A chemical defense deters cannibalism in migratory locusts

Abstract

Many animals engage in cannibalism to supplement their diets. Among dense populations of migratory locusts, cannibalism is prevalent. We show that under crowded conditions, locusts produce an anticannibalistic pheromone called phenylacetonitrile. Both the degree of cannibalism and the production of phenylacetonitrile are density dependent and covary. We identified the olfactory receptor that detects phenylacetonitrile and used genome editing to make this receptor nonfunctional, thereby abolishing the negative behavioral response. We also inactivated the gene underlying phenylacetonitrile production and show that locusts that lack this compound lose its protection and are more frequently exposed to intraspecific predation. Thus, we reveal an anticannibalistic feature built on a specifically produced odor. The system is very likely to be of major importance in locust population ecology, and our results might therefore provide opportunities in locust management.

Nitrile biosynthesis in nature: how and why?

“…The resistant function of PAN in reducing the substantial risk of being eaten by conspecifics plays an important role in locust population ecology. 202…”

“…The nitrileforming pathway has partially been identied with a cytochrome P450 CYP305M2 (EC 1.14.14.1) catalyzing the transformation of phenylalanine into Z-PAOx in a stereospecic way. [200][201][202] The vulnerability of gregarious locusts to bird predation was demonstrated to be increased aer the knockdown of CYP305M2, and more exposure to intraspecic predation was clearly observed in the CYP305M2 gene knockout mutants. The olfactory receptor LmOR70a, which is necessary for aversive behavior, was proved to be the highly specic and sensitive detector of PAN in the migratory locust Locusta migratoria.…”

“…The resistant function of PAN in reducing the substantial risk of being eaten by conspe-cics plays an important role in locust population ecology. 202 Cyanides produced by cyanogenic pseudomonads exhibit a suppressive effect on plant growth. 232 For example, in plant inoculation studies with cyanogenic Pseudomonas uorescens, reductions in bean growth were observed to be associated with the increasing content of cyanides in the rhizosphere.…”

An effective hydrodynamic description of marching locusts

“…The formation of swarms begins when flightless juvenile locusts form marching bands. Facing challenges in obtaining sufficient nutrients in arid areas and under the risks of cannibalism [14,15], marching bands make long-distance diurnal marching bouts. Field observations describe bands moving in a highly coherent direction and maintain relatively defined structures of columnar streams and planar fronts [16][17][18].…”

A Core Structural Protein That Builds the Locust Mandible with a Mechanical Gradient

“…The migratory locust ( Locusta migratoria ) is one of the most destructive pests in the world and consumes large amounts of relatively hard grass during its lifetime (Figure a). , The mandibles are armed with specialized cuticles of high stiffness and abrasion resistance . Similar to squid beaks, locust mandibles also have a mechanical gradient from the base to the tip regions, with water, chitin, protein, and catechol-containing compounds as the major chemical components .…”