The hymenopterous pollinators of Himalayan foot hills of Pakistan (distributional diversity)
Studies were undertaken to explore the diversity of hymenopterans pollinators from a diverse agroecosystems of Himalayan foot hills comprising the orchards of pome and stone fruits at different altitudes from 2200 to 3000 m from sea level. Field experiments were conducted on seven commercial fruit orchards at five various localities. Out of the total 448 specimens, 60.94% were found in an antemeridian (A.M.) phase and 39.06% specimens were found in post-meridian (P.M.) indicating their activity both diurnal and crepuscular. Rank abundance values revealed that 9 species in 5 genera belonged to four families of order Hymenoptera comprising the diversity of Osmia cornifrons Panzer, Anthophora niveo-cincta (Smith), Anthophora himalayensis Rad., Anthophora crocea Bangham, Bombus tunicatus (Smith), Xylocopa dissimilis Lepel., Xylocopa rufescens Smith, Andrena harrietae Bangham and Andrena anonyma Cam. The calculated values of all diversity indices showed that the lowest diversity was found in a monoculture fruit habitat with well weeded orchards, whereas the diversity of pollinators was found greater in multiple cultures with partially weeded orchards particularly during the successional stage of full bloom in both pomes and stone fruits. A significant difference in the pollinators’ population was seen in the orchards with undisturbed surroundings. The natural ecosystem offers more opportunities of refuges for the insect pollinators compare to those orchards with clean cultivation.
Key words: Diversity, agro-ecosystem, fruit orchards, hymenopterans pollinators, monoculture.