Friends or foes?
When spring comes with its glory, your garden quickly gets populated by six-legged residents. You might attribute good or bad roles to most of them immediately, but encountering an unfamiliar insect brings up the question: Is it a friend or a foe?
Pollinators are undeniably friends of humans, as our food heavily depends on their hard work! Also, not only from the human point of view, buzzing from one flower to another indeed provides a good service for the environment too!
Pollination is only one of the benefits we get from insects. Honey and bee wax are produced by honeybees, silk is produced by silkworms, and many insects are used for food and feed, some even in medicine. We tend to consider these insects as friends but introducing them to new environments is not necessarily a good idea, as the following example depicts.
The unexpected consequences of beekeeping
In the last few decades, the hobby of beekeeping has surged, leading to the introduction of honeybee colonies to new regions worldwide. Despite honeybees demonstrating their value as allies to farmers and beekeepers alike, their presence has had negative effects on wild bee populations and plant-pollinator networks. Honeybees are experts at getting nectar and pollen from a variety of different flowers, so they end up taking most of it, creating exploitative competition whereby one species exhausts the available resources, leaving little for others. Moreover, commercial bee colonies frequently carry diseases and parasites. Due to their dense populations and mobility, they can spread these diseases to wild bee populations they encounter. This poses a serious threat to the health and diversity of wild bees and the ecosystems they inhabit.
The enemy of my enemy is my friend
Fear has a pivotal role in shaping our perspective on insects but what you are afraid of is not necessarily bad for your garden. For instance, social wasps are known for joining picnics without being on the guest list and are responsible for some occasional stings. Despite their insistence on getting our food, these insects are remarkable hunters and play an active ecological role in controlling herbivore populations. Therefore, we should avoid destroying their nests and preserve their habitats, such as forests. This is also true for braconid wasps. Although they might not appear as formidable as most familiar wasp species as they lack black and yellow stripes and are much smaller in size, they are still very efficient in reducing pests in our gardens. As parasitoids, they lay their eggs on or in other arthropods, leading to the host's death. Different species specialize in various insects, commonly targeting Lepidoptera, but some focus on beetles, flies, or bugs.
The good, the bad and the ugly
Appearances may deceive! Boring or dangerous-looking insects may be our best friends while beautiful insects may be a big nuisance. How well can you tell friends from foes? Have a look at the gallery below for various examples of harmful and beneficial insects.
The Colorado potato beetle (Leptinotarsa decemlineata): It is considered a pest as it damages Solanum plants which include widely-consumed crops such as potatoes, tomatoes, and eggplants.
The ladybug: In contrast to what their name implies, ladybugs are furious predators of aphids that infest our plants. Both the adults and larvae are active hunters, therefore considered by humans as friends. However, the harlequin ladybird (Harmonia axyridis), which originates from Central Asia and whose eggs are sold as a biological control against aphids all around the world, ranks among the world’s most invasive insects. iIt has turned into a significant pest, endangering native ladybird species by outcompeting, infecting, or preying on them.
The silverfish: Silverfish are stealthy nocturnal animals commonly found in houses. They breed quickly and it is hard to get rid of them. Since they can digest cellulose, they can cause damage to books, photos, wallpapers and textiles.
The dung beetle: Worshiped in Ancient Egypt, dung beetles use mammal dung for feeding and nesting, thereby playing a key role in recycling nutrients into the soil. They benefit ecosystems by dispersing seeds, reducing livestock parasites, and promoting plant growth.
The springtail: Also known as lucerne flea, this insect is considered a pest of bean family (Fabaceae) plants.
The carpet beetle: The larvae of this beetle are considered house pests. They feed on organic materials and can cause serious damage to furniture, clothes, carpets, or musical instruments. They are also famous for infesting entomology collections and feeding on museum specimens.
The lacewing: These delicate-looking insects feed on pollen, nectar and honeydew that are produced by aphids. However, their larvae hunt soft-bodied insects including aphids, spider mites and white flies. Thanks to this predatory service, they are considered as friends.
How many of these did you guess right? To learn more about who is a friend or a foe, check out detailed articles on different insect species below.
References
Valido A et al. 2019. Honeybees disrupt the structure and functionality of plant-pollinator networks Scientific Reports 9:4711. https://doi.org/10.1038/s41598-019-41271-5
McAfee A 2020. The Problem with Honey Bees. https://www.scientificamerican.com/article/the-problem-with-honey-bees/ Accessed 3.6.2024
Bertleff D et al. 2020. Predation and avoidance behaviour in aphid-ladybird interactions of native and invasive ladybirds in Europe. Ecological Entomology 46:41-47. https://resjournals.onlinelibrary.wiley.com/doi/10.1111/een.12938 Accessed 3.6.2024
Jacobs S 2023. Bristletails (Silverfish and Firebrats). https://extension.psu.edu/bristletails-silverfish-and-firebrats Accessed 3.6.2024
Manning P et al. 2021 Dung Beetles Help Keep Ecosystems Healthy https://kids.frontiersin.org/articles/10.3389/frym.2021.583675 Accessed 3.6.2024