Sex Ratio, Sexual Dimorphism, and Wing Geometric Morphometrics in Species of Trypoxylon Latreille, 1796 (Hymenoptera: Crabronidae).

Studying the nesting biology of wasp and bee species provides valuable insights into the ecology and evolution of these insects, shedding light on their ecological significance and aiding in their conservation efforts. Trypoxylon Latreille, 1796 is a genus of spider-hunting wasps that provisions their brood with paralyzed preys. This study focuses on aspects of nesting biology of Trypoxylon (Trypargilum) species such as sex ratio, sexual dimorphism, and morphometric variation at both inter- and intraspecific levels. The secondary sex ratio (SR) exhibited variation among species and populations. Males predominantly emerged from the first brood cells and from trap nests with smaller diameters. In comparison, females showed significantly larger body mass and linear wing measurements than males. Procrustes ANOVA values for centroid size (CS) and wing shape (SH) indicated significant differences in both wing size and shape among the five analyzed Trypoxylon species. Sexual dimorphism indices (SDI) derived from centroid size were found to be similar to those obtained from linear measurements, while SDI values based on body mass were significantly higher. Nests containing a greater number of cells tended to produce a larger number of higher-quality males and females. This observation, along with the lower coefficient of variation for female body size and high heritability, suggests that this trait may be subject to natural selection. Further studies that estimate the size of parents and their respective offspring are necessary to confirm the fitness advantage associated with larger female sizes in Trypoxylon species.

Overlap of Ecological Niche Breadth of Euglossa cordata and Eulaema nigrita (Hymenoptera, Apidae, Euglossini) Accessed by Pollen Loads and Species Distribution Modeling.

Urban areas can serve as biodiversity refuges for pollinators because of the high diversity of available floral and nesting resources. However, it remains unclear what plant species commonly used for urban landscaping provide floral resources that pollinators actively use. Here, we integrate data from the pollen and species distribution models of two abundant euglossine bees-the large-bodied Eulaema nigrita (Lepeletier, 1841) and the small-bodied Euglossa cordata (Linnaeus, 1758)-in urban areas to investigate their overlap in diet breadth and distribution. We hypothesized that because bees with larger body sizes tend to have larger foraging areas, large-bodied bees would have a wider diet breath than small-bodied bees. Contrary to our hypothesis, we found that Eg. cordata has a wider diet breadth than El. nigrita with the former species showing higher diversity of pollen types collected (per pollen load and on average across pollen loads). Pollen grains from Solanum paniculatum and Tradescantia zebrina represented 63% of the diet of Eg. cordata, whereas pollen from S. paniculatum and Psidium guajava represented 87% of the diet of El. nigrita. After overlaying the distribution of both bee species and the three most important pollen resources, the distribution models revealed that these three plant species can co-occur with both euglossine bees throughout a large portion of eastern Brazil near the coast. Thus, we conclude S. paniculatum, T. zebrina, and P. guajava should be considered key plants for the maintenance of these two urban euglossine bee species. The results of this study provide important information for urban landscaping programs that aim to protect and preserve pollinators.

Pleistocene climate changes shaped the population structure of Partamona seridoensis (Apidae, Meliponini), an endemic stingless bee from the Neotropical dry forest.

Partamona seridoensis is an endemic stingless bee from the Caatinga, a Neotropical dry forest in northeastern Brazil. Like other stingless bees, this species plays an important ecological role as a pollinator. The aim of the present study was to investigate the genetic structure and evolutionary history of P. seridoensis across its current geographic range. Workers from 84 nests from 17 localities were analyzed for COI and Cytb genic regions. The population structure tests (Bayesian phylogenetic inference, AMOVA and haplotype network) consistently characterized two haplogroups (northwestern and eastern), with little gene flow between them, generating a high differentiation between them as well as among the populations within each haplogroup. The Mantel test revealed no isolation by distance. No evidence of a potential geographic barrier in the present that could explain the diversification between the P. seridoensis haplogroups was found. However, Pleistocene climatic changes may explain this differentiation, since the initial time for the P. seridoensis lineages diversification took place during the mid-Pleistocene, specifically the interglacial period, when the biota is presumed to have been more associated with dry conditions and had more restricted, fragmented geographical distribution. This event may have driven diversification by isolating the two haplogroups. Otherwise, the climatic changes in the late Pleistocene must not have drastically affected the population dynamics of P. seridoensis, since the Bayesian Skyline Plot did not reveal any substantial fluctuation in effective population size in either haplogroup. Considering its importance and the fact that it is an endemic bee from a very threatened Neotropical dry forest, the results herein could be useful to the development of conservation strategies for P. seridoensis.

Phylogeography of Partamona rustica (Hymenoptera, Apidae), an Endemic Stingless Bee from the Neotropical Dry Forest Diagonal.

The South America encompasses the highest levels of biodiversity found anywhere in the world and its rich biota is distributed among many different biogeographical regions. However, many regions of South America are still poorly studied, including its xeric environments, such as the threatened Caatinga and Cerrado phytogeographical domains. In particular, the effects of Quaternary climatic events on the demography of endemic species from xeric habitats are poorly understood. The present study uses an integrative approach to reconstruct the evolutionary history of Partamona rustica, an endemic stingless bee from dry forest diagonal in Brazil, in a spatial-temporal framework. In this sense, we sequenced four mitochondrial genes and genotyped eight microsatellite loci. Our results identified two population groups: one to the west and the other to the east of the São Francisco River Valley (SFRV). These groups split in the late Pleistocene, and the Approximate Bayesian Computation approach and phylogenetic reconstruction indicated that P. rustica originated in the west of the SFRV, subsequently colonising eastern region. Our tests of migration detected reduced gene flow between these groups. Finally, our results also indicated that the inferences both from the genetic data analyses and from the spatial distribution modelling are compatible with historical demographic stability.

Molecular phylogeny and historical biogeography of the neotropical swarm-founding social wasp genus Synoeca (Hymenoptera: Vespidae).

The Neotropical Region harbors high biodiversity and many studies on mammals, reptiles, amphibians and avifauna have investigated the causes for this pattern. However, there is a paucity of such studies that focus on Neotropical insect groups. Synoeca de Saussure, 1852 is a Neotropical swarm-founding social wasp genus with five described species that is broadly and conspicuously distributed throughout the Neotropics. Here, we infer the phylogenetic relationships, diversification times, and historical biogeography of Synoeca species. We also investigate samples of the disjoint populations of S. septentrionalis that occur in both northwestern parts of South America through Central American and the Brazilian Atlantic rainforests. Our results showed that the interspecific relationships for Synoeca could be described as follows: (S. chalibea + S. virginea) + (S. cyanea + (S. septentrionalis/S. surinama)). Notably, samples of S. septentrionalis and S. surinama collected in the Atlantic Forest were interrelated and may be the result of incomplete lineage sorting and/or mitochondrial introgression among them. Our Bayesian divergence dating analysis revealed recent Plio-Pleistocene diversification in Synoeca. Moreover, our biogeographical analysis suggested an Amazonian origin of Synoeca, with three main dispersal events subsequently occurring during the Plio-Pleistocene.

Genetic differentiation of the Euglossini (Hymenoptera, Apidae) populations on a mainland coastal plain and an island in southeastern Brazil.

Euglossini bees are among the main pollinators of plant species in tropical and subtropical forests in Central and South America. These bees are known as long-distance pollinators due to their exceptional flight performance. Here we assessed through microsatellite loci the gene variation and genetic differentiation between populations of four abundant Euglossini species populations sampled in two areas, Picinguaba (mainland) and Anchieta Island, Ubatuba, São Paulo State, southeastern Brazil. There was no significant genetic differentiation between the island and mainland samples of Euglossa cordata (Fst = 0.008, P = 0.60), Eulaema cingulata (Fst = 0.029, P = 0.29) and Eulaema nigrita (Fst = 0.062, P = 0.38), but a significant gene differentiation between mainland and island samples of Euglossa stellfeldi (Fst = 0.028, P = 0.016) was detected. As expected, our results showed that the water body that separates the island from the mainland does not constitute a geographic barrier for these Euglossini bees. The absence of populational structuring of three out the four species studied corroborates previous reports on those bees, characterized by large populations, with high gene diversity and gene flow and very low levels of diploid males. But the Eg. stellfeldi results clearly point that dispersal ability is not similar to all euglossine bees, what requires the development of different conservationist strategies to the Euglossini species.

Gene variation, population differentiation, and sociogenetic structure of nests of Partamona seridoensis (Hymenoptera: Apidae, Meliponini).

Gene variation and the differentiation of two populations of Partamona seridoensis (Hymenoptera: Apidae: Meliponini) from the Caatinga biome, a semiarid ecosystem unique to Brazil, were estimated through allozymic and microsatellite analyses. These populations exhibited similar low degrees of enzyme gene variation. Observed genotype frequencies at the allozyme and microsatellite loci were in accordance with Hardy-Weinberg equilibrium in the two populations. Both markers demonstrated that the two populations are not genetically homogeneous and must be considered distinct populations. The occurrence of private alleles at the allozyme and microsatellite loci corroborates this differentiation, sustaining the hypothesis of a low level of interpopulation gene flow. The phenotypic segregations clearly demonstrated that the progeny inside each nest were the result of mating between the queen of the colony and only one male.

Sociogenetic structure of Polistes (Aphanilopterus) versicolor Olivier, 1791 colonies (Hymenoptera, Vespidae, Polistini).

The observation of two distinct, well-defined oviposition areas in nests of the primitively eusocial wasp Polistes versicolor suggests the presence of multiple egg-layers and territorial behaviors. Electrophoretic analysis of enzyme loci in pupae from 35 colonies revealed an average observed heterozygosity of 0.10 and the existence of private polymorphisms, thereby indicating a low dispersion in this species. No evidence of diploid males was found. Phenotypic segregation analysis revealed the presence of more than one egg-laying female in 15 out of 35 colonies, as well as spatially preferential oviposition in 2 out of 13 nests, with distinct oviposition areas. Genetic relatedness estimates for brood were lower than expected for haplodiploid species under monogynous conditions (r = 0.75 for female broods and r = 0.5 for male) in 4 of those 13 nests, thereby inferring complex sociogenetic structuring in Polistes versicolor colonies.

Sociogenetic structure of Polistes (Aphanilopterus) versicolor Olivier, 1791 colonies (Hymenoptera, Vespidae, Polistini)

The observation of two distinct, well-defined oviposition areas in nests of the primitively eusocial wasp Polistes versicolor suggests the presence of multiple egg-layers and territorial behaviors. Electrophoretic analysis of enzyme loci in pupae from 35 colonies revealed an average observed heterozygosity of 0.10 and the existence of private polymorphisms, thereby indicating a low dispersion in this species. No evidence of diploid males was found. Phenotypic segregation analysis revealed the presence of more than one egg-laying female in 15 out of 35 colonies, as well as spatially preferential oviposition in 2 out of 13 nests, with distinct oviposition areas. Genetic relatedness estimates for brood were lower than expected for haplodiploid species under monogynous conditions (r = 0.75 for female broods and r = 0.5 for male) in 4 of those 13 nests, thereby inferring complex sociogenetic structuring in Polistes versicolor colonies.

Genetic structure of drone congregation areas of Africanized honeybees in southern Brazil.

As yet, certain aspects of the Africanization process are not well understood, for example, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. Drone congregation areas (DCAs) are the ideal place to study honeybee reproduction under natural conditions since hundreds of drones from various colonies gather together in the same geographical area for mating. In the present study, we assessed the genetic structure of seven drone congregations and four commercial European-derived and Africanized apiaries in southern Brazil, employing seven microsatellite loci for this purpose. We also estimated the number of mother-colonies that drones of a specific DCA originated from. Pairwise comparison failed to reveal any population sub-structuring among the DCAs, thus indicating low mutual genetic differentiation. We also observed high genetic similarity between colonies of commercial apiaries and DCAs, besides a slight contribution from a European-derived apiary to a DCA formed nearby. Africanized DCAs seem to have a somewhat different genetic structure when compared to the European.

Ocupação diferencial do habitat por vespas do gênero Trypoxylon (Trypargilum) Latreille (Hymenoptera, Crabronidae) / Differential occupation of the habitat by Trypoxylon (Trypargilum) Latreille wasps (Hymenoptera, Crabronidae)

Vespas do gênero Trypoxylon apresentam comportamento solitário e aprovisionam seus ninhos de forma massiva com aranhas paralisadas. Algumas espécies utilizam cavidades preexistentes para nidificação, o que facilita sua amostragem e estudo. Neste trabalho, dados sobre a biologia de nidificação de quatro espécies de Trypoxylon (Trypargilum) - T. rogenhoferi, T. lactitarse, T. aurifrons e T. nitidum - são apresentados. As espécies foram amostradas por meio de ninhos-armadilha durante três anos em Araras e dois anos em Rifaina e São Carlos (São Paulo). As localidades de estudo foram subdivididas em sítios de amostragem. Foram obtidos 2.698 ninhos de himenópteros solitários, dos quais 2.268 foram fundados por espécies de Trypoxylon. Intensa atividade de nidificação foi observada principalmente na estação quente e chuvosa (outubro-março). Os ninhos-armadilha utilizados para nidificação pelas diferentes espécies apresentaram dimensões significativamente diferentes. A família de aranhas mais utilizada para aprovisionamento foi Araneidae; no entanto, as espécies de vespas diferiram quanto às espécies forrageadas. O principal parasitóide das quatro espécies foi Melittobia, mas indivíduos das famílias Chrysididae, Ichneumonidae, Chalcididae e Sarcophagidae também foram verificados. Observou-se que as espécies de Trypoxylon coexistem temporalmente e que nas três localidades cada espécie nidificou com maior freqüência em um sítio particular, sugerindo uma ocupação diferencial do habitat. A partição do habitat aparentemente homogêneo pode ser resultado de "competição aparente" mediada por inimigos naturais comuns.

Wasps of the genus Trypoxylon are solitary and females mass-provision their nests with paralyzed spiders. Some species use successfully trap-nests for nesting foundation, making easier their sampling and study. This paper reports data about nesting biology of four species of Trypoxylon (Trypargilum) - T. rogenhoferi, T. lactitarse, T. aurifrons and T. nitidum. These species were sampled by trap-nests during three years in Araras and two years in São Carlos and Rifaina (São Paulo). These areas were subdivided into sampling sites. A total of 2,698 nests of solitary hymenopterans were collected and most of them (2,268) were founded by Trypoxylon species. Nesting activity was higher in the warm, rainy season (October-March). The trap-nests used by the different species showed significantly different dimensions. Araneidae was the spider family mainly used for provision, but a species-specific provisioning was observed. The most important parasitoid of the four species was Melittobia, but adult chrysidids, ichneumonids, chalcidids and sarcophagids also attacked their nests. In the three areas, the different species of Trypoxylon coexist temporally but each of them built their nests frequently in a specific site. This result may suggest differential occupation of the habitat. This habitat partition of an apparently homogeneous area may be a result of an "apparent competition" shaped by shared natural enemies.

Genetic structure of drone congregation areas of Africanized honeybees in southern Brazil

As yet, certain aspects of the Africanization process are not well understood, for example, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. Drone congregation areas (DCAs) are the ideal place to study honeybee reproduction under natural conditions since hundreds of drones from various colonies gather together in the same geographical area for mating. In the present study, we assessed the genetic structure of seven drone congregations and four commercial European-derived and Africanized apiaries in southern Brazil, employing seven microsatellite loci for this purpose. We also estimated the number of mother-colonies that drones of a specific DCA originated from. Pairwise comparison failed to reveal any population sub-structuring among the DCAs, thus indicating low mutual genetic differentiation. We also observed high genetic similarity between colonies of commercial apiaries and DCAs, besides a slight contribution from a European-derived apiary to a DCA formed nearby. Africanized DCAs seem to have a somewhat different genetic structure when compared to the European.

Nesting biology of the trap-nesting Neotropical wasp Trypoxylo n(Trypargilum) aurifrons Shuckard (Hymenoptera, Crabronidae)

The present study was carried out in three localities of the state of São Paulo, Brazil: Araras (Dec/03-Dec/06), São Carlos (Nov/04-Nov/06) and Rifaina (Jul/04-Dec/06). Trap-nests were distributed among sites in the sampling areas and were collected every 35 days. Data from 295 nests indicate that T. aurifrons is a multivoltine species, with higher rates of nest building and cell production in the warm, rainy season. The trap-nests used by the females ranged from 117 to 467 mm in length and 3.1 to 16.6 mm in diameter. All nests showed deep plugs and a vestibular cell was found in 37 percent of the complete nests. The number of cells per nest ranged from one to 12. Females were larger than males, emerged from longer cells and their cocoons were significantly larger. A secondary 1:1 sex ratio was found in Araras and Rifaina. No correlation was observed between the diameter of the trap-nest and sex ratio. Males were usually oviposited in the first brood cells. Male and female developmental time from egg to adult was longer in the cold, dry season. Trypoxylon aurifrons provisioned their nests mainly with orb-spiders from the family Araneidae. The most important mortality factor was the death of immature forms, probably due to development failure. The most important parasitoid was Melittobia sp.

Este estudo foi realizado em três localidades do estado de São Paulo: Araras (dez/03-dez/06), São Carlos (nov/04-nov/06) e Rifaina (jul/04-dez/06). Ninhos-armadilhas foram distribuídos em diferentes sítios das áreas amostradas e coletados a cada 35 dias. Dados de 295 ninhos mostraram que T. aurifrons é uma espécie multivoltina, com maiores taxas de nidificação e produção de células na estação quente e chuvosa. Os ninhos-armadilhas utilizados pelas fêmeas variaram de 117 a 467 mm de comprimento e de 3,1 a 16,6 mm de diâmetro. Todos os ninhos apresentaram parede de fundo e célula vestibular foi constatada em 37 por cento dos ninhos completos. O número de células por ninho variou de um a 12. Fêmeas emergiram de células e pupários maiores, sendo significantemente maiores que os machos. Razão sexual secundária igual a 1:1 foi observada em Araras e Rifaina. Não foi encontrada correlação significativa entre a razão sexual e o diâmetro do tubo. Machos foram encontrados principalmente nas primeiras células de cria. O tempo de desenvolvimento ovo-adulto foi mais longo na estação fria e seca. Trypoxylon aurifrons aprovisionou seus ninhos principalmente com aranhas da família Araneidae. O principal fator de mortalidade foi a interrupção do desenvolvimento das formas imaturas e o parasitóide mais freqüentemente encontrado foi Melittobia sp.

Allozyme variation and sociogenetic structure of Polistes satan Bequaert 1940 colonies (Hymenoptera, Vespidae)

We collected 40 colonies of the wasp Polistes satan in November 1993 (Population A = 23 colonies) and October 1995 (Population B = 17 colonies) from the town of Delfinopólis in the Brazilian state of Minas Gerais. Pupae from these nests were used to assess allozyme variation and genetic relatedness among nestmates. Of the 24 gene loci sampled six showed allozyme polymorphism (Est-2, Pgm-1, 6Pgd, Hk-1, Idh and Pep-A) and all loci except Idh were at Hardy-Weinberg equilibrium. Populations A and B showed distinct intra-loci heterozygosities, but similar average heterozygosity over all loci. Significant inter-population differentiation (Fst = 0.051; p < 0.01) was detected, probably due to genetic drift driven by bottlenecking that occurred due to the first sampling. Mean intra-colony relatedness values between female broods (rA = 0,525 ± 0.063; rB = 0,456 ± 0.103) indicated that P. satan has a simple sociogenetic structure where one female takes on most of the reproductive tasks but, eventually, subordinates also reproduce in the colony.

Mortalidade de abelhas visitantes de flores de Caesalpinia peltophoroides Benth (Leguminosae) no estado de São Paulo, Brasil / Mortality of bees visiting Caesalpinia peltophoroides Benth (Leguminosae) flowers in the state of São Paulo, Brazil

É relatada a mortalidade de abelhas (213 fêmeas e 60 machos) pertencentes a 20 espécies ao visitarem as inflorescências de Caesalpinia peltophoroides. A presença presumida de um composto tóxico no néctar mostrou grande variação espacial e temporal. Arvores individuais produziram ou não mortalidade de abelhas em diferentes períodos de floração e árvores vizinhas mostraram efeitos distintos em cada floração. A toxicidade sobre as abelhas foi igualmente variável. A maior parte das abelhas morria logo após visitarem as flores; algumas mostravam sinais de narcose, morrendo em seguida; poucas, após um período de narcose, deixaram este estado e voaram. Utilizando o índice de desgaste alar foram observadas abelhas jovens (29 por cento), velhas (26 por cento) e de idade intermediária (45 por cento) (n = 227) entre as abelhas mortas. Se a presença do presumido composto tóxico afeta ou não o fitness da planta requer inicialmente a identificação de qual(is) fator(es) elicia(m) seu aparecimento. Uma vez que C. peltophoroides é amplamente utilizada em projetos paisagísticos urbanos, é necessário estimar o potencial efeito negativo sobre as comunidades de abelhas que vivem em áreas urbanas de diferentes regiões do Brasil. Até que este efeito seja conhecido, recomenda-se aos profissionais do planejamento urbano a não utilização paisagística da sibipiruna em nossas cidades.

It is reported the mortality of bees (213 females and 60 males) belonging to 20 species when visiting the inflorescences of Caesalpinia peltophoroides. The presumed presence of a toxic compound in the nectar showed considerable spatial and temporal variation. Sibipiruna trees may or may not kill bees during different flowering periods and neighboring trees showed distinct effects on bee mortality. The toxicity effect on bees was quite variable. Most of the bees died immediately after visiting some flowers; a few showed signals of narcosis, but after some time they came out of this state and flew away. Using a wing-wear index, 'young' (29 percent), 'old' (26 percent) and intermediate aged bees (45 percent) (n = 227) were observed among the dead insects. Determining whether the presence of a toxic nectar affects plant fitness requires the identification of this chemical and the knowledge of what factor or factors elicit its production. As C. peltophoroides is widely used in urban landscape projects, it is necessary to estimate the potencial negative effect on bee communities living in urban areas of Bazil. We recommend that urban planners avoid the use of sibipiruna trees for landscape purposes until the real mortality effect on bees is clarified.

Biologia, comportamento social e alocacão sexual de Digelasinus diversipes ( Kirby, 1882 ) ( Hymenoptera, Argidae ) / Biology, social behavior and sex - allocation of Digelasinus diversipes ( Kirby, 1882 ) ( Hymenoptera, Argidae )

São apresentados os resultados de um estudo de dois anos sobre o Symphyta neotropical Digelasinus diversipes. Esta espécie é univoltina e comum na Estacão Ecológica Jataí, uma reserva de Cerrado no Estado de São Paulo. As larvas alimentam-se gregariamente em Eugenia glazioviana (Myrtaceae) de novembro a abril. Associacões entre grupos de alimentacão foram freqüentes. Após o período de alimentacão, as larvas congregam-se e comunalmente constróem uma massa de casulos (105 casulos n 60DP; n = 25) aderida ao tronco da planta hospedeira, permanecendo em diapausa como prepupas até o início da estacão chuvosa, em outubro. O pico populacional foi observado em dezembro, quando 62 por cento (n = 2.967) dos adultos emergiram. Em condicões experimentais, foram observadas emergências das 6:30 às 15:00 h, mas 73,5 por cento (n = 223) dos adultos emergiram entre 9:00 e 12:00 h. Não foi observado, durante a emergência, sequenciamento sexual, mas em um agregado de casulos os machos podem emergir de 20 a 40 dias antes das fêmeas. Após a emergência os machos podem (1) dispersar-se (no início e final do período de emergência; outubro e novembro, janeiro e fevereiro, respectivamente) ou (2) permanecer sobre ou próximo ao agregado de casulos e copular com as fêmeas recém-emergidas (durante o pico de emergência, em dezembro). As cópulas duraram 4,28 minutos (n 3,4DP; n = 28). Ao longo do dia, os machos podem copular com diferentes fêmeas (1-8; n = 5); contudo, as fêmeas copularam apenas uma vez. Em média, as fêmeas emergem com 76 (n 21DP; n = 19) ovos maduros e todos eles são ovipositados de uma só vez sob uma única folha da planta hospedeira. A guarda dos ovos pelas fêmeas durou apenas 2 dias (n = 12) dos 30 necessários para sua incubacão. O repertório de comportamentos da fêmea contra potenciais inimigos foi menor do que o observado em outras espécies de Symphyta. Aparentemente, a fêmea induz um necrosamento do tecido foliar que cobre os ovos. Isto formaria uma protecão rígida para os ovos durante sua incubacão. Em D. diversipes, adultos de ambos os sexos não se alimentaram (condicão controlada) e tiveram vida curta (5,2 dias n 1,7DP; mínimo 1, máximo 11; n = 179). A razão sexual média...

Clinal variation and selection on MDH allozymes in honeybees in Chile.

Evidence of clinal variation and selection on Mdh-1 locus was observed in 27 samples from 22 sites in a 2800 km north-south transect across Chile. We found a negative correlation among F allele normalized frequency and mean temperature, and minimum temperature of January and July, as well as a positive correlation among S allele normalized frequency and annual mean, and minimum January temperatures. Our results lend weight to the idea that Chilean honeybee populations of colder areas have higher F allele frequencies, supporting previous claims that Mdh-1 allozymes of Apis mellifera are subject to temperature-mediated selection.

Populational genetic structure and sociogenetic structure of cocoon masses of Digelasinus diversipes (Kirby, 1882) (Hymenoptera: Symphyta: Argidae)

Gene variation and population genetic structure of the Neotropical sawfly Digelasinus diversipes were measured by allozyme analyses using starch gel electrophoresis. Cocoon masses were collected in Eugenia glazioviana (Myrtaceae) stems, in two areas of the "Estação Ecológica Jataí" (Luiz Antônio, SP, Brazil - 21°25' S, 47°50' W), in 2000 and 2001. The average heterozygosity observed in this species (Hobs = 0.094 ± 0.025) was not significantly different from other Symphyta groups; it was, however, significantly higher than in other Hymenoptera populations. No significant levels of inbreeding were found (F IS = 0.062; chi2 = 29.9; p > 0.05), but the population was subdivided (F ST = 0.070; chi2 = 458.9; p < 0.05), suggesting the absence of a significant gene flow among the samples studied, due to limited dispersion ability. The low relatedness coefficients found (ranging from 0.23 ± 0.09 to 0.44 ± 0.10) suggest that larvae from different ovipositions associate to construct the cocoon masses.

Alocação sexual e seleção sexo-dependente para tamanho de corpo em Trypoxylon rogenhoferi Kohl (Hymenoptera, Sphecidae) / Sex allocation and sex-dependent selection for body size in Trypoxylon rogenhoferi Kohl (Hymenoptera, Sphecidae)

Two populations of the wasp Trypoxylon rogenhoferi Kohl, 1884 from São Carlos and Luís Antônio, State of São Paulo, Brazil, were observed and sampled from May 1999 to February 2001 using trap-nests. This mass-provisioning wasp was used to test some aspects of optimal sex allocation theory. Both populations fit all the predictions of the models of Green and Brockmann and Grafen. Maternal provisions determined the size of each offspring, and females allocated well-stocked brood cells to daughters, the sex that benefits most being large. This strategy resulted in a difference in size between the sexes. In São Carlos, female weight at emergence was 1.18 times that of males, in Luís Antônio this value was 1.13. The brood cell volume was correlated with both wing length and weight at emergence in both sexes, and the chance that a given brood cell contained a male offspring decreased with increased brood cell volume. In T. rogenhoferi female body size was related to fitness. Larger females were able to collect more mass of spiders per day, the spiders they captured were heavier, and they provisioned more brood cells per day. They also produced larger daughters. For males, no relationship between body size and fitness was found, but the data were scarce. Since the patterns of provisioning were variable among different females in both study sites, it is possible that the females not follow a unique strategy for sex allocation. The sex ratio and/or investment ratio in the São Carlos population was female-biased and in Luís Antônio, male-biased. In spite of the influence of trap-nests diameters on male production in Luís Antônio, there is some evidence that in São Carlos population the local availability of prey and/or lower rate of parasitism may be major forces in determining the observed sex ratio, but further studies are necessary to verify such hypothesis.

Genetic structure of honeybee populations from southern Brazil and Uruguay

Apis mellifera scutellata was introduced to Brazil in 1956 and Africanized honeybee populations have now spread from Argentina to the southwestern United States. Temperate climatic restrictions seem to be a natural limit to Africanized honeybee expansion around parallels 35º to 40º SL. We used allozyme loci (Mdh-1 and Hk-1) and mtDNA haplotypes to characterize honeybee populations in southern Brazil and Uruguay and define a possible transition area between Africanized and European bees. Samples of 194 bee colonies were collected from ten localities between 30º-35º SL and 52º-59º WL. The mtDNA restriction patterns of these colonies were obtained through digestion of the mitochondrial genome by Eco RI, or by digestion by Bgl II and Xba I of the cytochrome B locus and the COI-COII intergenic region, respectively. The distribution limit of African bee colonies, i.e., those populations with only the African mtDNA haplotype and with a high proportion of African genes as shown by allozyme analysis, is located in northern Uruguay, with a hybridization zone located farther south in Uruguay. A gradual cline from north to south was observed, confirmed by mtDNA, racial admixture, and genetic distance analyses. No evidence of either gametic disequilibrium between nuclear markers or cytonuclear disequilibrium among the nuclear and mtDNA genotypes was detected, suggesting that the hybridization process has been completed