Selenium hyperaccumulation reduces plant arthropod loads in the field.
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 microg 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 microg 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 microg 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.
Galeas
Miriam L
ML
Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
Klamper
Erin M
EM
Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
Bennett
Lindsay E
LE
Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
Freeman
John L
JL
Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
Kondratieff
Boris C
BC
Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO 80523, USA.
Quinn
Colin F
CF
Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
Pilon-Smits
Elizabeth A H
EAH
Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
D000818:Animals; D001181:Arthropods / Q000502:physiology*; D005075:Biological Evolution; D019607:Brassicaceae / Q000378:metabolism* / Q000469:parasitology; D017753:Ecosystem; D007887:Fabaceae / Q000378:metabolism* / Q000469:parasitology; D005247:Feeding Behavior / Q000502:physiology*; D006368:Helianthus / Q000378:metabolism / Q000469:parasitology; D006790:Host-Parasite Interactions / Q000502:physiology*; D012643:Selenium / Q000378:metabolism*
D012643:Selenium