755 Community Structure of Social Wasps (Hymenoptera: Vespidae) in Riparian Forest in Batayporã, Mato Grosso do Sul, Brazil by Maria da Graça Cardoso Pereira Bomfim1 & William Fernando Antonialli Junior1,2 ABSTRACT Reduction and destruction of riparian forests are harmful to the biota, especially the social wasps. This study analyzed the species constancy and the structure of the polistine wasp community associated with fragments of riparian forest in the municipality of Batayporã, state of Mato Grosso do Sul. Eighteen species of social wasps were collected, by the methods of active searching and traps baited with honey and sardine. Eight species were classified as infrequent, five as very frequent, and five as of intermediate frequency. The community structure, as represented by species richness, showed a significant negative correlation with the Berger-Parker dominance index, and no sig- nificant correlation with the width of the fragments and with the structural complexity of the vegetation, suggesting that the community, in this case, must be structured by the tolerance of the species and not by the vegetation characteristics, which did not limit the dispersal of the social wasps. Keywords: Polistinae, species richness, dominance index. INTRODUCTION The term riparian forest (gallery forest; in Portuguese “mata ciliar”) is syn- onymous with the official nomenclature (IBGE 1992) of “seasonal semidecidu- ous alluvial forest”. In spite of their importance and although they are legally preserved in Brazil, as Areas of Permanent Preservation, these forests are under anthropogenic pressures, with conflicting interests for use and occupation of the land, which have led to their destruction along entire watercourses for 1Programa de Pós-graduação em Entomologia e Conservação da Biodiversidade, Universidade Federal da Grande Dourados. Rodovia Dourados/Itahum, Km 12, Caixa Postal 241, 79.804-970, Dourados- MS, Brazil airambio@yahoo.com.br; williamantonialli@yahoo.com.br. 2Laboratório de Ecologia, Centro Integrado de Análise e Monitoramento Ambiental, Universidade Estadual de Mato Grosso do Sul. Rodovia Dourados/Itahum, Km 12, Caixa Postal 351, 79.804-970, Dourados-MS, Brazil. 756 Sociobiolog y Vol. 59, No. 3, 2012 farming or logging (Vestena & Thomaz 2006). Reduction and destruction of riparian forests are harmful to the biota, because these systems form ecologi- cal corridors, act to maintain the microclimate and biodiversity, and provide habitat, shelter, food and water to the fauna (Kageyama et al. 2001). The family Vespidae contains approximately 4,600 species, with one extinct subfamily and six current monophyletic subfamilies (Carpenter & Rasnitsyn 1990): Euparagiinae, Masarinae, Eumeninae, Stenogastrinae, Vespinae and Polistinae. Social species occur in the last three subfamilies. These species share a series of characteristics, including cooperation in the care of the offspring until the emergence of the adult, gradual provision, reuse of the reproductive cells, nest sharing between different generations, trophallaxis between adults, and division of labor (Carpenter 1991). The only eusocial subfamily that occurs in Brazil is the Polistinae, repre- sented by the tribes Polistini, Mischocyttarini and Epiponini (Carpenter & Marques 2001). The Polistinae is a diverse group and it taxonomy is relatively well known, so that many species can be identified with precision through published keys (Carpenter & Marques 2001; Garcete-Barrett 1999; Richards 1978). Some species of wasps possess wide ecological valence; that is, they vary their habits of nest building as a function of the substrate and the environ- mental conditions (Marques et al. 1993; Santos & Gobbi 1998). Other species have relatively narrow ecological valence and only nest in sites with specific conditions (Santos et al. 2007; Santos et al. 2009; Silva-Pereira & Santos 2006), selected for the type and density of the vegetation, the arrangement and shapes of leaves, and other plant structures (Dejean et al. 1998; Diniz & Kitayama 1994; Santos & Gobbi 1998). A few recent studies have examined the community structure or the con- stancy of species of social wasps, in particular the work of Santos et al. (2007) in Atlantic Forest, restinga, and mangrove ecosystems, and of Silva-Pereira & Santos (2006) in montane savannah (Portuguese “campo rupestre”); however, published studies on this subject are still few. The present study evaluated the constancy of the species and the relationship of the structure of the community of polistine wasps to the size and structural complexity of the vegetation, and to the dominance index associated with different fragments of riparian forest. 757 Bomfim, M.G.C.P. & Antonialli, W.F.J. — Community Structure of Social Wasps MATERIAL AND METHODS Social wasps were collected in ten fragments of riparian forest near the municipality of Batayporã, Mato Grosso do Sul (22º18’00”S, 53º15’97”W). Point 1: (22°15’80”S, 53°11’21”W); point 2: (22º14’82”S, 53º12’73”W); point 3: (22°20’98”S, 53°20’53”W); point 4: (22º13’86”S, 53º03’86”W); point 5: (22º14’58”S, 53º09’98”W); point 6: (22º18’78”S, 53º14’11”W); point 7: (22º18’59”S, 53º17’61”W); point 8: (22º11’93”S, 53º10’61”W); point 9: (22º20’89”S, 53º15’38”W); and point 10: (22º19’47”S, 53º19’22”W). In each fragment, 2,000 m² of riparian forest was selected, for a total study area of 20,000 m². The climate of Mato Grosso do Sul is humid subtropical, with a warm rainy period from November through April, and a cooler dry period from May through October (Zavatini 1992). We carried out ten collections in 30 days of fieldwork, in the period from October 2008 through March 2009. The collections were made by the methods of active searching and baited traps. Active searching was carried out during the time of day when the wasps are most active, from 09:00 to 15:00 h (Andrade & Prezoto 2001; Elisei et al. 2005; Lima & Prezoto 2003). We used a liquid bait, composed of a solution of sucrose (1:5, commercial sugar: water) and 2 cm3 of salt for each liter of solution, sprayed on the vegetation; and captured the wasps with an entomological net (Noll & Gomes 2009). In each forest fragment, we walked parallel to the watercourse at different distances from it, for six hours, totaling 60 hours of fieldwork for this method. In each fragment, we installed 40 baited traps, 20 containing a mixture of honey and water, and 20 containing a mixture of sardines and water, in 2 liter plastic bottles with side openings, as described by Souza & Prezoto (2006). In each forest fragment, the traps were attached 1.50 m above the ground, every 10 m along a 200 m transect, parallel to and about 5 m distant from the stream, and were removed after one week (Elpino-Campos et al. 2007; Souza & Prezoto 2006). This constituted a sampling effort of 60 baited traps. The specimens collected were identified by dichotomous keys proposed by Carpenter & Marques (2001), Garcete-Barrett (1999) and Richards (1978) and by comparison with specimens of social wasps deposited in the Comparative Biolog y Laboratory of Paraná Federal University. Vouchers were deposited in the Museu de Entomologia of the Universidade Federal da Grande Dourados, UFGD. 758 Sociobiolog y Vol. 59, No. 3, 2012 Constancy was calculated by the frequency of occurrence of each species. Very frequent species were considered to be those that occurred in more than 50% of the fragments; of intermediate frequency, species that occurred in 25 to 50%; and as infrequent, species that were present in less than 25% of the fragments. To evaluate the existence of a correlation between dominance and the community structure, represented by the species richness, the Berger-Parker dominance index was calculated for each collection point. This index con- siders the highest ratio of the species with the largest number of individuals (Rodrigues 2007), expressing the dominance of one or more species in a com- munity, based on the importance value of each species. After the dominance index was calculated, an analysis of linear correlation was carried out, with a level of significance (α) of 0.05 between these parameters. The widths of the fragments of riparian forest, including both banks of the watercourse, were measured with the aid of a measuring tape. The structural complexity of the vegetation was evaluated by counting trees, saplings, shrubs, lianas, seedlings, and the thickness of the leaf litter. The counts were made in a sample plot of 4 m², at each collection point. To obtain the vectors associated with these variables, a Principal Components Analysis was used (PCA). To give the same importance to these variables, the value of each was divided by the square root of the total sum of squares (Vieira et al. 2008). To evaluate if there was a significant correlation between the structure of the community and the width of the fragments, and between the structure of the community and the structural complexity of the vegetation, the Linear Correlation Analysis was used, with a level of significance (α) of 0.05. RESULTS AND DISCUSSION We collected 18 species of social wasps (Table 1) belonging to six genera, with representatives of the tribes Polistini, Mischocyttarini and Epiponini. Tribe Epiponini was most important, with 10 species (56%), followed by Polistini with 7 (39%), and Mischocyttarini with only 1 (5%). Of the total of 529 individual wasps caught, 456 (86%) were members of the tribe Epiponini, 46 (9%) Polistini, and only 27 (5%) Mischocyttarini. The predominance of epiponine wasps can be explained by the large numbers of individuals found in their colonies, in particular, the genus Agelaia, which in 759 Bomfim, M.G.C.P. & Antonialli, W.F.J. — Community Structure of Social Wasps some species such as Agelaia vicina (Saussure 1854) may have up to a million adults in a single colony (Zucchi et al. 1995). Eight species (44%) were classified as infrequent, five (28%) as intermedi- ate, and five (28%) as very frequent (Table 1). The infrequent species were captured in less than 25% of the fragments. This may be related to the wide radius of action of the wasps during foraging. For example, Polistes versicolor (Olivier 1791) shows a 200 m effective radius of action (Gobbi 1978), and Polistes simillimus (Zikán 1951) a 150 m radius of action (Prezoto & Gobbi 2005). This capacity of movement results in many captures of infrequent species in locations other than their permanent habitat. Diniz & Kitayama (1998) and Silva-Pereira & Santos (2006) observed that some wasps can construct their nests in one environment and forage in locations distant from that environment. Considering that the environment Table 1. Constancy of the species of social wasps, as a function of the relative frequency of occurrence in the fragments of riparian forest in Batayporã, Mato Grosso do Sul state, Brazil. Species Frequency % Constancy (C) 1 Apoica pallens (Fabricius) 30% Intermediate Frequency 2 Agelaia pallipes (Olivier) 70% Very Frequent 3 Brachygastra augusti de Saussure 30% Intermediate Frequency 4 Polybia jurinei de Saussure 10% Infrequent 5 Polybia ignobilis (Haliday) 50% Intermediate Frequency 6 Polybia sericea (Olivier) 30% Intermediate Frequency 7 Polybia chrysothorax (Lichtenstein) 20% Infrequent 8 Polybia paulista (H. Von Ihering ) 70% Very Frequent 9 Polybia ruficeps Schrottky 20% Infrequent 10 Polybia occidentalis (Olivier) 70% Very Frequent 11 Polistes subsericeus de Saussure 60% Very Frequent 12 Polistes versicolor (Olivier) 40% Intermediate Frequency 13 Polistes simillimus Zikán 10% Infrequent 14 Polistes brevifissus Richards 20% Infrequent 15 Polistes billardieri (Fabricius) 20% Infrequent 16 Polistes cinerascens de Saussure 10% Infrequent 17 Polistes geminatus (Fox) 10% Infrequent 18 Mischocyttarus drewseni de Saussure 60% Very Frequent 760 Sociobiolog y Vol. 59, No. 3, 2012 that surrounds the fragments studied here consists of Cerrado, the riparian forest may represent only part of the foraging area for those species that use the Cerrado as a permanent habitat. Supporting this hypothesis, Polistes simillimus, for example, prefers to nest in dry habitats, and Polistes geminatus (Fox 1898), Polistes billardieri (Fabricius 1804) and Polybia chrysothorax (Lichtenstein 1796) prefer the Cer- rado (Garcete-Barrett 1999). Therefore, riparian forest would be a transitory environment for many of these species. Santos et al. (2007) also found the species Polistes carnifex (Fabricius 1775) and Synoeca cyanea (Fabricius 1775) foraging in mangrove areas, apparently a transitory environment for them, but their nests are restricted to the Restinga and Atlantic Forest. Santos et al. (2009) also observed the occurrence of Protonectarrina sylveirae (de Saussure 1854), Parachartergus pseudoapicalis (Willink 1859) and Synoeca cyanea in agricultural systems other than their nest sites. The species with intermediate frequency can be considered as tolerant, changing their nest building habitats according to ambient conditions and the available substrata. Apoica pallens (Fabricius 1804), Polybia ignobilis (Haliday 1836) and Polybia sericea (Olivier 1791) are known to be toler- ant (Santos 2000) and both Brachygastra augusti (de Saussure 1834) and Polistes versicolor (Olivier 1791) can also be found in forests and the Cerrado (Garcete-Barrett 1999). In contrast, Agelaia pallipes (Olivier 1791), Polybia paulista (Von Ihering 1896), Polybia occidentalis (Olivier 1791), Polistes subsericeus (Saussure 1854) and Mischocyttarus drewseni were very frequent in this study, probably because of their numerous colonies (Zucchi et al. 1995), or because they found in the riparian forest fragments a more favorable environment than the Cerrado. In particular, M. drewseni shows a clear preference for more humid environ- ments (Garcete-Barrett 1999). The width of the fragments of riparian forest varied at the different collec- tion points, from 26 to 650 m (Table 2). No significant correlation between the width and the community structure in the fragments, represented by species richness, was found (r = 0.0476; t = 0.1347; p= 0.8962 and GL= 8). It can be suggested that the fragments of riparian forest do not represent islands for the polistines, and that the surrounding areas of Cerrado do not represent a barrier to the dispersal of these species. 761 Bomfim, M.G.C.P. & Antonialli, W.F.J. — Community Structure of Social Wasps The variation in the structural complexity of the vegetation among the collection points can be represented by the first two axes of a Principal Com- ponents Analysis (Table 2). These axes accounted for 70.57% of the variance (eigenvalues 2.687 for axis 1 and 1.548 for axis 2) of the original data for the numbers of trees, shrubs, lianas, seedlings, and thickness of the leaf litter; the first axis (PCA 1) explained 44.77% of this variance. For correlation analysis between the variable structural complexity of the vegetation (represented by PCA axes 1 and 2) and the community structure, represented by the species richness, significant correlations between PCA axes 1 (r = 0.1114; t = 0.3171; p = 0.7593 and GL = 8) and 2 (r = -0.0601; t = -0.1703; p = 0.8690 and GL = 8) with the community structure were also not found. Therefore, the results demonstrate that the occurrence of species of polistine wasps in these fragments is not correlated with the vegetation complexity. This result differs from the data of Santos et al. (2007), who found a direct correlation between the structural complexity of vegetation and the diversity of wasp species. Table 2. Dominance index, species richness, width of the fragments of riparian forest, and values of axes 1 and 2 of the Principal Components Analysis (PCA) representing the vegetation complexity of the sampling points. Collection Points Berger-Parker Dominance Dominant Species Species Richness Width (m) Vegetation Complexity PCA 1 PCA 2 1 0.63 Polistes versicolor 6 300 -16.290 21.122 2 0.86 Polybia paulista and Polybia occidentalis 3 26 -0.7003 -17.453 3 0.57 Apoica pallipes 8 650 42.221 0.4993 4 0.73 Polybia occidentalis and Agelaia pallipes 6 520 0.0288 0.4091 5 0.52 Agelaia pallipes 8 30 0.1297 -0.7871 6 0.53 Polybia paulista and Polybia sericea 8 55 -0.6588 -18.211 7 0.98 Agelaia pallipes 3 180 -0.2916 13.790 8 0.49 Polybia paulista 11 50 -12.265 0.2321 9 0.75 Mischocyttarus drewseni 5 100 -0.6985 0.0544 10 0.54 Agelaia pallipes 5 150 0.8240 -0.3326 762 Sociobiolog y Vol. 59, No. 3, 2012 However, although the richness in a community can be influenced by the number of niches, which reflects the structural heterogeneity of the environ- ment, it also can be partly determined by the tolerance of the species to the physical conditions (basic niche) and by interactions with other species (actual niche) (Giller 1984; Santos et al. 2007). Tolerant species also possess wide ecological valence (Marques & Carvalho 1993; Santos & Gobbi 1998). The correlation analysis between the community structure, represented by species richness, and the Berger-Parker dominance index indicated a signifi- cant negative correlation (r = -0.8375; t = -4.3358; p = 0.0025 and GL = 8, Fig. 1); the richness decreased as the dominance increased. In particular, the analysis indicated the dominance of Polybia paulista (d= 0.49) at point 8, the co-dominance of Polybia paulista (d= 0.57) and Polybia occidentalis (d= Figure 1. Correlation between species richness and the Berger-Parker dominance index (α = 0.05; GL = 8). The numbers beside the points indicate the collection localities. 763 Bomfim, M.G.C.P. & Antonialli, W.F.J. — Community Structure of Social Wasps 0.29) at point 2, the co-dominance of Polybia paulista (d= 0.29) and Polybia sericea (d= 0.24) at point 6, the co-dominance of Polybia occidentalis (d= 0.32) and Agelaia pallipes (d= 0.41) at point 4, the dominance of Agelaia pallipes at points 3, 5, 7 and 10, of Polistes versicolor at point 1, and of Mischocyttarus drewseni at point 9. ACKNOWLEDGMENTS We thank CNPq (133014/2009-6) for the Master’s Degree fellowship granted to the first author, and WFAJ also acknowledges research support from this agency. We are grateful to Bolivar R. Garcete-Barrett of the Universidade Federal do Paraná, Curitiba, Brazil, for confirming species identifications. REFERENCES Andrade, F.R. & F. Prezoto. 2001. Horários de atividade forrageadora e material coletado por Polistes ferreri Saussure, 1853 (Hymenoptera, Vespidae), nas diferentes fases de seu ciclo biológico. Revista Brasileira de Zoociências 3: 117-128. Carpenter, J.M. 1991. Phylogenetic relationships and the origin of social behavior in the Vespidae. p. 7-32. In: K.G. Ross & R.W. Matthews. The social biolog y of wasps. Ithaca, Cornell University Press. 678p. Carpenter, J.M. & A.P. Rasnitsyn. 1990. Mesozoic Vespidae. Psyche 97: 1-20. Carpenter, J.M. & O.M. Marques. 2001. Contribuição ao estudo dos vespídeos do Brasil (Insecta, Hymenoptera, Vespoidea, Vespidae) [CD-ROM]. Cruz das Almas – BA, Brasil. Universidade Federal da Bahia, Escola de Agronomia, Departamento de Fitotecnia / Mestrado em Ciências Agrárias. Série Publicações Digitais, 2. Dejean, A.; B. Corbara & J.M. Carpenter. 1998. Nesting site selection by wasps in the Guaianese Rain Forest. Insects Sociaux 45: 33-41. Diniz, I.R. & K. Kitayama. 1994. Colony densities and preferences for nest habitats of some wasps in Mato Grosso State, Brazil (Hymenoptera: Vespidae). Journal of Hymenoptera Research 3: 133-143. Diniz, I.R. & K. Kitayama. 1998. Seasonality of vespid species (Hymenoptera: Vespidae) in a central Brazilian cerrado. Revista de Biologia Tropical. 46: 109-114. Elisei, T.; C. Ribeiro-Júnior; D.L. Guimarães & F. Prezoto. 2005. Foraging activity and nesting of swarm-founding wasp Synoeca cyanea (Fabricius, 1775) (Hymenoptera, Vespidae, Epiponini). Sociobiolog y 46: 317-327. Elpino-Campos, A.; K. Del-Claro & F. Prezoto. 2007. Diversity of social wasps (Hymenoptera: Vespidae) in Cerrado fragments of Uberlândia, Minas Gerais State, Brazil. Neotropical Entomolog y 36: 685-692. IBGE – Fundação Instituto Brasileiro de Geografia e Estatística. 1992. Manual técnico da vegetação brasileira. Rio de Janeiro, IBGE, 92p. 764 Sociobiolog y Vol. 59, No. 3, 2012 Garcete-Barrett, B.R. 1999. Guía ilustrada de las avispas sociales del Paraguay (Hymenoptera: Vespidae: Polistinae). London, The Natural History Museum, 56p. Gobbi, N. 1978. Determinação do raio de vôo de operárias de P. versicolor (Hymenoptera, Vespidae). Ciência e Cultura 30: 364-365. Guiller, P.S. 1984. Community structure and the niche. London, Chapman and Hall, 176p. Lima, M.A.P. & F. Prezoto. 2003. Foraging activity rhythm in the neotropical swarm-founding wasp Polybia platycephala sylvestris (Hymenoptera: Vespidae) in different seasons of the year. Sociobiolog y 42: 745-752. Kageyama, P.Y.; F.B. Gandara; R.E. Oliveira & L.F.D. Moraes. 2001. Restauração da mata ciliar – Manual para recuperação de áreas ciliares e microbacias. Rio de Janeiro, Semads, 104p. Marques, O.M.; C.A.L. Carvalho & J.M. Costa. 1993. Levantamento das espécies de vespas sociais (Hymenoptera, Vespidae) no município de Cruz das Almas, Estado da Bahia. Insecta 2: 1-9. Noll, F.B. & B. Gomes. 2009. An improved bait method for collecting Hymenoptera, especially social wasps (Vespidae: Polistinae). Neotropical Entomolog y 38: 477-481. Prezoto, F. & N. Gobbi. 2005. Fligth range extension in Polistes simillimus Zikán, 1951 (Hymenoptera, Vespidae). Brazilian Archives of Biolog y and Tecnolog y 48: 947-950. Richards, O.W. 1978. The social wasps of Americas excluding the Vespinae. London, British the Natural History Museum, 580p. Rodrigues, W.C. 2007. DivEs – Diversidade de espécies – guia do usuário. Seropédica: Entomologistas do Brasil. 9 p. http://ebras.bio.br/dives. Acesso em janeiro de 2009. Santos, G.M.M. 2000. Comunidades de vespas sociais (Hymenoptera - Polistinae) em três ecossistemas do estado da Bahia, com ênfase na estrutura da guilda de vespas visitantes de flores de Caatinga. Tese de doutorado, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto/USP, 129p. Santos, G.M.M. & N. Gobbi. 1998. Nesting habitats and colonial productivity of Polistes canadensis canadensis (L.) (Hymenoptera – Vespidae) in a caatinga area, Bahia State – Brazil. Journal of Advanced Zoolog y 19: 63-69. Santos, G.M.M.; C.C.B. Filho; J.J. Resende; J.D. Cruz & O.M. Marques. 2007. Diversity and community structures of social wasps (Hymenoptera: Vespidae) in three ecosystems in Itaparica Island, Bahia State, Brazil. Neotropical Entomolog y 36: 180-185. Santos, G.M.M.; J.D. Cruz; O.M. Marques & N. Gobbi. 2009. Diversidade de vespas sociais (Hymenoptera: Vespidae) em áreas de Cerrado na Bahia. Neotropical Entomolog y 38: 317-320. Silva-Pereira, V. & G.M.M. Santos. 2006. Diversity in bee (Hymenoptera: Apoidea) and social wasp (Hymenoptera: Vespidae, Polistinae) community in “campos rupestres”, Bahia, Brazil. Neotropical Entomolog y 35:163-174. Souza, M.M & F. Prezoto. 2006. Diversity of social wasps (Hymenoptera, Vepidae) in Semideciduous Forest and Cerrado (Savanna) regions in Brazil. Sociobiolog y 47: 135 – 147. 765 Bomfim, M.G.C.P. & Antonialli, W.F.J. — Community Structure of Social Wasps Vestena, L.R. & E.L. Thomaz. 2006. Avaliação de conflitos entre áreas de preservação permanente, associadas aos cursos fluviais e uso da terra na bacia do Rio das Pedras, Guarapuava – PR. Ambiência 2: 73-85. Vieira, L.; F.S. Lopes; W.D. Fernandes & J. Raizer. 2008. Comunidade de Carabidae (Coleoptera) em manchas florestais no Pantanal, Mato Grosso do Sul, Brasil. Iheringia 98: 317-324. Zavatini, J.A. 1992. Dinâmica climática no Mato Grosso do Sul. Geografia 17: 65-91. Zucchi, R.; S.F. Sakagami; F.B. Noll; M.R. Mechi; S. Mateus; M.V. Baio & S.N. Shima. 1995. Agelaia vicina, a swarm-founding polistine with the largest colony size among wasps and bees (Hymenoptera: Vespidae). Journal of the New York Entomological Society 103: 129-1.