Warming weakens natural enemies of insects, new research shows

A warming climate is disrupting the delicate balance of nature. An international team of scientists led by entomologists from the Biology Centre of the Czech Academy of Sciences has found that higher temperatures significantly reduce the success of parasitoids – tiny wasps that help regulate insect populations in nature. This is also bad news for farmers, who rely on these wasps as part of plant protection against insect pests. The study was published in the prestigious journal Ecology Letters.

Parasitic wasps lay their eggs in or on the bodies of other insects. Their larvae then develop inside the host, feeding on it and eventually killing it. In this way, parasitoids act as an invisible control force regulating populations of insect pests. They help maintain balance not only in natural ecosystems but are also widely used in agriculture, particularly in orchards, fields, and greenhouses during fruit production.

However, the new study shows that this role of parasitoids may weaken as temperatures rise. Researchers experimentally examined 28 different interactions between parasitoids and their hosts at an ambient temperature of 24 °C and under warming by four degrees to 28 °C. At higher temperatures, the developmental success of parasitoids dropped sharply, and their “diet” narrowed – they were able to attack fewer host species. The hosts themselves, by contrast, were much less affected by warming.

“This means that the balance between insects and their natural enemies is breaking down. Parasitoids are losing the ability to respond flexibly to changes in host availability,” explains the study’s lead author, Jan Hrček from the Biology Centre of the Czech Academy of Sciences.

The research included four tropical parasitoid species and seven host species. “The parasitoids responded in a very similar way, even though we selected evolutionary lineages older than the dinosaurs. Given their tropical origin, one might expect them to cope well with higher temperatures, but that is not the case. It is therefore likely that this is not an exception, but a general biological phenomenon,” Hrček points out.

The scientists also tested the opposite scenario, lowering the original temperature by four degrees. Cooling to 20 °C had only a mild effect on both parasitoids and their hosts, confirming that warming represents the major risk.

Parasitoids are an important component of plant protection against insect pests. If their role is weakened by rising temperature, pest populations may increase. This could lead to greater agricultural losses, increased reliance on chemical pesticides, and further disruption of ecosystem stability. The study thus shows that the climate change impacts not only the survival of individual species, but also the functioning of entire food webs.

Publication:

Lue, C.-H., M. Thierry, L. R. Jorge, N. A. Pardikes, M. Higgie, and J. Hrček. 2026. “ Warming Reduces Parasitoid Success and Narrows Their Diet Breadth.” Ecology Letters 29, no. 1: e70322. https://doi.org/10.1111/ele.70322.

Contact:

Mgr. Daniela Procházková
PR manager
Biology Centre of the Czech Academy of Sciences
daniela.prochazkova@bc.cas.cz

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