At least half of the insect species on Earth feed on plants. Some pests threaten plant and crop health in certain areas – especially in cities. Dozens of studies show that plant pests and sucking insects thrive in urban areas. Natural predatory enemies are not waiting for them there.

Plant Pests Thrive in Cities

Sufficient biodiversity is what provides insect control. Predatory insects, natural enemies of plant pests, and annoying sucking insects are essential to ecosystems. However, urbanization disrupts these ecosystems. There are fewer insect predators in cities than needed; it naturally leads to an overgrowth of pests, for example, aphids.

Aphids. Image by FRANCO PATRIZIA from Pixabay

A global study published in the Science of the Total Environment answers questions on this topic. The Center for Ecological Research in Hungary and the Technical University of Munich in Germany participated in a study examining the impact of urbanization. The researchers used a meta-analysis approach that allows the results of several scientific articles dealing with the same issues to be combined and evaluated.

Insect Predators Need Support

Researchers identified 52 studies conducted in various cities around the world. They found that “compared to rural areas, urban areas increase the number of biting and sucking insects, such as aphids and scaly insects, by about 44%. But, on the contrary, the number of natural enemies with low scattering capacity is lower there, “says INRAE, the research member.

Ladybugs breed on aphids. Image by jggrz from Pixabay

The results of the meta-analysis suggest that increasing levels of urbanization are leading to a decline in the level of biological control provided by natural enemies. For example, spiders, ladybugs, and parasitoid wasps, which help reduce plant-eating insect populations, are not doing very well in cities. That is why we often encounter insect pests and biting and sucking insects.

There are ways to promote biodiversity in urban areas. Cities can establish vegetation zones – tall grasses, shrubs, and trees. If the grass is cut, all plant products must be left in the place to provide shelter and favorable conditions for natural insect predators.

Source and credit:, featured photo by Henry Lai on Unsplash