Biological activity of natural phytoecdysteroids from Ajuga iva against the sweetpotato whitefly Bemisia tabaci and the persea mite Oligonychus perseae.

BACKGROUND

Ecdysteroids are steroid hormones that control moulting and govern several changes during metamorphoses in arthropods. The discovery of the same molecules (phytoecdysteroids) in several plant species displayed a wide array of rather beneficial agricultural impact. Many representatives of the genus Ajuga plants contain phytoecdysteroids with a 5β-7-ene-6-one system exhibiting physiological activities in insects.

RESULTS

By means of chromatographic (silica gel column, TLC) and LC-MS, two major ecdysteroids (20-hydroxyecdysone and cyasterone) have been isolated and identified from Israeli carpet bugle Ajuga iva (L.) Schreber (Lamiales: Lamiaceae) plants. Ajuga iva extract fractionated on the silica gel column yielded two fractions that showed high activity against the sweetpotato whitefly Bemisis tabaci and the persea mite Oligonychus perseae. A dose of 5 mg AI L(-1) of the purely identified A. iva ecdysterone significantly reduced fecundity, fertility and survival of these pests, while commercial 20-hydroxyecdysone at the same dose had lesser effects.

CONCLUSIONS

The results demonstrate considerable efficacy of natural phytoecdysteroids against major agricultural pests, and suggests that these materials should be considered for potential development of friendly control agents.