Cocooned Wasp Larvae Jump to Find Cool Spots, and to Protect Themselves

The larvae of a parasitoid wasp called Bathyplectes anurus are known to spin cocoons and jump five centimeters while inside of them. Now scientists may have discovered why, according to a paper published in The Science of Nature.

It seems like they jump to find a shady spot. Lead researcher Yoriko Saeki and her team examined the effects of different light intensities, temperatures, as well as levels of humidity under different laboratory and field conditions while conducting experiments on 100 Bathyplectes anurus larvae to understand if this behavior is a survival technique, and whether it comes at a cost to the insects.

The cocoons that were exposed to light jumped nearly three times more often than those kept in darkness. Jumping activity increased during rapid temperature increases, and was 60 percent higher at conditions of low humidity. When the cocoons were allowed to jump freely in an area of gradient light going from dark to bright, more cocoons ended up in shady areas. Cocoons in the shady area were more likely to survive, compared to the cocoons left out in brighter light.

The cocoons also jumped and moved about 83 percent more when they were placed near Japanese giant ants, known predators of this type of larvae, compared to when there were no dangerous elements in the vicinity. The frequency of movements decreased once the predators made direct contact with the cocoons.

The results suggest that the larvae respond to environmental stresses by jumping to more favorable habitats that allow them to develop unrestrictedly. The body mass of the individuals that jumped was lower compared to those that did not. The researchers suggest that this is because jumping behavior comes at a cost as it requires more energy use.

Read more at:

Costs and benefits of larval jumping behaviour of Bathyplectes anurus

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