Natures wonders: locusts poison birds (Introduction)

by David Turell , Monday, January 28, 2019, 19:31 (2124 days ago) @ David Turell

They carry proteins which will poison birds that try to eat them:

http://advances.sciencemag.org/content/5/1/eaav5495?rss=1

"Many aggregating animals use aposematic signals to advertise their toxicity to predators. However, the coordination between aposematic signals and toxins is poorly understood. Here, we reveal that phenylacetonitrile (PAN) acts as an olfactory aposematic signal and precursor of hypertoxic hydrogen cyanide (HCN) to protect gregarious locusts from predation. We found that PAN biosynthesis from phenylalanine is catalyzed by CYP305M2, a novel gene encoding a cytochrome P450 enzyme in gregarious locusts. The RNA interference (RNAi) knockdown of CYP305M2 increases the vulnerability of gregarious locusts to bird predation. By contrast, the elevation of PAN levels through supplementation with synthetic PAN increases the resistance of solitary locusts to predation. When locusts are attacked by birds, PAN is converted to HCN, which causes food poisoning in birds. Our results indicate that locusts develop a defense mechanism wherein an aposematic compound is converted to hypertoxic cyanide in resistance to predation by natural enemies.

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"In summary, our results reveal an unprecedented antipredator mechanism in the migratory locust. PAN has a dual role in antipredator defense as an honest olfactory aposematic signal and as an indicator of HCN toxicity. The dual roles of PAN increase the resistance of gregarious locusts to predation. The increased predator resistance of locusts, in turn, likely contributes to the development of locust swarms. Genetic engineering strategies for the biological control of locust populations may target the CYP gene that encodes for the rate-limiting enzyme in PAN biosynthesis to eliminate the defense mechanisms of gregarious locusts.

Comment: Hydrogen cyanide is a poison but the locusts tolerate it. Only when they swarm and birds are around do they produce it. How this evolved is an issue since HCN can kill.