Annual Symposium o f the D epartm ent o f Agriculture, Sri Lanka. 2:325-343 Septem ber 2000 NATIVE BEES (HYMENOPTERA: APOIDEA: APIFORMIS) OF SRI LANKA AND THEIR IMPORTANCE IN AGRICULTURE AND BIODIVERSITY A N U R A W IJE S E K A R A H orticu ltu ral C rops R esearch and D evelopm en t Institu te P.O . B ox 11, P eraden iya ABSTRACT A taxonomic review of the bees (Apoidea: Apiformis) o f Sri Lanka was carried out along with an observational study on bee pollinators o f cucum ber. Five fam ilies, Anthophoridae, Apidae, Colletidae, Halictidae and M egachilidae are represented by 49, 4, 3, 52, and 24 species respectively. A list o f 132 bee species known to occur in Sri Lanka is given with short general descriptions of the fam ilies and family groups they belong to. From an observational study it was found out that there was no fruit set in cucum ber variety LY 58 when insects were prevented from visiting flowers. Ten species o f bees visited cucum ber flowers o f which Apis cerana, Ceratina sp., and Pithitis sp. were the most frequent. The possible im pact o f native bees on agriculture production and biodiversity is discussed. Lack of or inadequate pollination o f crops may reduce the crop yields and quality o f produce. The decline of native bees due to human activity may adversely e ffec t biodiversity. K E Y W O R D S: Agriculture, Apoidea, Biodiversity, Hym enoptera, Pollination, Sri Lanka. INTRODUCTION Bees are a group o f about 20,000 species o f insects in the order Hymenoptera distributed throughout the world (Michener, 1993). They are closely related to wasps but differ from them by being phytophagous in both larval and adult stages. Some have evolved to be highly social (eusocial) like the honey bees but many others are solitary (Roubik, 1989). Except for the honey bee, A p is c e ra n a , other bees o f Sri Lanka have not been well studied either systematically or biologically. Much o f the information derived from considerable amounts o f research on honey bees o f Sri Lanka can be found in Punchihewa (1994), but no comparable treatments exist for other bees. The Catalogue o f Hymenoptera (Dalla Torre, 1896) listed 17 bee species from Sri Lanka and Bingham (1897) reproduced the descriptions o f 47 species. Since then more species o f bees from Sri Lanka have been recorded and described by many authors but, this information is scattered in the vast taxonomic literature. Although bees are a very important group that is required to be studied in relation to agriculture and biodiversity no attempt has been made in Sri Lanka to study them up to now. The importance o f bees for agriculture and biodiversity rests on the fact that they have evolved to be specialized pollinators of many plant species. Their habit o f mass or progressive provisioning o f larvae with pollen and nectar as food has led to the evolution of close interdependence between bees and flowering plants (angiosperms). Although most o f the world’s food supply comes from wind pollinated or self pollinated crops, the value o f insect pollinated crops is substantial 3 2 6 W1JESEKARA (McGregor, 1976). Many fruit and vegetable crops are dependent on insects for pollination or benefit by flower visiting insects of which bees are the most prominent group. Pollination not only affects the crop yield but also affects the quality of the produce. The lack of pollination would reduce the fruit set and inadequate pollination would lead to a higher percentage of inferior fruits and sterile seeds (Kearns and Inouye, 1997). Therefore presence of bees and other pollinators in adequate numbers is necessary for optimal agricultural production. Not so obvious as the relevance to crop production is the bees' role in maintaining biodiversity. Recent attention on decreasing biodiversity in many areas of the world has induced the study of the role of bees on maintaining biodiversity (Neff and Simpson, 1993; O 'Toole, 1993). Both in agriculture production and maintaining biodiversity, it is not only the presence of bees that is important but also presence in sufficient numbers. The study was initiated in 1998 on pollination of cucurbitaceous crops in Sri Lanka. This study has compiled a list o f bees known to occur in Sri Lanka and has made some observations on cucumber pollination and bees visiting cucumber flowers. MATERIALS AND METHODS Taxonomic literature was surveyed (upto December 1999) for bees described or recorded from Sri Lanka. The bee species known to occur in the country were noted and the taxonomic history for each species was reviewed to determine the currently valid scientific names. Bees visiting cucumber flowers were collected in an observational study carried out during the seasons 1998 yala (May-September), 1998/99 maha (November-March) and 1999 yala at the research fields o f Horticultural Crops Research and Development Institute, Gannoruwa. Commonly cultivated cucumber variety LY 58 was planted according to the Department o f Agriculture recommendations, in 12, 4X3 m plots. To study the effect of insect pollinators the same variety was planted in a net house at the In Service Training Institute, Gannoruwa, which effectively excludes all flower visiting insects. Although the cucumber vines in the field were not provided with trellises, the net house crop was allowed on triangular trellises 1.5 m high, for easier management. From the net house cultivated plants, few randomly selected female flowers were hand pollinated to ascertain that the abiotic net house environment does not affect fruit set of the cucumber variety. BEES IN AGRICULTURE AND BIODIVERSITY 3 2 7 RESULTS AND DISCUSSION Bees are grouped in the superfamily Apoidea which also includes sphecoid wasps. Michener (1993) divided bees into eleven families. Five of the families, Anthophoridae, Apidae, Colletidae, Halictidae and Megachilidae, are represented in Sri Lanka. While Apidae includes all the eusocial bees, the other families consist mostly of solitary and parasocial bees. Little is known about the biology of most o f the native bees o f Sri Lanka. Some relevant biological information and a key useful for identification of genera can be found in Batra (1977). List of bees in Sri L anka In the following section bees known to occur in Sri Lanka are listed under their respective families. A short general introduction to each family, based mainly on O 'Toole and Raw (1991) is followed by the currently valid species Jiames in bold letters and a recent reference to the valid name. Collection localities, when found in literature, and any junior synonyms relevant to Sri Lanka are indicated under each specific name. Anthophoridae Anthophoridae is a large family with thousands of species distributed world wide. Many are large bee as common carpenter bees in Sri Lanka. Anthophoridae is divided into three subfamilies, Anthophorinae, Nomadinae and Xylocopinae. Anthophorinae In Anthophorinae most species nest in the ground and few excavate dead wood. It is represented in Sri Lanka by Amegilla (Tribe: Anthophorini), Tetralonia, Thygatina (Eucerini), and Thyreus (Melectini). Anthophorini Amegilla (Zonamegilla) cingulata (Fabricius): Brooks 1988: 511 Amegilla (Zonamegilla) cingulifera (Cockerel)*: Brooks 1988:511; Colombo, Kalutara, Ratnapura. Amegilla (Zonamegilla) com beri (Cockerel)*: Brooks 1988: 511; Galie, Hambantota, Mannar, Matara, Monaragale, Puttalama, Ratnapura. * From specimens in Smithsonian collection identified by M.A. Lieftnick (1987) Amegilla (Zebram egilla) fallax (Smith); Brooks 1988: 504; Mahailluppalama (MI), Haputale, Seenigoda. Amegilla (Glossamegilla) insislaris (Smith): Brooks 1988: 513 3 2 8 WIJESEKARA Amegilla (Amegilla) quadrifasciata (de Villers): Brooks 1988: 450 Amegilla (Zonamegilla) puttalama (Strand): Brooks 1988: 511; Bandarawela, Negambo. Amegilla (Zonamegilla) subinsularis (Strand)*: Brooks 1988: 513; Galle, Kalutara, Rantnapura. * From specimens in Smithsonian collection identified by M.A. Lieftnick (1987). Amegilla (Zebramegilla) subcoerulea (Lepeletier): Brooks 1988: 504; Kalutara Amegilla (Glossamegilla) violacea (Lepeletier): Brooks 1988: 513; Ml, Seenigoda. Amegilla (Zonamegilla) zonata (Linnaeus): Brooks 1988: 511; Bandarawela, Haputale, Ml, Negambo, Puttalama, Seenigoda. Tetralonia commixtana Strand 1913: 146; Nuwara-Eliya, Tetralonia taprobanicola Strand 1913: 147; Kantale Thygatina fumida Cockerell 191 lb: 237; Kandy All species in Melectini do not make nests and lay their eggs in nests of other anthophorine bees (such bees are called Cuckoo Bees) Thyreus ceylonicus ceylonicus (Friese): Lieftinck 1962: 134; Anuradhapura, Deiyannewela, Hantana, Haragama, Kandy, Kantale, Kuchchaveli, Mihintale, Nalanda, Nugawela, Peradeniya, Puttalama, Teldeniya, Trincomalee, Weligama. Thyreus histrio (Fabricius): Lieftinck 1962: 11; Awissawella, Dambulla, Kandy, Negambo, Tissa, Peradeniya, Trincomalee. =Crocisa rectangula Meyer: Lieftinck 1959: 25, 34 Thyreus insignis (Meyer): Lieftinck 1962: 109; Kandy, Walawela. Thyreus ramosellus (Cockerell)*: Lieftinck 1962: 17; Puttalama, Trincomalee. * From specimens in Smithsonian collection identified by M.A. Lieftnick 1987. Thyreus takaonis (Cockerell): Lieftinck 1962: 21; Awissawella, Balakaduwa, Dambulla, Kalpitiya, Mannar, Matale, Mihintale, Nalanda, Negambo, Paradna, Puttalama, Seenigoda, Tissa, Uragalla, Weligama. =Crocisa ramosa var reepeni Friese 1918: 496 Thyreus surniculus Lieftinck: Lieftinck 1962: 27; Inginiyagala, Mannar, Passara, Tambuttegama, Tissamaharama. Nomadinae Nomadinae is represented by Nomcida in the tribe Nomadini. All species of Nomadinae are Cuckoo bees. N om ada adusta Smith: Alexander & Schwarz 1994: 256 N om ada an tenoata Meade-Waldo: Alexander & Schwarz 1994: 256; Kandy. BEES IN AGRICULTURE AND BIODIVERSITY 3 2 9 Nomada bicellula Schwarz: Alexander & Schwarz 1994: 256 Nomada ceylonica Cameron: Alexander & Schwarz 1994: 256 Nomada lusca Smith: Alexander & Schwarz 1994: 257 Nomada priscilla Nurse: Alexander & Schwarz 1994: 257 Nomada wickwari Meade-Waldo: Alexander & Schwarz 1994: 257; Colombo Xylocopinae Xylocopinae are known as carpenter bees due to their habit of excavating nests in solid wood or pith of plant stems. This subfamily is represented by Braunsapis (Allodapini), Ceratina, Pithitus (Ceratinini) and Xylacopg. (Xylacopini). Tribe Allodapini include subsocial or primitively eusocial bees that nest in pithy stems or twigs. Four species are known from Sri Lanka. Braunsapis cupulifera (Vachal): Reyes 1991: 197 Braunsapis flaviventris Reyes 1991: 194 Braunsapis mixta (Smith): Reyes 1991: 187; Colombo, Gampaha, Hiniduma, Medirigiriya, Nalanda, Puttalama, Yakkala. =Prosopis leucotarsis Cameron 1897: 363 =Allodape marginata:Smith: Strand 1913: 145 Braunsapis picitarsis (Cameron): Reyes 1991: 189; Kollupitiya, Medirigiriya, Sigiriya, Yakkala. i The smaller carpenter bees are in the tribe Ceratinini. They usually nests in pithy stems and are common. While Ceratina can either be solitary or primitively social all known Pithitis species are solitary. Ceratina (Xanthoceratina) beata Camaron: Vecht 1952: 48; Trincomalee Ceratina (Ceratinidia) hieroglyphica Smith: Michener 1965: 221; Dambulla, Nalanda, Weligama. Ceratina (Xanthoceratina) picta Smith: Hirashima 1971: 356 Pithitis (Pithitis) binghami (Cockerell): Hirashima 1969: 658 Pithitis (Pithitis) smaragdula (Fabricius): Hirashima 1969: 661; Bentota, Kantale, Sigiriya. Large carpenter bees are grouped in the tribe Xylocopini. They are probably the most familiar group of bees other than honey bees. M ost of them are solitary and excavate their nests in hard wood. Xylacopa tranquebarica is known to be nocturnal (Batra, 1977). Xylocopa (Biluna) auripennis Lepeletier: Hurd & Moure 1963: 297; Habarana Xyiocopa (Biluna) nasalis Westwood: Hurd & Moure 1963: 310 3 3 0 W1JESEKARA =Xylocopa dissimilis Lepeletier: Bingham 1897: 538 Xylocopa (Ctenoxylocopa) fenestrata (Fabricius): Tkalcu 1973: 63; Aluthnuwara, Balangoda, Hambantota, Nalanda, Paradna, Seenigoda, Talawa. Xylocopa (Koptortosoma) aestuans (Linnaus): Hurd & Moure 1963: 296 Xylocopa (Koptortosoma) bryorum Fabricius: Hurd & Moure 1963: 299 Xylocopa (Koptortosoma) confusa Perez: Hurd & Moure 1963: 301; Anuradhapura, Nalanda. Xylocopa (Koptortosoma) ruficornis Fabricius: Hurd & Moure 1963: 314; Bandarawela , MI, Tharakundu (NW Mannar) =Xylocopa ceylonica Cameron 1901: 32 =Xylocopa clavicrus Maidl: Strand 1913: 146 =Xylocopa verticalis Lepeletier: Friese 1918: 495 =Mesotrichia (Koptortosoma) ruficornis Fabricius: Tkalcu 1973: 63 Xylocopa (Nodula) amethystina (Fabricius): Hurd & Moure 1963: 297; M I, M atale Xylocopa (Platynopoda) tenuiscapa Westwood: Hurd & Moure 1963: 317; Balangoda, Colpetty, Galle, Hambantota, Hikkaduwa, Inginiyagala, Kuchchaveli, Labugama, Ratmalana, Trincomalee, Wellawaya. =Xylocopa albofasciata Sichel: Bingham 1897: 542 =Mesotrichia (Platynopoda) tenuiscapa Westwood: Tkalcu 1973: 63 Xylocopa(Nyctomelitta) tranquibarica (Fabricius): Hurd & Moure 1963: 317; Kantale Xylocopa (Zonohirsuta) bhowara Maa: Hurd & Moure 1963: 298 Xylocopa (Zonohirsuta) dejeanii Lepeletier: Hurd & Moure 1963: 302; Anuradhapura, Colombo. =Xylocopa collaris Lepeletier: Bingham 1897: 543 Xylocopa (Zonohirsuta) nigrocaerula Smith: Hurd & Moure 1963: 311 Apidae Apidae include all the eusocial bees and it is divided into four subfamilies. Except Bombinae, which consist o f bumble bees and euglossinae, the orchid bees, the other two subfamilies are represented in the country. Apinae There are three species o f honey bees in Sri Lanka. Apis do rsa ta Fabricius: Michener 1990: 141; Nalanda Apis fflorea Fabricius: Michener 1990: 141; Kandy, Matale, Nalanda, Negambo, Pankulam, Paradna, Puttalama, Weligama Apis cerana Fabricius: Ruttner 1988:120; Haputale, Seenigoda. =Apis indica Fabricius: Bingham 1897: 558 BEES IN AGRICULTURE AND BIODIVERSITY 3 3 1 Meliponinae Meliponinae consist of stingless bees, which are distributed in the tropics world over. Sri Lanka has a single species which nests in places like hollow logs, tree trunks etc. Trigona (Heterotrigona) iridipennis Smith: Sakagami 1978: 216; Colombo, Elephant-Pass, Hambantota, Kottawa, Lahugala, Labugama, Nalanda, Palatupana, Sigiriya, Sinharaja, Ukgaltota, Wellawaya, Trincomalee. =Trigona prazterita Walkerl860: 305 Colletidae Colletidae consists of over 2000 species in the world and divided into five subfamilies (Michener, 1993). The Sri Lankan species belongs to Hylaeinae, members of which are distributed worldwide. The females of colletids^line their brood cells with a transparent water proof membrane resistant to fungal attack. Hylaeine bees are relatively hairless and lack pollen scopa. Females transport pollen in their crops. Many species nest in plant stems, plant galls, beetle borings, old cells of bees and wasps and some nest in the ground. Hylaeus (Paraprosopis) krombeini Snelling 1980: 3; Hunuvilgama (Wilpattu) Hyleaus (Prosopis) monilicornis (Motschulski): Snelling 1980: 1 Hylaeus sedens Snelling 1980: 13; Kandy Halictidae This family of bees has over 5000 species described worldwide. M any halictids are metallic in coloration and includes solitary as well as primitively eusocial bees. All three subfamilies, Rophitinae, Halictinae and Nomiinae are represented in Sri Lanka. Most halictids escavate nests in the ground and line their brood cells with a mixture of chemicals, which is not transparent as in colletids. Rophitinae Rophitinae is represented by Systropha. Systropha tropicalis Cockerell: Baker 1996: 1535; Kandy, Matale, Seenigoda. ^Systropha butteli Friese, 1913: 87 3 3 2 WIJESE KLARA Halictinae Halictinae are called sweat bees due to their attraction to human perspiration. Thay are represented by Halictus, Homalictus, Lasioglossum , Pachyhalictus (Halictini) and Ceylatictus (Nomiodini). Halictus ciris Cameron: Bluthgen 1926: 537; Kandy, Matale, Nigambo. Halictus ducalis Bingham: Bingham 1897: 435 Halictus paradnanus Strand: Bluthgen 1926: 456; Colombo, Paradna (probably Peradeniya). Halictus taprabonae Cameron: Bingham 1897: 428 Halictus timidus Smith: Bingham 1897: 429 Halictus trincomalicus Cameron: Bluthgen 1926: 608; Trincomalee Halictus (Seladonia) lucidipennis Smith: Sakagami & Ebmer 1987: 321; Angunakolapelessa, Colombo, Ella, Hasalaka, Hunuvilgama, Kandy, Kokmotte, Labugama, Lahugala, , Padaviya, Palatupana, Parayanakulam, Pimburathewa, Ratmalana , Teldeniya, Trincomalee, Udawalawa. =Halictus vernalis Smith: Ebmer 1980: 181 Homalictus singhalensis (Bluthgen): M ichener 1965: 181 Lasioglossum (Ctenonomia) clarum (Nurse): Sakagami 1990*: Anuradhapura, Hambantota, Mannar, Monaragala, Pollonnaruwa, Trincomalee. Lasioglossum (Ctenonomia) vagans (Smith): Sakagami 1990*: Badulla, Colombo, Galle, Kandy, Matale. =Halictus schmiedeknechti'. Friese 1918: 493 =Hcilictus nalandicus Strand 1913: 140 =Halictus centrophorus Strand 1913: 140 *From specimens in Smithsonian collection identified by Sakagami (1990). Lasioglossum (Lasioglossum) albescens Smith: Michener 1965: 173; MI, Nalanda, Trincomalee. =Hlictus javanicus: Friese 1918: 493 =Halictus amblypygusStrand 1913: 141 Lasioglossum (Lasioglossum) semisculptum (Cockerel): Michener 1965: 173; Kalutara. Lasioglossum (Lasioglossum) tamulicum (Bluthgen): M ichener 1965: 173 Lasioglossum (Nesohalictus) halictoides (Smith): Sakagami 1991: 169; Anuradhapura. =HaIictus ceylonicus Strand 1909: 187 =Halictus strandiellus Cockerell 191 la: 192 =Halictus hornianus Strandl913: 138 Lasioglossum (N esohalictus) serenum (Cameron): Sakagami 1991: 169; Colombo, Angunakolapelessa. Lasioglossum (Sudifla) a lp h eu u m (Cameron): Sakagami, Ebmer and Tadauchi 1996: 164; Haputale, Kandy, Nuwara-Eliya. BEES IN AGRICULTURE AND BIODIVERSITY 3 3 3 „ =Hal tic us ceylon icus Cameron 1902: 254 =Ceylonicolasubmicans Friese 1918: 504 Lasioglossum (Sudila) aulacophorum (Strand): Sakagami, Ebmer and Tadauchi 1996: 154: Hatton. Lasioglossum (Sudila) bidentatum (Cameron); Sakagami, Ebmer and Tadauchi 1996: 175: Hakgala, Kande-Ela Reservoir, Nuwara-Eliya, Ohiya, Pidurutalagala, Worlds End. =Sadila ceylonica Cameron 1898: 55 =Ceylonicola atra Friese 1918: 502 =CeylonicoIa rebrivenrris Friese 1918: 503 Lasioglossum (Sudila) kandiense (Cockerell): Sakagami, Ebmer and Tadauchi 1996: 160; Kandy, Kanneliya, Kitulgala, Sinharaja. Pachyhalictus (Pachyhalictus) bedanus (Bluthgen): Michener 1978: 517; Peradeniya. Pachyhalictus (Pachyhalictus) kalutarae (Cockrel): Michener 1978: 518; Kalutara, Peradeniya, Pundalu-Oya. =Halictus amplicollis Friese 1918: 500 Pachyhalictus (Pachyhalictus) sigiriellus (Cockerell): Michener 1978: 518: Kalutara. Pachyhalictus (Pachyhalictus) vinctus (Walker): Michener 1978: 518 Nomiodini Nomiodini are minute bees with abundant yellow to white markings on the body. Ceylalictus cereus (Nurse): Pesenko 1983: 108: Colombo. —Ceratina divisa Cameron 1907: 1003 Ceylalictus horni (Strand): Pesenko 1983: 108: Matale. Ceylalictus taprobanae (Camaron): Pesenko 1983: 108 Nomiinae Nomiinae are mostly solitary bees. They are represented in Sri Lanka by Nomia and Steganomus. Nomia biroi Friese: Seenigoda: Friese 1918: 507; Polgahawela, Ragama. Nomia butteli Friese: Friese 1918: 505: Seenigoda. Nomia capitata Smith: Bingham 1897: 455 Nomia carinata Smith: Bingham 1897: 453 Nomia ceylonica Friese: Friese 1918: 506: Seenigoda. Nomia crassiuscula Friese: Friese 1918: 504: MI. Nomia elegantula Friese: Friese: 1918: 505; Seenigoda. Nomia exagens (Walker) Cockerell 191 lb: 218 3 3 4 WIJESEKARA Nomia m atalea Strand 1913: 144; Matale, Negambo, Paradna. Nomia oxybeloides Smith: Strand 1913: 145: Negambo, Sigiriya. Nomia pu tta lam a Strand 1913: 143; Horrowpatana, Puttalama. Nomia rufa Friese: 1918: 508: Peradeniya. Nomia rustica Westwood: Bingham 1897: 457 Nomia (A ustronom ia) austelia Hirashima 1978: 92; Palatupana (Hambantota) Nomia (A ustronom ia) krom beini Hirashima 1978: 98: Colombo, Hambantota, Hunuwilgama, (and various other locations). Nomia (Austronom ia) notiom orpha Hirashima 1978: 100; Ekgal-Aru, Hambantota, Hasalaka, Kandy, Mahiyangana, Parayanakulam, (and various other locations) Nomia (A ustronom ia) ustuia Cockerell: Hirashima 1978: 96; Anuradhapura, Dambulla, Labugama, Gilimale, Kandy, Manampitiy, Padaviya, Pimburattawa, Puttalama, Ratnapura, Wilpattu Nomia (Hoplonom ia) striga ta (Fabricius): Michner 1965: 156; Puttalama. Nomia (Hoplonom ia) westwoodi Gribodo: Michener 1965: 156; Negambo. N orm ia (Nomia) curvipes (Fabricius): Michener 1965: 154 Nom ia (Rhopalom elissa) aurifrons Smith: Michener 1965: 159; Negambo. Nom ia (Rhopalom elissa) basipicta Wickwar: Michener 1965: 159: Nom ia (Rhopalom elissa) carinicollis Cameron: Michener 1965: 159 Nomia (Rhopalom elissa) com beri Cockerell: Michener 1965: 159; Kalutara. Steganoraus nodicornis Smith: Strand 1913: 142: Negambo, Matale Megachilidae A large family of bees with thousands of species distributed worldwide. O f .the two subfamilies only Megachilinae is found in Sri Lanka. Three tribes are represented. Megachilinae Megachilinae are commonly called leaf-cutter and mason bees. M ajority o f the species make nests in existing cavities in wood. Most line their cell walls or partition the cells with material collected by the females. The kinds of material varies according to the species and include leaves, petals, chewed leaves or petals, plant or animal hairs, plant resins or mud and pebbles. Megachilinae is represented by Lithurgus (Lithurgini), Anthidiellum, Euaspis, Exanthidium, (Anthidini) and Coelioxys, Liothyrapis, Megachile (Megachilini). Lithurgini are solitary bees, known to excavate their nests in timber and they do not line their cells. BEES IN AGRICULTURE AND BIODIVERSITY 3 3 5 Xithurgus (Lithurgus) atratus Smith: Michener 1965: 185 Anthidiini Anthidiellum (Pycnanthidium) ramakrishnae (Cockerell): Pasteels 1972: 98; Passara Euaspis (Parevaspis) edentata Baker: Baker 1995: 283; Kandy, Matale, Minneriya, Pollebedda. —Euaspis (Parevaspis) carbonaria (Smith): Pasteels 1980: 82, Exanthidium rotundiventre Pasteels 1987: 234 Liothyrapis apicata Smith: Pasteels 1987: 233; Padaviya Megachilini Coeloxys confusus Smith: Pasteels 1987: 225; Palatupana, Trincomalee. Coelioxys fenestrata Smith*; Kandy, Trincomalee. Coelioxys fuscipennis Smith*; Hambantota. Coelioxys intacta Friese*; Ampara. * From specimens at Smithsonian collection identified by J. Pasteels (1997). Coeloxys nitidoscutellaris Pasteels 1987: 228; Palatupana Coeloxys (Allocoelioxys) angulata Smith: Pasteels 1987: 229; Wilpattu, Trincomalee. Coeloxys (Allocoelioxys) capitata Smith: Pasteels 1987: 230; Angunakolapellessa, Kandy, Mavillu (Mannar), Palatupana, Pessalei, Sigiriya, Trincomalee. Coelioxys (Allocoelioxys) taiwanensis Cockerell: Pasteels 1987: 232; Angunakolapellessa, Wilpattu. Megachile ardens Smith: Bingham 1897: 475 Megachile ceylonica Bingham: Bingham 1897: 482 Megachile conjuncta Smith: Bingham 1897: 482 Megachile disjuncta Fabricius: Strand 1913: 149; Nigambo, Puttalama. Megachile kandyca Friese 1918: 512; Kandy. Megachile lanata (Fabricius): Bingham 1897: 483 Megachile reepeni Friese 1918: 512; MI. Megachile relata Smith: Strand 1913: 149; Nalanda. Megachile umbripennis Smith: Strand 1913:149; Matale. Megachile vigilans Smith: Bingham 1897: 488 Megachile (Callochile) mystaceae (Fabricius): Michener 1965: 210; MI. 3 3 6 W IJESEKARA Cucumber pollination and bees In the field cucumber flowers were visited by Apis cercinci, A.clorsata, A florea , Ceratina sp., Megcichile sp., Nonna sp., Pithitis sp., Xylocopa fenestrata , X. temiiscapa and Trigona iridipennis. The most frequent flower visiting bees were Apis cerana, Ceratina sp. and Pithitis sp. Deformation of the cucumber fruits (fruits with uneven growth) was very common in the field. It was hypothesized that inadequate pollination may cause deformation of cucumber fruits. However, it was found that oviposition by the melon fly Bactocera cucurbitae on very young fruits also induced fruit deformation. To avoid melon fly attack the female flowers were covered with paper bags the day after they bloomed. The developed fruits did not have any melon fly damage but covering did not yield only undeformed fruits contributing evidence for the hypothesis o f fruit deformation due to inadequate pollination. The observational study in the net house indicated that with exclusion of pollinators there was no fruit set in the cucumber variety used. Normal growth o f fruits from all hand pollinated flowers confirmed that lack of fruit set is due to exclusion of pollinators. The low yield o f many fruit vegetables in Sri Lanka has been a concern for agriculturists who have tried to improve varieties and cultural practices to increase the yield. For example, the average yields of bitter gourd, cucumber and luffa in Sri Lanka are 5.8, 7.9, 6.7 mt /ha respectively, which is much lower than the potential yield o f these crops estimated to be 20 - 20.5 mt /ha (Anonymous, 1998). Many female flowers failing fruit set and large number of deformed fruits in the cucumber plots suggest that at least some percentage o f the gap between average and potential yield of cucumber is due to lack of adequate pollination. Although much attention has been paid to control of insect pest damages in Sri Lanka no attention so far has been paid to initial fruit set on which the final yield depends. It was observed that a large number of female flowers decayed without fruit set in all three crops mentioned above. Bees and Agriculture Honey bees have been effectively used as pollinators but the value of other bees has been less appreciated (O 'Toole, 1993). There are numerous crops that depend upon or benefit from insect pollination. Some of these crops grown in Sri Lanka includes, avocado, bean, pepper, cocoa, carambola, cardamom, cashew, cherimoya, citrus, clove, coconut, coffee, cowpea, cucubits, brinjal, grape, guava, mango, mungbean, nutmeg, okra, onion, papaya, passion fruit, peanut, bell pepper, pigeon pea, pomegranate, sesame, soybean, strawberries, sunflower and tomato (McGregor, 1976). The mechanism of how these crops benefit from pollinators is not in the purview o f this paper, BEES IN AGRICULTURE AND BIODIVERSITY 3 37 "'but the list indicates the wide range of crops that could be affected by lack of, or inadequate, pollination. There has been a general decline of bee populations around the world threatening the agriculture production and stable food supply (Allen-Warded, et cil., 1998). One o f the major contributing factors for the low bee populations is use of insecticides (Johansen, 1977). Use of these chemicals, with no concern for their effect on pollinators, kill or repel many pollinators including bees. As much as we need to use insecticides in agriculture it is necessary to regulate their use to maximize the desirable effects while minimizing the undesirable effects. Different insecticides are poisonous to bees and other pollinating agents. In Sri Lanka consideration of these adverse effects have not be recognized when recommending insecticides. Most damage to pollinators occur during the time of spraying the crops but indirect effects o f stomach poisoning by bees ingesting pollen with insecticides are also known. Hazards to bees can be reduced by application o f insecticides in the evenings when bees do not forage. While in Sri Lanka we remain ignorant of our native bees their populations may have declined or gone extinct limiting crop yields. Native bee populations in agricultural areas can be successfully manipulated to benefit crop production (Bohart, 1972). Efficiency of native bees as cop pollinators and possibility of manipulating them for agricultural production is yet to be studied in Sri Lanka. In the observational cucumber plots, nesting by a native speci es o f Megachile was su ccessfully induced using bamboo trap nests. Much research is needed on managing native bees in Sri Lanka. One of the very rewarding possibilities would be culturing of Xylocopa species for pollinating passion fruit. Xylocopa species are known to be efficient pollinators o f passion fruits (Corbet and Willmar, 1980; Nishida, 1958) and it has been shown that they can be cultured in artificial nests (Abrol, 1993; Roubik, 1995). Another species with potential in Sri Lanka is Trigona irridipennis. Results o f using Trigona ninangkabu for pollination of strawberries in net houses in Japan indicate the potential for using the local stingless bee for pollination of such crops (Katutani et al, 1993). Trigona species are known to play important role in pollination o f may crops including Mango and Rambutan (Heard, 1999). Agriculture can benefit by introduction of foreign bees. But such introductions should be carried out with utmost care after thorough studies on possible harmful effects. Bohart (1962) has discussed the value and problems of such introductions. Some adverse effects include the inadvertent introduction of arthropod diseases, parasites and predators; insects with undesirable characters such as stinging, biting people and destroying flowers and insects that molest or dispossess efficient native pollinators. When alien 3 3 8 WIJESEKARA species are introduced there is always the possibility of them establishing in the local environment. For example, in Japan a bumble bee introduced for crop pollination, Bombas terrestris, has recently been found in the wild (Keams et al, 1998). In the process foreign bees may out compete to drive some local bees to extinction, leading to cascading negative effects on biodiversity. Bees and biodiversity Bees contribute directly to the diversity of organisms in different habitats by being a group of species-rich and biologically complex insects and they indirectly help maintain the floral diversity o f these habitats by being efficient pollinators. It has been shown that the current levels of plant diversity could not be maintained in most communities if the diversity of bees was reduced (Neff and Simpson, 1993). At least 67% of the angiosperms in the world are known to depend on insects for pollination (Keams and Inouye, 1997). Different plant species are best pollinated by different species. For example Indigofera spp. are best pollinated by the species of Nomia and Pithitis bees while Callotropis are best pollinated by the carpenter bees (Xylocopa) and Garcinia by stingless Bees (Trigona) (Batra, 1993). It is necessary to identify these specific requirements and take necessary precautions to conserve bees. The flora of Sri Lanka consists of 926 endemic angiosperm species (Wijesundara, personal communications). As an efficient group o f pollinators bees can effect survival o f these plant species. Their scarcity not only reduces seed set but effects the reproduction of plants resulting in less vigorous offspring by inducing more seed setting through self pollination and reducing pollen competition (Keams and Inouye, 1997). Progenies o f plants with higher percentage o f inbred offsprings will be less adaptable to changing environmental conditions due to their low genetic variability (AllemWardel et al, 1998). Habitat fragmentation due to human activities has become a major threat to species survival in the world (Aizen and Feinsinger, 1994; Jennersten, 1998, Lamont et al, 1993). Many organisms need to have a certain minimum area o f its natural habitat for survival in the prevailing dynamic equilibrium state of the ecosystems. As in any other organism habitat fragmentation due to human activities, such as opening up o f forests, construction of dams and inundation of flood plains, and use o f pesticides are known to deplete bee diversity and their populations (Batra, 1993). Although no data available to show that it has happened in Sri Lanka we can safely assume that such development activities which have been commonplace in the country not only has led to reduction o f the forest cover to 2 2 % but also has adversely effected the native bees. BEES IN AGRICULTURE AND BIODIVERSITY 3 3 9 » Although there are 132 bee species described from Sri Lanka (almost half of them before 2 0 th century) there is no guarantee that all of them survive today. Even the surviving populations may be not o f high enough density as indicated by very infrequent visits of most native bees to cucumber flowers in observational plots. In addition to not using native bees for our advantage we inadvertently may have contributed to their demise. Hopefully it is not too late to initiate research for understanding the role o f bees in agriculture and biodiversity and thereby help feeding a healthy society. ACKNOWLEDGEMENTS The author wishes to thank Professor Jayanthi P. Edirisinghe of the Faculty of Science, University o f Peradeniya for initiating the studies on bee pollinators o f crops in Sri Lanka and for inviting his collaboration. Ms. S.L.D.K. Wijesinghe, studying for her postgraduate degree spent many hours in the field collecting flower visiting bees. Dr. Erick Grissell, Research Entomologist of the United States Department of Agriculture Systematic Entomology Laboratory and Dr. Priyantha Wijesinghe, Department of Biology, City College, City University, New York reviewed the manuscript. Dr. Charles Michner, Emeritus Professor, University o f Kansas, USA and Dr. Alain Pauly, Institute Royal des Science Naturelles de Belgique helped to make the scientific names uptodate. The help of following colleges who sent me literature which were not accesible to me is acknowledged: Dr. Nihal Rajapakse, Clemson University, USA; Dr. Marion Koterba, Berlin Museum Germany; Dr. A.W. Ebmer, Austria; Dr. Y. Hirashima, Emeritus Professor, Kyushu University, Japan; and Dr. Gabriella Chavarria, Smithsonian Institution, USA. Mr. Suranga Basnagala the research assistant to this study is acknowledged for helping in numerous ways to gather information needed to complete this study. 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