The International Journal Of Science & Technoledge (ISSN 2321 – 919X) www.theijst.com

THE INTERNATIONAL JOURNAL OF SCIENCE & TECHNOLEDGE

Bee Inventory and Distribution in the Forest Savannah Transition Zone of Ghana

Dr. Eddiebright Joseph Buadu Lecturer, Department of Mathematics and Science Education College of Distance Education, University of Cape Coast, Ghana Peter Kofi Kwapong Professor (Head), Department of Conservation Biology and Entomology, University of Cape Coast, Ghana

Abstract: Wild ensure the delivery of pollination services and the maintenance of biodiversity in agricultural and natural landscapes. A study to identify bees in the Forest Savannah Transition Zone (FSTZ)of Ghana and determine their distribution was carried out from June 2013 to April 2014. The study area was divided into upper, middle and lower FSTZs on the basis of the proportion of trees relative to grasses. Three landscapes types namely agricultural land, natural vegetation and settlement fringes were identified and replicated within each of the three subzones giving a total of 18 sampling sites. Traps were set along a 500m x 3m transect constructed in each site. Bees were sampled along these transects using coloured pan traps (blue, white and yellow) and sweep net. In all, 706 bees, made up of three families (, Halictidae and Megachilidae) 18 genera and 34 species were collected. Five of the 34 species were represented by single individuals (singletons). Apis mellifera (Linnaeus) was the most ubiquitous species occurring in all subzones and landscape types. Bees were variously distributed in response to the availability of resources in both space and time. Whereas some species were limited to a particular subzone, others were restricted to a specific landscape type.

Keyword: Abundance, bees, diversity, pollination, nesting, natural vegetation

1. Introduction Pollination contributes to food security, biological diversity and the economy. Bees, the main pollinators of wild and agricultural plants in most ecosystems (Buchmann & Nabhan, 1996; Ollerton, Winfree & Tarrant, 2011), are currently suffering considerable declines in abundance and species richness (Steffan-Dewenter, Potts & Packer, 2005; Biesmeijer et al.,2006). Landscape change is one cause of fragmentation, which may decrease bee abundance and species richness (Jennersten, 1988, Steffen-Dewenter & Tscharntke, 2002). Studies conducted in Central Europe and the US show that bee diversity and abundance is influenced by the structure and composition of the surrounding landscape (Tscheulin,Neokosmids,Petanidou,& Settele,2011). In Ghana, many food and cash crops are grown in the FSTZ among which are yam ( Discorea alata ), plantain ( Musa sapien ), maize ( Zea mays ), watermelon (Citrullus lanatus ), ( Lycopersicon esculentum ), ( Solanum melongena ), pepper ( Capsicum annum ), cucumber (Cucumis sativus ), mango ( Mangifera indica ), cashew ( Anarcadium occidentale ); and several other fruits, vegetables and horticultural crops. Many of these crops including mango, cashew, cucumber, eggplant, tomato, pepper and water melon are pollinated by bees. In fact, the FSTZ is often referred to as the ‘food basket’ of Ghana. Yields of these crops have been insufficient in recent times and these could be attributed to widespread human activities in the study area including wildfire, logging, mining and urbanization. Human activity, based on the assumption that pollination is a free and abundantly available ecosystem service, has put a large pressure on pollinators by both increasing their demand and removing their habitat (FAO, 2008). It is believed that humans have modified greater than 50% of the Earth’s land surface and this is but one change; others include changes in composition of air and water, and loss of overall biodiversity (Hooke & Martín-Duque, 2012). Biodiversity, therefore, is being exploited at much faster rates than ever before with negative implications for sustainable human livelihood (Turner, Clark, Kates, Richards, Matthews, & Meyers, 1990)). A report by Wuver and Attuquayefio (2006) indicated that major human activities that impact on biodiversity are bushfires, hunting, fuel wood harvesting and agriculture. It is feared that similar activities which are very pervasive in the FSTZ of Ghana might alter the landscape and affect bee populations. Many studies have confirmed that diverse communities of pollinators (mainly wild bees) provide more effective pollination services to crops and wild plants than less diverse communities (Breeze, Bailey, Balcombe & Potts, 2011). In addition, research has shown that yields of insect-pollinated crops are more unstable when the pollinator community (in a region) consists of fewer species (Garibaldi, Aizen, Klein, Cunningham & Harder, 2011). Regrettably, no study to my knowledge has been conducted to identify and determine the status of bees in the different zones and landscapes within the FSTZ of Ghana. Across landscapes, bee abundance and richness change in response to floral diversity which is also linked to environmental cues such as temperature and precipitation (Welch, 2011).

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Knowledge of bees and their occurrence in the FSTZ of Ghana are a prerequisite for identifying the areas that need to be preserved, managed, or supplemented to keep bee populations at levels that will ensure sustainable food production. The general objective of the study was to assess the status of wild bees in the FSTZ of Ghana. The specific objectives were (1) to identify bee species occurring in the FSTZ of Ghana; (2) to determine bee distribution across subzones and landscape types within the FSTZ of Ghana, and (3) to determine bee abundance in three different subzones in relation to richness across landscape types.

2. Materials and Methods

2.1. Study area and Field work The research was conducted on a bi-monthly basis within the FSTZ of Ghana (Fig 1) from June 2013 to April 2014.

Figure 1: Communities sampled within the FSTZ of Ghana Source: Modified from http://www.apipnm.org

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The study area was divided into three subzones or blocks based on the proportion of tree-to-grass vegetation. The upper FSTZ (Awisa and Subinso) constitutes the northern portion with the highest percentage grass cover whilst the south with the highest percentage tree cover was named the lower FSTZ (Nyameadom and Mankranso). The middle FSTZ (Kobedi and Yawhima) comprise the midsection with approximately equal proportions of grasses and trees. Three landscape types namely agricultural land, settlement fringes and natural vegetation were identified and replicated in each subzone (Table 1). According to Turner, Gardener and O’Neill (2001), the term landscape refers to an area of land spatially heterogeneous in at least one factor of interest.

Locations Subzone 1 2 Landscape type Agricultural land Upper FSTZ Awisa Subinso Settlement fringes Natural vegetation Agricultural landscape Middle FSTZ Kobedi Yawhimah Settlement fringes Natural vegetation Agricultural landscape Lower FSTZ Mankranso Nyameadom Settlement fringes Natural vegetation Table 1: Subzones, Locations and Landscape types studied within the FSTZ of Ghana Upper FSTZ-towards the savannah region; Lower FSTZ- towards the forest region; Middle FSTZ- lies between the lower and upper transition zones.

At each site, a 500m by 3m fixed transect was constructed and a set of three5.08cm PVC pipes erected at intervals of 100m along each transect (Fig 2). The pipes were placed in a triangular form with each separated from the other by a distance of one metre and projecting one metre high above the surface of the ground.

Figure 2: Diagrammatic representation of the sampling protocol in each transect

2.2. Bee Sampling Two complementary methods (pan trapping and netting) used by Potts et al. (2005) and Munyuli (2012a) were adopted to sample bees from flowering plants. Bee communities are best sampled when pan-trapping is used concurrently with aerial netting (Wilson,Griswold, & Messinger, 2008). It has been established that the pan trapping technique is easy to use by researchers with varying levels of entomological experience (Leong & Thorp, 1999). Westphal, Bommarco, Carre´, Lamborn and Morison (2008) established that the pan trap method is the least biased and most successful technique for collecting bees.Pan traps of the colours yellow, white and blue (Droege et al., 2010) were filled with soapy water and placed on the PVC pipes for 48 hours during each sampling visit. Bees caught in pan traps were collected the third day and preserved in vials containing 70% alcohol. In addition, a 45- minutewalk was taken along each transect the second day and any bee found on plants occurring within 2m radius on either side was netted. After each sampling period, the samples collected were transported to the University of Cape Coast (UCC) Entomology Museum where the different bees collected were sorted out and pinned for identification and storage.The bee species identified were counted and corresponding figures indicated in a frequency table.

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3. Results

3.1. Bee Occurrence and Distribution in the FSTZ of Ghana Using the two sampling methods, a total of 706 bees made up of 3 families, 18 genera and 34 species were identified (Table 2). The families were Apidae (18 species), Halictidae (11species) and Megachilidae (5 species).

No. Family Genus Species 1 Apidae Apis Apis mellifera (Linnaeus, 1758) 2 ,, Amegilla cingulata (Fabricius, 1775) 3 ,, ,, A.calens (Lepeletier,1841 ) 4 ,, ,, A. acraensis (Fabricius,1793) 5 ,, ,, A. albocaudata (Dours,1869) 6 ,, ,, A. nila (Eardley,1994) 7 ,, Meliponula Meliopnula bocandei (Spinola, 1853) 8 ,, Compsomelissa Compsomelissa nigrinervis (Cameron, 1905). 9 ,, Ceratina Ceratinamoerenhouti (Vachal, 1903) 10 ,, Thyreus Thyreus nitidulus (Fabricius, 1804) 11 ,, Allodape Allodape interrupta (Vachal, 1903). 12 ,, Braunsapis Braunsapis leptozonia (Vachal, 1909) 13 ,, Xylocopa Xylocopa imitator (Smith, 1854) 14 ,, ,, X. albiceps (Fabricius, 1804) 15 ,, ,, X. olivacea (Fabricius, 1778) 16 ,, ,, X. nigrita (Fabricius, 1775) 17 ,, ,, X.hottentota hottentota (Smith, 1854) 18 ,, ,, X. torrida (Westwood, 1838) 19 Halictidae Lipotriches Lipotriches orientalis (Friese, 1909) 20 ,, ,, L. natelensis (Cockerell, 1916) 21 ,, ,, L. nigrociliata (Cockerell, 1932) 22 ,, ,, L. tetraloniformis (Strand, 1912) 23 ,, ,, L. cirrita (Vachal, 1903) 24 ,, ,, L. guinensis (Strand, 1912) 25 ,, Pseudapis Pseudapis amoenula (Gerstacker, 1870). 26 ,, Halictus Halictus sp. 27 ,, Nomia Nomia ivorensis (Pauly, 1990) 28 ,, ,, N. viridicincta (Meade-Waldo, 1916) 29 ,, Lasioglossum Lasioglossum quebecensis (Crawford, 1907) 30 Megachilidae Megachile Megachile semierma (Vachal, 1903) 31 ,, ,, M. bituberculata (Ritsema, 1880) 32 ,, Chalicodoma Chalicodoma cincta (Fabricius, 1781) 33 ,, Coelioxys Coelioxys torrida (Smith, 1854). 34 ,, Lithurgus Lithurgus sparganotes (Schetterer, 1891) Table 2: List of bees collected from the FSTZ of Ghana from June 2013 to April 2014

Among the 34 bee species identified, Apis mellifera (Linnaeus) was the only one found in all subzones and in each of the three landscape types (Table 3).

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SPECIES NAME UPPER FSTZ MIDDLE FSTZ LOWER FSTZ No. AGR. SET. NAT. AGR. SET. NAT. AGR. SET. NAT. 1 Apis mellifera √ √ √ √ √ √ √ √ √ 2 Amegilla cingulate × × √ √ × × √ √ × 3 Amegilla calens √ × √ × √ √ √ × √ 4 Amegilla acraensis × × √ × × × √ √ × 5 Amegilla albocaudata × √ × × × × √ × × 6 Amegilla nila × × × √ × × √ × × 7 Meliponula bocandei × × √ × × × × × × 8 Compsomelissa nigrinervis √ × √ × × × × × × 9 Ceratina moerenhouti √ × × √ × × × √ × 10 Thyreus nitidulis × × × × × × × √ × 11 Allodape interrupta √ √ × √ × √ × √ × 12 Braunsapis leptozonia × √ √ × √ × × √ × 13 Xylocopa imitator √ × √ × × √ √ × √ 14 Xylocopa albiceps √ √ × × × × √ √ √ 15 Xylocopa olivacea √ × √ √ × √ √ √ × 16 Xylocopa nigrita × × × × × × √ √ √ 17 Xylocopa hottentota × × × × √ × √ × √ 18 Xylocopa torrida √ × × × × × √ × × 19 Lipotriches orientalis × × × × × √ √ × √ 20 Lipotriches natelensis × × × √ √ × √ √ √ 21 Lipotriches nigrociliata × × × × × × √ √ × 22 Liporiches tetraloniformis × × × × × × × √ × 23 Lipotriches cirrita √ × × × × × × × × 24 Lipotriches guinensis √ × √ × × × × √ × 25 Pseudapis amoenula × √ × √ × × √ × × 26 Halictus sp. √ × × × √ × √ × × 27 Nomia ivorensis × √ √ × × × √ × × 28 Nomia viridicincta × × × √ × × √ √ × 29 Lasioglossum quebcensis √ × × × × × √ √ × 30 Megachile semierma × × × × × × √ √ × 31 Megachile bituberculata × × × × × × √ √ × 32 Chalocodoma cinta × × × × × √ × × × 33 Celioxys torrida × × × × × × × × √ 34 Lithurgus sparganotes × × × √ × × × × × Table 3: Bee species distribution among landscape types and subzones

KEY: AGR, SET and NAT refer respectively to agricultural land, settlement fringes and natural vegetation. √= Present × = Absent 1 Species occurring in all areas 2 Species occurring in a single landscape 3 Species occurring in a single subzone

Apis mellifera thus appear to be the only bee that does not discriminate in occurrence. Nineteen species were found in more than one landscape type or subzone but not in all landscape types and subzones. The remaining fourteen species were either found in a single landscape type or a single subzone. Nine species were found in a single landscape type and these were Amegilla nila , Xylocopa torrida , Lipotriches cirrita and Lithurgus sparganotes which occurred in only agricultural land. The rest were Meliponula bocandei, Coelioxys torrida, Chalocodoma cinta , Thyreus nitidulis and Lipotriches tetraloniformis . The first three of these species were found in natural vegetation only whilst the last two occurred only in settlement fringes. Five bee species occurred in a single subzone but not a single landscape type. These were Xylocopa nigrita , Lipotriches nigrociliata , Megachile semierma , Megachile bituberculata and Compsomelissa nigrinervis . The first four species occurred in the Lower FSTZ whilst the last was limited to the Upper FSTZ. To sum up, 4 bee species were found in only agricultural land, 3 species in only natural vegetation and 2 species in only settlement fringes. With subzones, 1 species was limited to the upper FSTZ and 4 to the lower FSTZ. No species was limited to the Middle FSTZ only. Five out of the 34 bee species were represented by single individuals (singletons). The lower FSTZ had three singletons which were L. tetraloniformis , T. nitidulis and C. torrida. The Middle FSTZ also recorded two singletons namely L. spaghanotes and C. cinta . No species was represented by a single individual in the Upper FSTZ.

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3.2. Bee Abundance per Subzone versus Species Richness across Landscape Types Though the upper FSTZ recorded the highest bee number (abundance) it obtained the highest richness only in natural vegetation (11 species)among the three subzones. The lower FSTZ registered was second in terms of bee numbers but obtained the highest richness in two landscapes in agricultural land (22 species) and settlement fringes (18 species) (Table 4).

Species riches Subzone Bee Abundance Agricultural land Settlement fringes Natural vegetation Upper FSTZ 286 13 7 11 Middle FSTZ 146 10 6 7 Lower FSTZ 274 22 18 9 Table 4: Bee abundance per subzone versus species richness across landscape types

It thus appear that the lower FSTZ offers the most ideal conditions for bee habitation. The middle FSTZ was not only the lowest in abundance among the subsones but also the lowest in species richness across the three landascapes. Thus, higher abundance does not automatically translate into higher richness as the two represent different measures of biodiversity.

4. Discussion This research examined bee species distribution within the FSTZ of Ghana. A total of 706 bees made up of 3 families, 18 genera and 34 species were collected and identified. The dominance of Apismellifera over the other bee species could be attributed to its generalist foraging behaviour, physique and perennial large colonies (O’ Toole & Raw, 1991). A. mellifera feeds on a wide range of floral resources (polylectic) and this enables it to survive in varied environments. Its social behaviour and occurrence in large numbers makes it a highly successful bee. Being a long-distance forager, A. mellifera is able to visit distant and sparsely distributed floral-rich patches far removed from their hives. Even though honeybees have on the average, a foraging range of about 3km, a study carried outin the Congo forest indicated that they can sometimes forage up to a distance of 25 km away from their hives (Roubik, 2001). The other bee species differed in their occurrence with some species being very rare. There is an increasing body of evidence suggesting that nest sites and nesting resources are important factors determining bee species distribution (Potts et al., 2005). Bees exhibit a diverse array of nesting strategies with respect to the part of the habitat they nest in, the type of substrate they use, and the materials required for nest construction (O’Toole and Raw, 1991). According to O’Toole and Raw, bees are extremely diverse in their nesting ecology and comprise a number of distinct guilds: miners, carpenters, masons, social nesters and cuckoos. The diversity of nesting strategies and the specialization of guilds means that the availability of the correct quantity and quality of resources, both in space and time, are key in determining which species a landscape will support (Steffan-Dewenter, Potts& Packer,2005). The occurrence of certain bee species in specific landscape types and subzones may have been in response to the availability of the required resources in both space and time. Species rarity is common in bee fauna. Studies conducted to document bee fauna in several parts of the world have reported high proportions of singletons and doubletons (Williams,Minckley& Silveira, 2001). According to Manuel, Roubik, Finegan and Zamora (1999), rarity of native bees is common in open or exposed sites particularly among the ground nesters. For example, most species of Lasioglossum were found mostly in farmlands where bare nesting sites were more readily available. Apart from Lithurgus spaghanotes which is a wood nester, the remaining four single tons namely Lipotriches tetraloniformis , Thyreusnitidulis, Chalicodoma cinta and Coelioxys torrid a are ground nesters. Timberlake, cited in Michener (1979) observed that even with intensive sampling bee species rarity can still reach high levels comprising between 16 and 42%. Again, pollinator population rises and falls, as do all , in response to environmental variables such as weather conditions, levels of parasitism, or abundance of nesting sites. Thus, it is not unusual to record singletons and doubletons in population studies. It is also possible that the number of bees collected could probably have been higher but for the high levels of human-mediated activities including small scale mining occurring in these areas. According to Kremen et al (2007), bees, the most important group of pollinators, are affected by human disturbances such as habitat loss, grazing, logging, and agricultural intensification. Pesticides usage, bushfires, logging, mining and grazing are quite common in the FSTZ of Ghana and may have negatively affected wild bee species abundance and richness. Most farmers in the FSTZ apply herbicides probably due to the ease with which land dominated by grasses (herbs) can be cleared with weedicides especially during the immature stages. Insecticides pose a major threat to pollinators, and pesticide-induced declines in bee populations are yearly reported in many countries of the world (Williams et al., 2010a). The use of fire to clear the land of weeds is a common practice in the FSTZ of Ghana. Fire is applied for three major reasons: to clear the land for the new planting season, to regenerate fresh forbs for livestock or for hunting game. Many farmers in the study area engage in this activity probably because they find it easier and cheaper compared to hiring labour. This has both direct and indirect implications for biodiversity. Fire not only kills pollinators but also destroys their forage and nesting resources (Potts et al., 2003). Another activity common in the study area is logging. There are several wood processing companies doing brisk business within the FSTZ zone. Their activities have the potential of depleting the FSTZ of diverse tree populations at a very fast rate thereby denying bees especially wood nesters of shelter, nesting materials and food resources the same way as bushfires. Small-scale surface mining presently appears to pose the greatest threat to the FSTZ of Ghana. The activities of small-scale surface miners have resulted in the destruction of the surface soil and several wetlands which could serve as forage and nesting sites for bees. This has the tendency to cause declines in wild bee populations leading to lower food production.

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Generally, it is admitted that grazing intensity (stocking density of animals) can affect the pollinator species richness, abundance and visitation frequency to flowering plants through changing the structure, composition and phenology of preferred bee-food plants (Xie,Williams,& Tang,2008)). Most rural homes in Ghana leave their domestic animals to roam freely rendering settlement areas unstable and depriving pollinators of the needed floral and nesting resources.

5. Conclusion The study collected a total of 706 bees, made up of three families (Apidae, Halictidae and Megachilidae) 18 genera and 34 species. Apidae is the most speciose bee family in the FSTZ and Apis mellifera the most ubiquitous species, occurring in all subzones and landscape types. The bees were variously distributed across the FSTZ determined perhaps by factors such as food and nest sites. The lower FSTZ appeared to possess the most favourable factors and hence the most bee preferred subzone. Many more different bees could possibly have been collected from the study area but for the prevailing human activities. The high proportion of singletons or doubletons could mean that these species are getting either endangered or were undetected. Further monitoring is required before firm conclusions on their status could be drawn. Nevertheless, the baseline data generated highlight the need to intensify pollinator education throughout the country and also conduct regular pollinator appraisal in all the major agro-ecological zones of Ghana so that specific bee conservation measures could be applied in the most relevant areas to safeguard food security in the country.

6. Acknowledgements We are grateful to Dr. Rofela Combey, a bee taxonomist and a senior lecturer in the Department of Conservation Biology and Entomology through whose effort the bees were identified. A special thank you is expressed to the College of Distance Education (CoDE), University of Cape Coast, Ghana for providing the funds used to undertake this study. Finally, we are grateful to the traditional authorities of the study communities for their cooperation and support.

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