Pollinator diversity and abundance in bitter gourd, Momordica charantia Linn. G. SUBHAKAR 1 , K. SREEDEVI 1 *, K. MANJULA 1 and N. P. ESWARA REDDY 2 1 Department of Entomology, 2 Department of Pathology, S.V Agricultural College, Tirupati-517502, Andhra Pradesh, India *E-mail:kolla.sreedevi@gmail.com ABSTRACT: Field studies were conducted at the Department of Entomology, S.V. Agricultural College, Tirupati, India to document the diversity and abundance of insect pollinators on bitter gourd. Fourteen insect species including 6 hymenopterans, 5 lepidopterans and 3 dipterans were recorded visiting the bitter gourd flowers. Among them, Trigona iridipennis, Halictus gutturosus and Apis florea were the most frequent and abundant visitors. The abundance of T. iridipennis was highest (10.83 bees/m 2 /5 minutes) followed by H. gutturosus (1.06 bees/m 2 /5 minutes) and A. florea (0.37 bees/m 2 /5 minutes). Among all insect visitors, Hymenoptera order constituted the major chunk of pollinators (88.51%) followed by Diptera (5.81%) and Lepidoptera was the least (4.68%). Of total bee population, T. iridipennis had the maximum proportion (77.52%) followed by H. gutturosus (7.60%). Foraging activity was maximum (9.22-8.17 bees/m 2 /5 minutes) at 0900-1000 h of the day. Foraging activity of T. iridipennis, A. florea and H. gutturosus commenced at 0600, 0630 and 0730 h, respectively with peak at 0900-1000 h and ceased by 1400, 1230 and 1300 h, respectively. Keywords: Apis sp. bitter gourd, pollinator diversity, Trigona sp., Halictus sp. INTRODUCTION Insect pollinators play a crucial role in effecting optimum pollination of many crops thus contributing to both increased productivity and quality. Their essentiality is more significant in crops like Cucurbits, which are monecious (male and female flowers are borne at different positions on the same plant). Bitter gourd (Momordica charantia L.) is one of the widely cultivated vegetable crops in Andhra Pradesh. The male to female flower ratio is about 25:1. Long days cause male flowers to bloom up to two weeks before female flowers (Palada and Chang, 2003). Anthesis takes place between 03:30 and 07:30 and stigma remains receptive from 24 h before to 24 h after anthesis and most receptive during early hours of the day (Deshpande et al., 1979). The open position of the bitter gourd flowers makes them easy for the pollinators to access and exploit floral rewards. The high male to female ratio achieves the production of sufficient amount of pollen deposits, thus results in effective pollination. A successfully pollinated flower starts to develop fruit on the second to fifth day after it had opened with petals detached, un-pollinated flowers dry up and the ovary turns to yellow on fifth day (Deyto and Cervancia, 2009). The insects of family Apidae are the most reliable agents for pollination. Among members of Apidae family, honey bees are particularly important pollinators as they are capable of carrying pollen, and in the process, the plants visited by them are benefited (Tewari and Singh, 1983). The conservation and management of insect pollinators is gaining importance day by day for which studies on pollinator  s diversity, species richness and abundance are essential. Hence, the present investigations have been taken up to generate information about the pollinator diversity and abundance in bitter gourd. MATERIALS AND METHODS Field studies were carried out at the Department of Entomology, S.V. Agricultural College, Tirupati from October 2010 to January 2011 to document the diversity and abundance of different insect pollinators of bitter gourd. Sweepings using insect collection nets were made throughout the blooming period at two days intervals during November to January at hourly intervals from morning 0600 to 2000 in the night to collect both diurnal and nocturnal visitors. The collected insects were preserved as dry specimen and got them identified by Dr. C.A. Viraktamath, Emeritus Scientist, Division of Entomology, GKVK, University of Agricultural Sciences, Bangalore. Abundance of different insect visitors/pollinators of bitter gourd crop was studied during their blooming period. The total number of different insect visitors visiting the gourd flowers in a square metre area (approximately 70-90 flowers) was observed for five minutes at hourly interval, using a hand telly counter and stopwatch following the method given by Free (1993). These observations were started when the plants were in 50 per cent bloom. Later, the studies on foraging ecology was limited to major and frequent insect visitors Pest Management in Horticultural Ecosystems, Vol. 17, No. 1 pp 23-27 (2011) 23