Mirror Image Pheromones Help Beetles Swipe Right

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Researchers have discovered how Japanese scarab beetles, a major agricultural pest, use mirror-image pheromones to attract mates and prevent interbreeding with closely related species. The findings could lead to better monitoring and control of these invasive beetles.

Why it matters

The ability of these beetles to distinguish between mirror-image pheromones has been a long-standing mystery. Understanding this system could help develop new tools to track and manage these damaging agricultural pests, which are difficult to study directly due to strict quarantines.

The details

The researchers found that in the Japanese beetle, Popillia japonica, the R-form of the pheromone japonilure attracts males, while the S-form repels them. In a closely related species, Anomala osakana, the opposite is true - the S-form attracts and the R-form repels. This likely evolved to prevent mating attempts between the species. The team then identified the receptor genes in another related pest, Anomala corpulenta, that allow the beetles to distinguish the two pheromone forms. They then found similar receptor genes in the highly quarantined P. japonica.

• The Japanese beetle, Popillia japonica, was discovered as a major agricultural pest in 1977.
• In 1997, researchers discovered that a different scarab beetle, Anomala osakana, uses the opposite pheromone forms to attract mates.

What they’re saying

What’s next

The researchers hope to use pheromones as tools to monitor and control populations of these invasive beetles. In California, detecting airborne pheromones could supplement traps and inspections as indicators of pests that have snuck aboard an airplane or ship. In places where the beetles are established, pheromones could be used to monitor populations and the breeding cycle. Finally, artificial pheromones might be used to disrupt mating.