COEXISTENCE AND RESOURCE PARTITIONING BETWEEN AFRICANIZED HONEY BEES AND STINGLESS BEES (HYM, APIDAE) IN CAATINGA VEGETATION, BRAZIL

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1 COEXISTENCE AND RESOURCE PARTITIONING BETWEEN AFRICANIZED HONEY BEES AND STINGLESS BEES (HYM, APIDAE) IN CAATINGA VEGETATION, BRAZIL Maria C. Lorenzon*, José H. Schoereder**, Carlos Sperber **, Carlos A.R. Matrangolo Universidade Federal de Viçosa, Entomologia/DBA, , Viçosa, Minas Gerais, Brasil, Telefax: , * Universidade Federal Rural do Rio de Janeiro ** Universidade Federal de Viçosa, Brasil The recent breeding of African and European honeybees in Brazil, creating a hybrid called africanized honey bees, increased the discussion around a possible impact of this new variety on the decline of the populations of Neotropical native bees (Nogueira-Neto 1970, Wilms 1997). The published papers, however, do not agree regarding the competitive pressure of africanized honeybees on the wild ones and, actually, the results are more assumed than evidenced by field data. According to Roubik (1978), Sudgen et al. (1996) and Burtz Huryn (1997) there is still no demonstration that competition with honeybees affect features of other species, such as reproductive rate, death rate, resource collection, or the cost of this collection. The papers describing community structure of Apoidea (Camargo and Mazucato 1984, Martins 1990, Pedro 1991, Faria 1994, Viana 1999 among others), emphasize the species richness of the Brazilian fauna. If the Brazilian fauna is so rich, we can ask why do honey bees, present in Brazil for more than 40 years and known by their defensive behavior, still coexist with other species of bees, leading us to the hypothesis that the coexistence between honey bees and native stingless bees occurs because there is no niche overlap between the groups. The main purpose of the present research is to test how come africanized honeybees and stingless bees coexist, contrary to the predictions of niche overlap theory. Even though there are several papers describing the use similar resources by these two groups of bees, our hypothesis is that these groups do not present a significant niche overlap, which would allow coexistence. It is appropriate to remember that, even in the event of a great niche overlap between africanized honey bees and stingless bees, the competition must not be took for granted, since this process only occurs when the resources are not sufficient for the species involved. Proceedings of the 37 th International Apicultural Congress, 28 October 1 November 2001, Durban, South Africa APIMONDIA 2001 To be referenced as: Proc. 37 th Int. Apic. Congr., 28 Oct 1 Nov 2001, Durban, South Africa ISBN: Produced by: Document Transformation Technologies Organised by: Conference Planners

2 Material and Methods Study area and climatic conditions The field work was carried out in the National Park of the Serra da Capivara (PARNASCP), Piauí, Brazil (08º26'50"S, 42º45'51"W). The Park has a typical caatinga vegetation, with a transition for a cerrado vegetation. Both vegetation types are savanna-like formations, the former being characteristic of dry climate of northeastern Brazil, and the latter is more common in the center of the country, occurring in more wet conditions. The Park has 129,140 ha and is situated between the arid and semi-arid vegetation distribution. The annual average temperature is 28 ºC and the annual average precipitation is 689 mm. Around the Park there are about 500 commercial honeybee apiaries, making this site an excellent study system due to the existence of an area of intensive impact of honeybees from the artificial beehives, apart from an area without the influence of these apiaries, but still with natural africanized honey bee nests. Sampling sites The collections were carried out inside the Park in two sampling sites. The first site was located near honeybee apiaries, in a maximum distance of 2 km. The second site was located more than 15 km apart from the first site, to guarantee the absence of honeybees from the apiaries. This site has, nonetheless, the influence of africanized honeybees that nest in the area, without man s care. The sites were positioned with the aid of a GPS, to avoid distances of less than 15 km, which are greater than the average flight distance of honeybees. We sampled an area of 1.5 ha in each site, using three 400 x 4 m transects. The sampling point was the flowering plants. The sampling Field sampling was carried out each 21 day intervals, in 1998 and 1999, using two people in daytime, from 6 a.m. to 6 p.m. a) Bee sampling: Two people slowly walked along the transect, in the morning and in the afternoon. The sampling method used was based on Sakagami et al. (1967). The collectors stopped for 5 min in each flowering plant, collecting the bees with an entomology net. Collected specimens were put in individual deadly flasks, pricked, labeled, and registered the vulgar name of the plant, the number of the plant, date, collection time and the density of bees visiting to the floral species under observation. b) Plant sampling: From each plant species visited by bees we collected the number of specimens in each site and time of flowering. When there is too many flowers, we estimated the density from five samplings in a 10 x 10 m quadrate. Each species have four voucher specimens, deposited in the Botany Museum of the Universidade Federal Rural de Pernambuco.

3 Data analysis a) Analysis of trophic niche overlap: The trophic niche of each bee group was considered the number of plant species visited by foraging bees, as well as their number of times each bee group was observed visiting each plant species. These data were plotted in a graph for the visualization of the trophic niche of the africanized and stingless bees, and their niche overlap. The trophic niche overlap was calculated using a Kolmogorov-Smirnov test, which tested the median value of resource use in the shape of resource use distribution. Our null hypothesis was that the frequencies of resource use are the same for the two bee groups. Our working alternative hypothesis is that the trophic niches differ. The test was carried out for 1) both sampling sites together, 2) each sampling site, 3) for each bee group (stingless and africanized bees), in the two sampling sites. b) Analysis of stingless bee abundance and species richness in relation to the density of africanized bees: The explanatory variables analyzed were: (1) sampling sites (with and without the influence of apiaries), (2) sampling season (dry and rainy season) and (3) africanized bee abundance. The influence of these variables was tested on the response variables: stingless bees (1) abundance and (2) species richness. We carried out analyses of covariance, with Poisson errors. To test for analyses power we carried out tests of distribution of residuals (Crawley 1993). We tested the null hypothesis that our explanatory variables do not explain the variations observed in the response variables. Results Floral resources exploited by africanized and stingless bees in the sampling sites: In the site A1 (close to the apiaries) we sampled 65 flowering plant species. From these, 11 and 27 were foraged by africanized and stingless bees, respectively. In site A2 (without apiaries) we collected 82 flowering plant species, and africanized and stingless bees used 22 and 38, respectively. In these two sites there is a low plant usage by the bees (larger than 50%), even though we consider variations in plant height, site and flowering season. The bees forage more during the rainy season, showing that this period is the more abundant in flowering plant species, including the plants used by both africanized and stingless bees. Abundance and species richness: 1527 individuals were collected, being 725 africanized bees and 802 stingless bees. We sampled 12 stingless bee species were: Melipona asilvae, M.quinquefasciata, Trigonisca sp., Plebleia flavocincta, Friseomielitta silvestrii, F. flavicornis, Partamona sp., Paratrigona lineata, Trigona sp., Trigona spinipes, T. recursa, Carmagoia nordestina. These species were grouped for the comparisons with africanized bees because they form a subfamily with common features, and because of the hypothesized influence of africanized bees on stingless bees as a whole.

4 Is there niche overlap between stingless bees and africanized bees? How does this process happen at the sampling sites? Figure 1 presents all resources foraged by Apoidea, emphasizing trophic niches of africanized and stingless bees, organized by decreasing frequency of visitation by africanized bees. We verify that niche overlap between africanized and stingless bees occur in most resources exploited by africanized bees, although the overlap represents a small proportion of stingless bee niche Frequencies of resource use by the bees Africanized honeybees Stingless bees Sequence of species of plants visited or not by the bees Figure 1 - Sequence of species of plants visited by africanized and stingless bees, organized according to the decreasing order of visitation frequency of africanized bees. There is no significant niche overlap between africanized and stingless bees (p<0.01), when we considered the two sampling sites together. When the two sampling sites are considered separately, however, there is a significant niche overlap between africanized and stingless bees in the site A1 (with apiaries) (p<0.001), but not in the site A2 (without apiaries) (p>0.05). When the groups were analyzed separately, there is no significant difference between the niches of stingless bees in the two sites (p>0.05), but the niche of the africanized bees in the site A2 is significantly larger than in the site A1 (p<0.05).

5 Variables affecting stingless bee abundance and species richness: There is a significant positive relationship between stingless and africanized bee abundance, even when there is an interaction between these variables with site and season (r 2 =0.64, p<0.001). Stinglees bee species richness, however, did not have a significant relationship with africanized bee abundance, although there is a significant relationship of the interaction of africanized bee abundance and season (r 2 =0.30, p<0.002). These results indicate that the abundance of africanized bees do not affect stingless bee abundance and species richness. Discussion The coexistence between africanized honey bees and stingless bees: The theory of the Differentiation of the Niche predicts that different species have more coexistence probability, and this can also be considered to explain the coexistence in bee community. According to Michener et al. (1978) and Loken (1981) several stingless bee species coexist because they present different morphological, behavioral, physiological and ecological strategies. The coexistence between stingless and africanized bees, nonetheless, is controverse because the latter bees present high populations and dispersal rates. Our data evidenced an influence of africanized bee abundance on the stingless bee abundance in some sites and seasons. According to Paton (1993) this pattern may not be sufficient to identify the occurrence of competition. It is also necessary to verify the response of stingless bees to the abundance of africanized bees, and if this response causes a shift in the foraging pattern of stingless bees in the presence of africanized bees (Roubik 1983, Schaffer et al. 1983). Do niches of stingless bees differ under influence of africanized bees? Resource partitioning between the two bee groups, which belong to the same guild, makes improbable a reduction in niche overlap, because of the several similarities in taxonomic aspects, social structure and in the generalist foraging strategy of these bees. Several authors (Schaffer et al. 1983, Roubik 1978, 1980, Westrich 1989, Thorp 1996, Weslo and Cane 1996) consider that, as stingless and africanized bees use similar resources, africanized bees always affect stingless bees, because the former is an introduced species. This hypothesis considers the niche overlap shift to indicate negative interactions between the groups. When we analyze trophic niche overlap between africanized and stingless bees, we verified a shift in the structural foraging pattern in the sampling sites. This shift occurred only in the africanized bees: in the site without the influence of the apiaries their niche is larger than in the site with apiaries influence. The described shift did not alter stingless bee niche width. Are africanized bees probable competitors with stingless bees? According to Roubik (1983) and Schaffer et al. (1983) the alteration of stingless bee trophic niche within the presence of africanized bees is an important effect of competition, although we did not observe this effect. We

6 argue that since the involved groups of bees are similarly generalist and opportunist, a small niche overlap may occur in the most abundant plant species, which would affect the species with low abundance, represented by some species of stingless bees. When we analyze the plant resources foraged by the bees in the two sampling sites, we verified that in the site close to the apiaries 38 plant species were used by bees, although only seven are used in common by both groups. In the site without the influence of the apiaries, bees used 60 plant species, and only 13 were used in common by both groups. Analyzing the seasonal fluctuation of the plant flowering, we noticed that in the period of larger abundance four species presented high floral density, and there is a small overlap of use of the resources by both stingless and africanized bees. Heterogeneity of flowering plant species may be an important factor in the coexistence of the groups, because it maintains a permanent spatial variation, reducing species interactions and favoring the occurrence of different species in different environmental patches. This favors the hypothesis that floral resources are abundant, even when we consider that several plant species may not be used by some bee species, because they do not allow efficient exploitation. In the studied region there is a period of flowering plant abundance, when the niche overlap is higher, and a period of shortage, when competitive interactions are more probable. In the period of shortage, however, africanized bees usually migrate (Michener 1975), reducing the probability of negative interactions in this community. Additionally, according to Schwarz and Hurst (1997), africanized bees may have a positive effect on stingless bees, because they saturate the local predators and releasing the predation influence on stingless bees. This reasons indicate that interspecific competition may not always occur between africanized and stingless bees. All the presented evidence shows that the mechanism responsible by the coexistence between these bees is the abundance and seasonality of the resources exploited by the bees. Conclusions 1. When there is abundance in trophic resources, there are plant species exclusively exploited by africanized bees, and other plant species exclusively foraged by stingless bees, although there is a small trophic niche overlap; 2. The chances of competition between africanized and stingless bees is small in the flowering season; 3. Africanized bee abundance do not interfere in stingless bee abundance, nor in their species richness;

7 4. Variations in visitation frequency of africanized bees in the flowers do not modify stingless bee trophic niche; 5. There is no evidence of competition effect between africanized honey bees and stingless bees; 6. The shift in the pattern of resource use by africanized bees may be indicative of intra-specific competition. References Butz Huryn V.M Ecological impacts of introduced honey bees. Q. Rev Biol 72: Camargo, J.F. e M. Mazucato Inventário da Apifauna e flora apícola de Ribeirão Preto, SP. Dusenia, 14 (2) : Crawley, M.J Glim for Ecologists. Oxford, Blackwell Scientific Publications, 379 p. Faria, G A flora e a fauna Apoidea de um ecossistema de campo rupestre, Serra do Cipó MG: Composição, fenologia e suas interações. Tese de Doutorado.UEP, Rio Claro, SP, 239 p. Johnson L.K. e Hubbel S.P Contrasting foraging strategies and coexistence of two bee species on a single resource. Ecology, 56: Loken A Flower visiting insects and their importance as pollinators. Bee World. 62: MacArthur R.H Geographical Ecology. Harper & Row, Pub. New York, 230 p. Martins, C. F Estrutura da comunidade de Abelhas (Hym: Apoidea) na caatinga (Casa Nova, BA) e na Chapada Diamantina (Lençois, BA). Tese de Doutorado. USP, 159p. Michener C.D., M.L.Winston, R.Jander Pollen manipulation and related activities and structures in bees of the family Apidae. Univ. Kansas Sci. Bull. 51: Nogueira-Neto P A criação das abelhas indígenas sem ferrão. Ed Chácara e Quintais, SP. 220 p. Paton D. C Honeybees in the Australian Environment: Does Apis mellifera disrupt or benefit the native biota. Bioscience, 43(2): Pedro S.R.M Sobre as abelhas (Hym., Apoidea) em um ecossistema de cerrado (Cajuru, SP): composição, fenologia e visita às flores. Tese de Mestrado, FFCLRP, Ribeirão Preto, São Paulo, 200p. Roubik D.W Experimental community studies: time-series tests of competition between African and Neotropical bees. Ecology, 64 (5), Roubik D. W Experimental community studies: time-series tests of competition between African and neotropical bees. Ecology, 65: Sakagami S.F., S.Laroca, J.S.Moure Wild bee biocenotics in São José dos Pinhais (PR), South Brazil Preliminary report. J. Fac. Sci. Hokkaido Univ., Ser. 6, Zoology, 18: Schaffer W.M, D.W.Zeh, S.L.Buchmann, S.Kleinhans, M.V.Schaffer, J.Antrim Competition for nectar between introduced honey bees and native North American bees and ants. Ecology, 64: Schwarz M.P., P.S. Hurst Effects of introduced honey bees on Australian s native bee fauna. The Victorian Naturalist, 114 (1):7-12. Sudgen E.A., R.W.Thorp, S.L.Buchmann Honey bee-native bee competition: focal point for environmental change and apicultural response in Australia. Bee World 77: Thorp R.W Resource overlap among native and introduced bees in California. In: Matheson A., S.L.Buchmann, C.O Toole, P.Westrich, I.H.Williams (Eds).The Conservation of Bees. Academic Press, London. 450p Viana B.F A comunidade de abelhas (Hymenoptera: Apoidea) das dunas interiores do Rio São Francisco, Bahia. An. Soc. Entomol. Brasil., 28(4): Weislo W.T. e J.H. Cane Floral resource utilization by solitary bees (Hymenoptera: Apoidea) and exploitation of their stored foods by natural enemies. Ann. Rev. Entomol, 41: Westrich P Die Wildbienen Baden-Wurttembergs. Ulmer, Stuttgart Wilms W., B. Wiechers Floral sources partitioning between native Melipona bees and the introduced africanized honey bee in the Brazilian Atlantic rain forest. Apidologie, 28:

8 COEXISTENCE AND RESOURCE PARTITIONING BETWEEN AFRICANIZED HONEY BEES AND STINGLESS BEES (HYM, APIDAE) IN CAATINGA VEGETATION, BRAZIL Maria C. Lorenzon*, José H. Schoereder**, Carlos Sperber **, Carlos A.R. Matrangolo Universidade Federal de Viçosa, Entomologia/DBA, , Viçosa, Minas Gerais, Brasil, Telefax: , *Universidade Federal Rural do Rio de Janeiro ** Universidade Federal de Viçosa, Brasil Curriculum Vitae Name: Maria Cristina Lorenzon Nacionality: Brazil (Rio de Janeiro State) Birthday: 22/05/1955 High School: Universidade Federal Rural do Rio de Janeiro 1977 Specialization Courses : MSc Entomology - Universidade Federal de Viçosa, Brazil 1989 DSc Entomology Universidade Federal de Viçosa, BraziL in course Techician assistance Apiculture and Meliponiculture (stingless bees) Business in many states of Brazil Professor of the Universidade Federal Rural do Rio de Janeiro (Brazil) since Specialization Session : ecology of bees, management of africanized honey bees and stingless bees. Scientific Publications 1. Pollinators in Allium cepa L. bloom, Revista da Sociedade Entomológica do Brasil. v 21(3): , Bee Pollination and production of Allium cepa hybrid seeds, Pesquisa Agropecuária Brasileira, v.28(2): , Trigona spinipes behavior during visits in Allium cepa L bloom. Pesquisa Agropecuária Brasileira, v.28(2): , Characterization and floral stadiums of the parental lineages of the hybrid onion", Revista Ceres., v.40(25): , Fertility of the pollen in parental lineages of the hybrid onion, Revista Ceres, v.41(234): , 1994, 6. Apis mellifera behavior during visits in Allium cepa bloom Revista Ceres, v.15 (232): , Behavior of the africanized honey bees during pollination in greenhouses of Allium cepa Pesquisa Agropecuária Brasileira, v.29 (11), , IV Congress American Latin Iberian of Beekeeping, Córdoba (Argentina ), may, 1994 : 1) Production of honey from africanized honey bees in Cashew bloom. (Anacardium occidentali L.); 2) Trigona spinipes x Apis mellifera (Hym: Apidae) visiting Hybrid Allium cepa flowers, 3) Schedule to development the exploration of the africanized honey bees and stingless bees in the Paraíba State (Brazil); 4) Loosen of the africanized honey bees colonies in a semi-arid ecosystem ; 5) Antimicrobial activity of honey from Partamona cupira (Meliponinae) th International Apicultural Congress -Pollination Requirements of Acerola (Malpighia glabra L.), Lausanne, August/ XI Brazilian Congress of Beekeeping, Piauí: 1) Distribution of the africanized honey bees and stingless bees natural nests in a semi-arid ecosystem. 2) Competition between Melipona subnitida and africanized honey bees ) in a semi-arid ecosystem; 3) Pollinators of Malpiglia glabra L. in a semiarid ecossistem, 4) Trigona spinipes damaging Malpighia emarginata ; 11. Adaptability Test of Tetragonisca angustula bees, when moving these colonies to tropical region, Scientific Symposium for beginners, Rio de Janeiro, Brazil, 12. XXXII International Congress of Beekeeping, Vancouver, Canada: 1) Does Latitudinal Effect Exist in Bee Species Richness? 2) Flora Heterogeneity, a Factor that affects the Apis Production, August/1998.