a cricket, the worm can go on to develop inside it. Hairworms don’t have mouths, but instead absorb nutrients through their skin. They don’t kill the cricket, but amazingly they affect its behaviour. Infected crickets are 20 times more likely to jump into water – not an environment they can survive in. This is how the hairworm returns to the water to complete its lifecycle.
• The worm wriggles free of the cricket when it enters the water – there are great videos. 
• Watch a video explanation of the hairworm lifecycle. 
• Find out more on the Wildlife Trusts website. 
• Read about a mystery of hairworm evolution. 

Points to consider

How do honeybees and hairworms affect other species? 

There are still debates about what impact honeybees have, and it varies with location. There are some positives. Honeybees are food for birds, and for mammals such as bears and honey badgers. Some wild plants are pollinated by honeybees, and this can be particularly important when there is a shortage of wild pollinators. 

However, not all flowers are pollinated by honeybees – some plants rely on species with longer tongues, for example. In some instances, honeybees compete with other bee species for nectar and pollen. This is particularly true in New Zealand, for example, where honeybees have been introduced by humans. 

Viruses have become a huge problem for beekeepers, and there is evidence that honeybees can pass diseases to bumblebees and other closely-related species. Some people are calling for a reduction in the number of hives, particularly in nature reserves and cities.

It may come as a surprise that parasites such as hairworms can have a positive impact on other species. For a start, hairworms can benefit fish – infected crickets that jump into water are an important source of food. In Japan, these crickets can provide up to 60% of the diet of the kirikuchi char, an endangered subspecies of a trout called the whitespotted char. Surprisingly, mayflies may benefit too, even though some get parasitised. If the char wasn’t eating crickets, it would rely more heavily on the larvae of mayflies and other insects. 

How do they affect humans?

Honeybees are of great cultural importance, and bring particular pleasure to beekeepers. Honey is a popular food, and for some people this is their livelihood. Keeping honeybees can be particularly important for people in developing countries. 

Honeybees are of course pollinators. Insect-pollination is particularly important for high-value, nutritious (and delicious!) foods such as fruit and beans. This is valuable for our food supply and many farmers’ livelihoods. However, people often over-estimate the value of pollination. The common statistic that bees are responsible for one in every three mouthfuls of food is false – the likely figure is about 5-8%. Part of the confusion is that crops such as oilseed rape have their yields increased by pollination, but they would still produce some crop without pollination. Estimates are also very vague because we lack the data, particularly because there is so little research on pollination in the developing world. 

Honeybees also take too much of the credit for pollination – they should share the glory with wild bees, flies, moths, wasps, beetles, bats and more. This is very hard to estimate, but studies suggest that bees (including honeybees) are about as important as non-bees for pollination. Recent studies have shown how efficient moths are as pollinators. 

Hairworms don’t have the same obvious direct benefits to humans, but no doubt there are many benefits we don’t know about. This hairworm story shows how little we know about nature, and how complex it can be to understand the impact that species have. Maybe hairworms can increase populations of fish we eat, for example. The future is also hard to predict. Maybe the kirikuchi char will be better able to withstand a new disease than other whitespotted char subspecies. We just don’t know. 

There are clear examples of parasites increasing crop yields. Parasitic wasps are particularly important for pest control, laying their eggs inside caterpillars or other pest insects. Cassava in Thailand provides a particularly striking example. 

What would be the broader impact of any conservation measures?

The best way to increase the number of honeybees is to train beekeepers, but this doesn’t directly benefit other species. However, honeybees and other insects would benefit from more flowers, so increasing wildflower habitats could be a way to help honeybees and bring wider benefits. We can mow lawns and verges less often, for example, and encourage unloved species such as dandelions to grow. 

Hairworms in Japan are declining because forest ecosystems are being replaced by timber plantations. Many species would benefit if we reversed this trend, but what would the impact be on people? This is a good chance to think about how our consumption can leave less space for nature, but also how land can be used in ways that enhance our lives. Some of that timber is no doubt used to build people’s houses, so it isn’t as simple as saying ‘get rid of the plantations’. How do we decide what an appropriate level of consumption is? How can we make this fair?