Arthropods pest complex and associated natural enemies across different phenological growth stages of ashwagandha (Withania somnifera (L.) Dunal) in India: Insights for developing integrated pest management strategies for sustainable production

Abstract

Withania somnifera (L.) Dunal, commonly known as ashwagandha, is one of the 55 species prioritized by the National Medicinal Plant Board, India. It is pharmacologically, an exceptional medicinal plant used in ayurvedic and indigenous medicinal systems. Damage by insect pests is a crucial obstruction for the industrially and commercially supreme medicinal plant, ashwagandha. Studies on a long-term basis to catalogue different arthropod pests damaging ashwagandha, their peak activity period, the vulnerability of the crop stage, natural enemies associated with recorded insect pests and their activity period were still unexplored. The current study was carried out for three consecutive years and recorded wholly 54 species of arthropods causing injury to the ashwagandha crop across different phenological crop growth stages, and 32 species of natural enemies managing these corresponding insect pests. Of the observed phytophagous arthropods, the Hemipteran species (61 %) were dominant, followed by Coleoptera (13 %), Lepidoptera (9 %), and Orthoptera (9 %). Here we explored the arthropod pest assemblage such as sap suckers (65 %), defoliators (33 %), and root feeders (2 %) infesting ashwagandha in the subtropical region of India. Amongst these pests, Henosepilachna vigintioctopunctata (Coleoptera: Coccinellidae) appeared as a major threat to the quality raw material production of ashwagandha. The full blossom with the initiation of berries was found to be a more vulnerable phenological stage, being attacked by 74 % of recorded arthropod pests. The natural enemies belonging to Coleoptera, Hemiptera, and Hymenoptera outnumbered the leftovers. This study also encapsulates the activity period of arthropod pests and their natural enemies, which can be a path road to choosing other integrable components in management strategy and also to articulate the conservation strategies. Since, information on arthropod pests and their natural enemies in the crop ecosystem is elementary to articulate any Integrated Pest Management (IPM) strategy and to the best of our knowledge, this is the first study conducted for a long period and making an inventory of arthropods infesting the ashwagandha crop, their correspondent natural enemies and their periods of activity can be a roadmap in constructing an IPM strategy for sustainable ashwagandha production.