The highly invasive Siam Weed, Chromolaena odorata (L.) King and Robinson (Asteraceae), as a seasonal prime nectar source for butterflies (Lepidoptera: Papilionoidea) and other insects (Insecta: Lepidoptera, Hymenoptera, Coleoptera) in West Africa

Abstract

During mass-blooming in the dry season, the highly invasive Siam Weed, Chromolaena odorata, appears to be a prime nectar source for butterflies and a range of diurnal moths and other insects in West Africa. About 10 % of the West African butterfly fauna were recorded visiting C. odorata flowers between Sierra Leone and Western Cameroon as a result of opportunistic observations between 2010 and 2021. Predators on flower-visiting insects, such as crab-spiders and Flower Mantises, also seem to have become adapted to the newly available food-source. These records indicate that beyond the well-known adverse effects of C. odorata invasion to regeneration of natural vegetation on disturbed ground and the exposure of natural rainforest habitats to wildfires because of the plant’s susceptibility to fire, the diet shift of a considerable proportion of pollinators could imply further threats to biodiversity, such as reducing the reproductive rate of forest plants pollinated by butterflies. Specific studies further targeting the subject are urgently needed.