Prospect of Managing Invasive Plants by Native Insect Herbivores: A Case Study of Kashmir Himalaya

Abstract Biological invasions are considered a massive threat to native biodiversity engulfing both terrestrial and aquatic ecosystems worldwide while having cascading ecological and economic effects on the invaded regions. Kashmir Himalaya, an important constituent of the biodiversity hotspot, is heavily invaded by invasive alien plants. An inventory of species diversity of invasive plants and native insect herbivores was carried out in different terrestrial habitats of Kashmir Himalaya in the years 2018-19 and 2019-20. The results showed maximum value (3.39) of Shannon’s diversity index at district Kupwara with minimum value (2.967) at district Srinagar. Margalef Index attained maximum value (5.966) at district Bandipora and a minimum value (4.724) at district Srinagar. Our data revealed maximum value of evenness (0.732) in district Baramulla with minimum value (0.650) at district Pulwama. Similarly, district Baramulla of North Kashmir showed highest Simpson value (0.957) while district Srinagar with minimum value (0.934). Plantago major belonging to the family Plantaginaceae was found to be the most dominant invasive plant species followed by Taraxacum officinale of family Asteraceae. Altica himensis was the most abundant native insect herbivore feeding on almost all invasive plant species with maximum damage on Rumex hastatus of Polygonaceae family. A total of 42 invasive plant species were recorded during the entire study period, of which 12 are worst invaders namely Plantago major, Taraxacum officinale, Trifolium rapens, Trifolium pratense, Plantago lanceolata, Cyanodon dactylon, Anthemis cotula, Clinopodium umbrosum, Ranunculus arvensis, Veronica persica, Dactylis glomerata and Vulpia myuros. A total of 14 native insect herbivores species were identified on these invasive alien plants, of which the prospect of 06 insect herbivore species as potential biocontrol agents is promising. Among the collected insect herbivores, a few namely Chrysolina herbacea, Melanoplus differentialis, Pieris brassicae and Altica himensis are being reared on native and invasive plant species under laboratory conditions. Preliminary results of these native insect herbivors as potential biocontrol agents against invasive alien plants are encouraging. These novel, non-coevolved insect herbivores can not only be exploited to control the spread of invasive plants but could also thwart huge economic losses associated with the management of invasive plants worldwide.