Selenium-tolerant diamondback moth disarms hyperaccumulator plant defense

Area of Science:

• Biogeochemistry
• Ecology
• Evolutionary Biology

Background:

• Plants can accumulate extreme levels of selenium (Se).
• The ecological role of selenium hyperaccumulation in plants is not fully understood.

Purpose of the Study:

• Investigate the role of Se in plant defense against herbivores.
• Determine the mechanism of Se tolerance in insects.
• Explore the ecological implications of Se hyperaccumulation and insect Se tolerance.

Main Methods:

• Field observations of plant-herbivore interactions.
• Laboratory experiments on insect feeding and oviposition.
• X-ray absorption spectroscopy and liquid chromatography-mass spectrometry to analyze Se metabolism in insects.

Main Results:

• Selenium in Stanleya pinnata deters most herbivores but not a specific variety of diamondback moth (Plutella xylostella).
• Se-tolerant moths and their wasp parasite (Diadegma insulare) accumulate methylselenocysteine, unlike sensitive moths that accumulate toxic selenocysteine.
• Se-tolerant moths incorporate less Se into proteins and sequester Se in specific abdominal tissues.

Conclusions:

• Selenium hyperaccumulation can drive the evolution of Se-tolerant herbivores, facilitating Se entry into the food web.
• Understanding Se tolerance mechanisms is crucial for assessing the ecological impact of Se-enriched crops and Se remediation strategies.