In high temperatures, male desert locusts act as “parasols” to protect the females’ eggs

by Japan International Research Center for Agricultural Sciences (JIRCAS)
September 20, 2024

In collaboration with the Mauritanian National Center for Desert Locust Control, JIRCAS has chronicled the daytime egg-laying behavior of adult desert locusts (simply referred to here as locusts) in a harsh desert environment with extremely high temperatures.

Field surveys in the Sahara Desert revealed that many adult locusts collectively laid eggs at night. However, some females delayed laying eggs, and laid eggs on the ground near the daytime lethal temperature (over 50°C), when most animals avoid activity. In high temperatures, males were found riding on the backs of many egg-laying females, and when the body surface of the locusts was measured using a thermal imaging camera, it was found that they maintained a lower body temperature than the ground surface. When locusts were experimentally exposed to sunlight and their body temperatures were measured, the researchers found that the body temperature of single females became high, but that of paired females stayed low. This led to the idea that the males riding on the females’ backs functioned like a “parasol” to avoid high temperatures and lay eggs.

Grasshoppers have a physiological high tolerance to heat (approximately 55°C), and the males act as a “parasol,” allowing them to lay eggs at times when most animals are unable to be active due to the high temperatures.

From a pest control perspective, pairs of grasshoppers that are mass-laying eggs remain in place for several hours, which increases the efficiency of pesticide spraying. It is hoped that applying this knowledge will lead to pest control that does not use pesticides more than necessary and is environmentally- and health-conscious.

The results of this research were published in the journal Ecology.

Keep reading (in Japanese): https://www.jircas.go.jp/ja/release/2024/press202413

Read the Ecology paper: https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.4416