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Chromolaena odorata
A serious invasive weed that is preferred by Butterflies for Nectar
What better joy than butterflies nectaring on myriad of colour flowers. Butterflies need nutrients and sugars besides other minerals for their survival and reproduction. For the sugars, they are greatly dependant on the nectaring plants. Nectar is a sugar-rich liquid produced by plants in glands called nectaries, either within the flowers with which it attracts pollinating animals such as bees, butterflies, wasps, birds, etc. Nectar secretion increases as the flower is visited by pollinators. After pollination, the nectar is frequently reabsorbed into the plant. Butterflies prefer the native plants for their nectars generally; however, we find them equally and in fact preferably seek the nectar of a few serious weed plants such as Chromolaena odorata and Lantana camera. Chromolaena odorata is a tropical and subtropical species of flowering shrub in the sunflower family( Asteraceae). It is native to the North and South American continents. It has subsequently been introduced to tropical Asia, west Africa, and parts of Australia, either accidentally or intentionally. Common names include Siam weed, Christmas bush, devil weed, camphor grass, common floss flower, communist green, triffid and Communist pacha. It was earlier taxonomically classified under the genus Eupatorium but is now considered more closely related to other genera in the tribe Eupatorieae. Chromolaena odorata is considered an invasive weed of field crops and natural environments in its introduced range. It has been reported to be the most problematic invasive species within protected rainforests in Africa. In Western Africa it prevents regeneration of tree species in areas of shifting cultivation. It affects species diversity in southern Africa. The plant ' s flammability affects forest edges. In Sri Lanka it is a major weed in disturbed areas and coconut plantations. A study in India reveals that sites with high biotic pressure, maximum temperature variation, open forest canopy, and free from herbivory are the most suitable habitat for the growth of C. odorata. Australian government has drawn an elaborate plan to eradicate this weed( it is called Siam Weed in Australia). In Tamil Nadu, the weed can be seen on the mountains and places near to it and is feared to be slowly expanding due to its effective short and long-distance dispersal. The plant may be preferred as ornamental garden plant helping further its expansion and stability. We were able to observe in single location the presence of this weed for a period of about 2 years( in the plains and not in hills / foothills). Whenever the plant was in full bloom, it was preferred by butterflies from all families, with an exception of Swallowtails( Papilionidae) showing a lesser preference. The butterflies tend to get attached to their favourite spot for long time unless the general method of moving over flowers in a short span. Only the Swallowtails, like Tailed Jay, show the tendency of swiftly moving between flowers. While we are not clearly aware of the status of this weed in the state of Tamil nadu and its impact on eco-system and any eradication plan for them at the moment, what is clearly emerging is that this weed has become an importance source of food for not only butterflies, but for moth, bees and wasps too.
Reference:
1. https:// www. cabi. org / isc / datasheet / 23248 2. https:// en. wikipedia. org / wiki / Chromolaena _ odorata 3. https:// en. wikipedia. org / wiki / Nectar 4. Gautam Mandal and Shambhu Prasad Joshi. Invasion establishment and habitat suitability of Chromolaena odorata( L.) King and Robinson over time and space in the western Himalayan forests of India. Journal of Asia Pacific biodiversity 7( 2014) 391- 400.
5. Weed management Guide. Siam weed or Chromolaena. The CRC for Australian Weed Management and the Common wealth Department of the Environment and Heritage.
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