DIVERSITY OF INSECT POLLINATORS ON MUSTARD PLANT (Brassica campestris L. 1753) IN ITAHARI, SUNSARI, NEPAL

Abstract

Mustard is winter season oilseed crops of Nepal. Insect pollination increase yield and quality of the fruits. Insect pollinators and flowering plants have mutual relationships. Various insect groups play an important role in pollination of different agricultural, horticultural and medicinal plants. The study was done in Itahari, Sunsari, Nepal to explore the diversity of pollinator insects on mustard plant. Field visit was done in flowering season of mustard in two years (2020-21 and 2021-22). Altogether, Five sampling plots of area 15m2 x15m 2 was selected randomly in each sampling plots. Pollinator insect species was observed from 10.00 am to 3.00 pm in a day time (twice a week) for three months (Nov-Jan) during the period of year 2020-21 and from (Dec-Feb) during the period of year 2021-22 in planting season of mustard.The study was done in three stages of mustard i.e., non-flowering stage, flowering stage and late stage of flowering (about 10% flowering remaining). Different insects were collected from mustard plant by using sweep net as well as hand picking methods. Altogether, 52 insect species were recorded in both years from 7 different orders and 22 different families. Among them, 34 species were pollinators, 5 species were predators and 13 species were pest. During year 2020-21, 43 species were recorded while 38 species were recorded during year 2021-22. Hymenoptera (67%) was most abundant insect order visiting mustard flowers followed by coleoptera (37%), diptera (35%), lepidoptera (31%) and hemiptera (1%). Apis cerana was abundantly found insect species followed by Apis mellifera, Episyrphus bateatus and Anthophora urbana which were observed in both years. Species diversity was higher in year 2020-21 (Shannon index 3.14, evenness index 0.83613) than year 2021-22 (Shannon index 3.07, evenness index 0.84454). Organic products (Ash, cattle’s urine, cattle’s dung) are used for the proper production and productivity of crop yield. Pollinator insects as a part of crop management must be considered by farmers for the higher production and productivity of mustard crop.