Hatchlings from wet (left) and desiccated (right) large eggs. Credit: Koutaro Ould Maeno.

In dry conditions, locusts have undersized babies – with their first lunch already in their guts, according to new research.

Desert locusts have two distinct modes – solitary and gregarious – that are behaviourally and visibly different.

The insects also live in the Sahara Desert, an environment with frequent dry conditions.

Koutaro Ould Maeno, of the Japan International Research Centre for Agricultural Sciences, and colleagues explored how a lack of moisture and the presence of other locusts shift reproductive resource allocation in the insects.

In lab experiments, the authors raised locusts in crowds and in isolation. Crowd-reared females produced fewer, larger eggs than females raised in isolation; large offspring likely have an advantage when there’s competition for food.

For both types of locusts, dry conditions produced smaller hatchlings than wet conditions, and the hatchlings in dry conditions were born with a small amount of yolk in their guts – what is known as the ‘lunchbox strategy’.

With their first meal taken care of, these babies have a bit more energy and time to find plants to eat than hatchlings born with empty stomachs.

For solitary locusts, dry-condition small hatchlings lived 65% longer than normal-sized hatchlings in starvation conditions and hatchlings from desiccated gregarious eggs survived 230% longer than those from wet solitarious eggs in the same conditions.

According to the authors, the results illustrate the complex ways female locusts and embryos living in an unpredictable and harsh ecosystem allocate their reproductive resources. 

The research is published in PNAS Nexus.