Hoverfly visiting a viper’s bugloss flower. Photo: imagebrokermicrostock, depositphotos
By Victoria Baeker
Plants and bugs* have a long relationship; they have evolved together for millions of years! While it may be annoying to see pests in your garden, your plants may actually want some of them. In this post, let’s explore why plants attract bugs and why some plants attract more harmful insects than others, along with the botany of plants and their relationship to bugs.
*In this article, we use “bug” in a broad sense to mean all kinds of small creatures: insects, other arthropods, worms and many others.
You may have noticed that all plants don’t attract the same insects. Some plants even make powerful chemical substances to repel insects. However, insects like bees, ladybugs, and lacewings stick around.
Some insects serve beneficial purposes like pollination. Bees are desirable for pollinating gardens, and you can get some honey on the side. Plants have evolved ways to attract bees and other pollinators like the bright colors of petals, sweet scents, and nectar. Labiate flowers have large petals providing a landing platform for bees.
Some flowers even bloom at different times of the year so that pollinators have enough food throughout the year and don’t compete with each other. This strategy maximizes the plant’s chances of survival.
There are many pests still capable of destroying farms full of produce. Most plants grown for food evolved in ways that leave them defenseless against these pests. The problem arises when the pest infestation is large enough to decimate plant populations. You may need to use some pest control methods to curb them.
Many small bugs are attracted to areas with high humidity because they have difficulty retaining moisture. Others, like mosquitoes, lay eggs in stagnant water. Due to climatic conditions, overwatering, or waterlogging, the humidity may be high.
Healthy soil tends to have a natural balance of nutrients, moisture, and aeration that supports sustainable populations of microorganisms and bugs. Poor quality soil loses its natural ability to keep the pests at bay due to the disruption in the balance of beneficial arthropods. This disruption is due to an imbalance in the soil’s pH or high salinity levels.
As gardening enthusiasts, insects are essential to us. Even bugs like termites, ants, and earthworms are helpful and a necessary component of healthy topsoil in their native environments. When the balance is upset, problems crop up, and pests ruin your home, farm, or garden.
Termites, for instance, are natural inhabitants of forests, but you don’t want them holing up in the walls of your home. Springtails are harmless in the garden, but an infestation in your basement can be annoying.
Farmers and gardeners are naturally interested in finding companion plants, some of which have shown promising potential in discouraging pests. Nature also has an arsenal of natural insecticidal compounds produced by plants.
The most common mechanism for plant pest resistance is producing toxic compounds ranging from sesquiterpenes to allicins. It’s how plants like basil, marigolds, and plants from the genus Allium keep some pests away. The compounds are volatile and have different mechanisms like irritating the membranes of pests, interfering with their pheromones, etc.
Finally, it is worth mentioning that some GM (genetically modified) plants contain a gene for insect resistance imported from the bacteria Bacillus thuringiensis. Crops that carry the Bt gene produce a toxin that solubilizes pest guts.
However, there is quite a lot of misinformation floating around about the capabilities of companion plants to repel insect pests. Most plants are not resistant to all pests. While even the more resistant ones may repel some pests, they can still be attacked by others. Insects have been co-evolving with plants and come up with great defenses against plant’s protections.
Milkweeds and foxgloves produce compounds called cardenolides that bind to the sodium pump of the cells of the insect and shut it down, causing lethal cell damage. Monarch butterflies, however, have a mutation in Na/K-ATPase gene, reducing cardenolide binding efficacy. So, they can feed on these plants without dying.
If you catch a pest infestation in its initial stages, you may be able to get rid of the bugs with simple measures like dousing the plants with a mild soap solution or spraying a natural insecticide. A more severe infestation can be harder to eliminate. The pest control strategy should take into account the following factors:
1. Why you’re growing the plants
You may be gardening to get yields of fresh produce or to wow people with a zen-style garden. If it’s the former, you’ll have to be very careful about the kinds of insecticides used, because the plants should not become unfit for consumption.
2. The garden’s aesthetics
You would’ve put a lot of thought into the look of the garden, deciding where to have trees, shrubs, flowers, hedges, etc. It may turn out that eliminating pests for good could mean that you won’t be able to grow certain plants at all.
3. Proximity to your home
The pest control methods should not chase garden pests towards your home, and vice versa. If you’re having a home infestation, your garden should be kept safe.
4. How dangerous the pest is
Some bugs aren’t harmful to people; they are just a nuisance, but others (even beneficial ones like bees) can be dangerous. Quick and effective methods would work better for such pests.
If you have an expensive lawn and see pests attacking the grass, calling in professional pest experts specializing in lawn care would be best.
Prevention is best, and that is why you should make sure that you’re providing optimal conditions for plant growth but not accidentally encouraging pest proliferation.
About the Author
Victoria Baeker is the Sr. Editor at HomeWarrantyReviews.com. She enjoys finding ways to minimize her living costs and is a garden enthusiast. While she specializes in finance and insurance, she also likes to write long rants about books and movies. The COVID pandemic deprived her of her usual thrill-seeking hobbies, so she turned to day trading for that adrenaline rush.