Chemical defenses of Trifolium glanduliferum against redlegged earth mite Halotydeus destructor.

Trifolium glanduliferum Boiss. was resistant to redlegged earth mite, Halotydeus destructor Tucker (Acari: Penthaleidae), feeding compared with Trifolium subterraneum L. Extracts from T. glanduliferum leaves, obtained with dichloromethane and methanol, acted as feeding deterrents to the redlegged earth mite. Bioassay-directed fractionation of the extracts led to the isolation of several metabolites, coumarin, alpha-and beta-ionone, linalool, medicarpin, that were shown to be deterrent in laboratory experiments. The compounds contributing to the defense of T. glanduliferum were different from those influencing mite feeding on T. subterraneum leaves.