Selenium hyperaccumulation reduces plant arthropod loads in the field

• Published in: The New phytologist Vol. 177; no. 3; pp. 715 - 724
• Main Authors: Galeas, Miriam L, Klamper, Erin M, Bennett, Lindsay E, Freeman, John L, Kondratieff, Boris C, Quinn, Colin F, Pilon-Smits, Elizabeth A.H
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.01.2008; Blackwell Publishing; Blackwell Publishing Ltd
• Subjects: Animals; Arthropods; Arthropods - physiology; Astragalus americana; Astragalus bisulcatus; Biological Evolution; Brassicaceae - metabolism; Brassicaceae - parasitology; Camelina microcarpa; Descurainia pinnata; Ecosystem; elemental defense; Fabaceae - metabolism; Fabaceae - parasitology; Feeding Behavior - physiology; Helianthus - metabolism; Helianthus - parasitology; Helianthus pumilus; Herbivores; Host-Parasite Interactions - physiology; Hyperaccumulator plants; Hyperaccumulators; Medicago sativa; Phytoremediation; Plants; Predators; Selenium; Selenium - metabolism; Stanleya pinnata; Surface areas; T tests
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2007.02285.x

The elemental defense hypothesis proposes that some plants hyperaccumulate toxic elements as a defense mechanism. In this study the effectiveness of selenium (Se) as an arthropod deterrent was investigated under field conditions. Arthropod loads were measured over two growing seasons in Se hyperaccumulator habitats in Colorado, USA, comparing Se hyperaccumulator species (Astragalus bisulcatus and Stanleya pinnata) with nonhyperaccumulators (Camelina microcarpa, Astragalus americanus, Descurainia pinnata, Medicago sativa, and Helianthus pumilus). The Se hyperaccumulating plant species, which contained 1000-14 000 μg Se g⁻¹ DW, harbored significantly fewer arthropods (c. twofold) and fewer arthropod species (c. 1.5-fold) compared with nonhyperaccumulator species that contained < 30 μg Se g⁻¹ DW. Arthropods collected on Se-hyperaccumulating plants contained three- to 10-fold higher Se concentrations than those found on nonhyperaccumulating species, but > 10-fold lower Se concentrations than their hyperaccumulator hosts. Several arthropod species contained > 100 μg Se g⁻¹ DW, indicating Se tolerance and perhaps feeding specialization. These results support the elemental defense hypothesis and suggest that invertebrate herbivory may have contributed to the evolution of Se hyperaccumulation.