Butterflies and their host plants: friendships that flourish the ecosystem

Before taking wing to conquer the skies, butterflies spend their early days as caterpillars, heavily dependent on a narrow set of plants of their choice.

Deep partnerships

Butterflies provide a crucial ecological service in the ecosystem they inhabit.  As adults, they visit a countless number of wildflowers and agriculture crops each year as they seek out nutrient-rich nectar.  In these daily visits, these winged guests also ferry pollen from plant to plant, assisting in those species’ growth and reproduction.

Plants too, in turn, are intricately tied to a butterfly’s lifecycle since their caterpillar days.  Caterpillars are usually herbivorous, and each caterpillar species uniquely relies on a narrow set of plants that evolved with them—their host plants—to provide them with their specific nutritional and chemical requirements. 

This delicate bond between butterflies and their host plants is irreplaceable, and the distribution and abundance of caterpillars is heavily influenced by the distribution and abundance of their host plants—if their hosts disappear, their guests disappear too.

Cataloguing comradery

The butterflies and their host plants in the Western Ghats in India have been documented for over a century.  These existing checklists, however, often suffer from archaic taxonomy, lack specific reference citations, and exclude season- and locality-specific information—particulars essential for further conservation research and action.  A detailed update of the inventory was wanting and, to fix just that, a group of researchers took to the task of systematically collating both previous literature and recent, unpublished records from the hotspot.

Their meticulous work revealed that the region hosts 336 different species of butterflies, of which 12% are endemic.  They also found that records exist for only 320 of those butterfly species and the 834 plant species/groups that they rely on—the host plants of 16 species of butterflies are still unknown.

Floating fates

The new checklist highlights the importance of the diversity, endemism, ecology, and conservation aspects of the butterfly species and their host plants of the Western Ghats.  The critical interdependence of these lever-pullers of the world maintains the fragile balance of their habitats, preventing the entire ecosystem from collapsing due to starvation. 

The complex and tightly interwoven nature of these interactions suggests that the breaking of these connections can be cataclysmic.  With recent sobering researches indicating that insect populations worldwide are plummeting, there is indeed reason to worry and an urgent need to conserve both the hosts and their winged guests in critical ecosystems.

Reference

Nitin, R., V.C. Balakrishnan, P.V. Churi, S. Kalesh, S. Prakash & K. Kunte (2018). Larval host plants of the butterflies of the Western Ghats, India. Journal of Threatened Taxa 10(4): 11495–11550. https://doi.org/10.11609/jott.3104.10.4.11495-11550