A chemical defense deters cannibalism in migratory locusts

Abstract

Many animals engage in cannibalism to supplement their diets. In swarms of migratory locusts, cannibalism is prevalent and thought to be an important factor for swarm dynamics. We show that in dense swarms, locusts defend themselves by producing an anti-cannibalistic pheromone; phenylacetonitrile (PAN). Both the degree of cannibalism and the production of PAN are density dependent and co-vary. We identify the olfactory receptor responsible for the detection of PAN, and by using genome editing we show that by making this receptor non-functional we abolish the negative response to PAN. We also knock out the gene underlying PAN production and show that locusts lacking PAN lose its protection and are more frequently exposed to intra-specific predation. In conclusion, we reveal an anti-cannibalistic feature built on a specifically produced odor. The system is very likely of great importance in locust swarm dynamics and our results might therefore provide opportunities in locust management.

Diverse strategies that animals use to deter intraspecific predation

“…Thus, this raises an important question as to whether the evolutionary consequences of intra and inter‐specific predation and the respective defence strategies against them that animals use are the same or are they really different. Given that there is some evidence that animals can use the same chemical compound in defence against both intra‐ and inter‐specific predators (Hansson et al, 2022; Wei et al, 2019), this question warrants further research.…”