Insect light sensitivity caused by newly found endocannabinoid

Most vertebrates produce a special group of molecules known as endocannabinoids. Molecules like 2-AG and anandamide are, however, oddly absent in insects. Researchers recently discovered a different endocannabinoid found in insects causes light sensitivity in fruit flies.

2-LG found in fruit flies

insect light sensitivity by endocannabinoid
Molecular structures of endocannabinoids, 2-LG and 2-AG.

Insects and humans consist of transient receptor potential (TRP) channels that respond to temperature, chemicals, and light. Any connection between these channels and photosensitivity was conversely unknown in insects like fruit flies.

Published in Science Signaling, the study elucidated a previously unknown connection. 2-linoleoyl glycerol (2-LG) — an endocannabinoid-like substance in Drosophila (fruit flies) — orchestrates the link in insects, according to new research. 2-LG is a derivative of linoleic acid, an omega-6 fatty acid.

A lipid scan to locate 2-LG

A few endocannabinoid-related lipids found in fruit flies elevate in response to light. Diacylglycerol levels, a 2-AG precursor, increased in the insect due to photo exposure.

The endocannabinoid did not increase in mice engineered without enzymes required for biological 2-LG production. Researchers found the unique endocannabinoid-like substance in fruit fly heads at 60 to 100 times greater concentrations relative to other lipids. And the stark increase did not occur without light or a functional precursor known as diglyceride (DAG.)

Wavelengths that do and don’t boost lipids

2-LG is a newly found endocannabinoid in insects that causes light senstivity
Photo of 2-LG synthesis and action courtesy of Sokabe et al. 2022.

Different types of light produced different results on endocannabinoid production in fruit flies. Blue wavelengths, for example, affected lipids more significantly than an orange spectrum. Blue light boosts 2-LG levels in fruit flies by greater than 30%. Researchers predicted a local increase as great as 300% in the insect’s eye following the cessation of blue light stimulation.

Cannabinoid receptors are absent in insects. 2-LG is considered an endocannabinoid, although it causes insect light sensitivity by inducing TRP channels. Unique to phytocannabinoids, 2-linoleoyl glycerol triggers a subset of canonical TRPs. This finding affirms that insects utilized unique biological adaptations to survive toxic environments throughout their evolution.

Check out this story to read more about endocannabinoid production in insects.


  1. Sokabe T, Bradshaw HB, Tominaga M, Leishman E, Chandel A, Montell C. Endocannabinoids produced in photoreceptor cells in response to light activate Drosophila TRP channels. Sci Signal. 2022;15(755):eabl6179. doi:10.1126/scisignal.abl6179