Studies on diversity and abundance of parasitoids of Chromatomyia horticola (Goureau) (Agromyzidae: Diptera) in north-western Himalayas, India

Abstract

Pea leafminer, Chromatomyia horticola (Goureau) is an important pest of many vegetable and ornamental crops. The present investigation was carried out to study the parasitoid diversity of this pest in different agroclimatic conditions of Himachal Pradesh, India. Sixteen species of parasitoids viz. Diglyphus horticola Khan, Diglyphus isaea (Walker), Zagrammosoma sp., Pnigalio sp., Quadrastichus plaquoi Reina and LaSalle, Asecodes erxias (Walker), Closterocerus sp., Neochrysocharis formosa (Westwood), Chrysocharis sp, Chrysocharis indicus Khan, Pediobius indicus Khan (Eulophidae), Opius exiguus (Wesmael), Dacnusa sp. (Braconidae), Cyrtogaster sp., Sphegigaster sp. (Pteromalidae), and Gronotoma sp. (Figitidae) were recorded parasitizing C. horticola in different agro-climatic zones of Himachal Pradesh. Agro-climatic zone II (sub-temperate mid-hills) was the richest in parasitoid diversity (14 species) followed by zone I (11 species), zone III (7 species) and zone IV (4 species) which are characterized by sub-tropical sub-montane, wet temperate high hills and dry temperate high hills, respectively. Shannon diversity index, species richness, species evenness and species dominance varied from 0.69-1.71, 1.39-2.64, 0.50-0.71 and 0.29-0.50, respectively. D. isaea and D. horticola were the dominant parasitoids of C. horticola contributing 41.46-80.15 and 9.16-50.65 per cent of the total parasitization, respectively, in different agro climatic zones. The study highlights the role of different parasitoids in natural control of the leaf miner and will be useful for designing the IPM strategies for the pest.