An investigation of the Consejo Superior de Investigaciones Científicas (CSIC), in collaboration with the Max Planck Institute for Chemical Ecology, has discovered a few chemical compounds on the surface of the leaves of the herb of Santa Barbara, the yielding, that attract moth cruciferousalso called Cabbage Moth, and stimulate their release of eggs.

The herb of Santa Barbara, Barbarea vulgaris, also is known for maintaining a "surprising" relationship with the moth of cabbage, Plutella xylostella. This plant of the cruciferous family, to which also belong the broccoli and cauliflower, is very attractive for the moth and stimulus to deposit their eggs on it. However, the larvae of the cabbage butterfly fail to develop because the leaves of the herb of Santa Barbara contains saponins fagorrepulsivas, causing his death by starvation.

"Was I knew that the yielding alone attract and stimulate the implementation of eggs in the cabbage moth, but previous studies on the presence of these substances on the leaf surface of the cruciferous had given rise to conflicting results", explains researcher Francisco Rubén Badenes, Institute of agricultural sciences of the CSIC. This research shows that these chemical compounds are present in the surface leaf of the Santa Barbara grasses and other plants of the genus Barbarea, but not in other cruciferous species being investigated.

The relationship between the moth and the grass of Santa Barbara, which could be termed antievolutiva, could have a practical application: use the plant as a trap crop that can kill entire crops of cabbage or broccoli to prevent this insect pests,, among other cruciferous species. "The plant still not has been used at commercial level with this function." "However, experiments conducted so far indicate a great potential as a crop trap for the control of the moth of cruciferous, especially in cases where may not be used insecticides to control," explains Badenes.

"The study also shows that saponins fagorrepulsivas are present only in the interior of the leaves of plant, not on its surface." In this way, the moth of cruciferous cannot detect them and lays her eggs on the grass of Santa Barbara. "But the larvae do not come to develop, since the flavor of the leaves is so unpleasant for them, which stop eating and they end up dying from starvation", adds the researcher at the CSIC.

To analyze the substances involved in the relationship between the grass of Santa Barbara and cruciferous moth, the researcher applied Gum Arabic diluted in water on the leaf of the plant. The properties of the gum Arabic allow that dries, you can rid of the plant without damaging the tissue of the leaf, just as if you took off an adhesive. This technique manages to isolate the wax on the surface of the leaves and helped to locate and quantify for the first time the yielding in this area of the plant.