van Swaay, C., Wynhoff, I., Verovnik, R., Wiemers, M., López Munguira, M., Maes, D., Sasic, M., Verstrael, T., Warren, M. & Settele, J.
Lewis, O. (Butterfly RLA) & Cuttelod, A. (IUCN Red List Unit)
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This species has an area of occupancy (AOO) of approximately 350 km² and an extent of occurrence (EOO) of less than 5,000 km² (but larger than 100 km²). The species is extinct on one of the three islands where it used to occur and reported to decline on the others. The number of locations is less than or equal to 5. It is therefore classified as Endangered in the EU27 countries, Europe and the world.
The Canary Islands Large White is restricted to the Canary Islands. This species is widespread and locally common on La Palma. On Tenerife, it is restricted to the northern coastal region. It is probably extinct on Gomera. Its elevational range is 200-1,400 m. This is a European endemic species.
This is a local species, restricted to (semi-) natural areas. Declines in distribution or population size of 6-30% have been reported (data provided by the national partners of Butterfly Conservation Europe).
The Canary Islands Large White occurs in wet and shaded, rocky gullies in laurel forests and wet cliffs. The eggs are deposited on the leaves of Crambe strigosa, a plant species endemic to wet places in laurel forests and on the introduced species Tropaelum majus. The caterpillars live in much the same way as those of the Large White (Pieris brassicae). They are gregarious but disperse in the late larval instars. Detailed habitat descriptions are not available.
Destruction of primary, natural habitat appears to be largely responsible for the decline in many areas and possibly for its extinction on some islands. The habitat is endangered because of anthropogenic pressure (Wiemers, 1995). Like with Pieris wollastoni, the introduction of the alien parasites Cotesia glomerata (Lozan et al. 2007) might be a possible cause of the decline, as the former population of Pieris cheiranthi on La Gomera also became extinct in the 1970s.
More research is needed urgently on the distribution and ecology of the species. Suitable habitats should be protected and appropriately managed. The effects of conservation actions should be monitored by a Butterfly Monitoring Scheme.