Phoretic mites (Acari: Chaetodactylidae) associated with the solitary bee Tetrapedia diversipes (Apidae: Tetrapediini)

Solitary bees of the genus Tetrapedia have a specific association with mites of the genus Roubikia (Chaetodactylidae). These mites are frequently found attached to active Tetrapedia bees. We quantified the number of mites on individuals of Tetrapedia diversipes Klug and examined the interaction between these species. Nests of T. diversipes were obtained from trap-nests placed in four localities in Sao Paulo, Brazil. The study lasted from March 2007 to February 2009. Out of a total of 650 nests with emergences, 118 were infested with mites (Roubikia sp.). From these nests, 176 individuals of T. diversipes emerged with mites on their bodies. Additionally, six individuals of Coelioxoides waltheriae, the specific kleptoparasitic bee to T. diversipes, emerged. Mites were attached mainly to the mesosoma. All nests infected with mites did not presented mortality of the immature. The mortality rate of nests was inversely related to the level of mite infestation, suggesting a mutualistic interaction in which mites may remove fungi from the nests, while the bees would provide the mites with transport, dispersal, and shelter.

Alloparental care in a solitary bee

Research into the evolutionary origins of sociality in insect colonies is changing emphasis from understanding how eusociality is maintained to how insects transition from solitary to social lifestyles. The pygmy carpenter bees (Ceratina spp.) offer an excellent model for investigating such factors as they have been historically thought of as solitary but have recently been shown to be socially polymorphic, which may indicate that they are currently in a transitive phase. By utilizing behavioural observation and experimental removal protocols, I show that extended parental care, as well as sibling care in Ceratina calcarata plays an important role in offspring development. I found, upon removal of the mother, that specifically produced ‘dwarf’ female offspring take over parental care roles in the nest. The existence of alloparental care and generational overlap suggests that although they are classified as solitary bees, C. calcarata possess the prerequisite behavioural repertoire for sociality.

Sublethal neonicotinoid insecticide exposure reduces solitary bee reproductive success

1. Pollinating insects provide crucial and economically important ecosystem services to crops and wild plants, but pollinators, particularly bees, are globally declining as a result of various driving factors, including the prevalent use of pesticides for crop protection. Sublethal pesticide exposure negatively impacts numerous pollinator lifehistory traits, but its influence on reproductive success remains largely unknown. Such information is pivotal, however, to our understanding of the long-term effects on population dynamics. 2 We investigated the influence of field-realistic trace residues of the routinely used neonicotinoid insecticides thiamethoxam and clothianidin in nectar substitutes on the entire life-time fitness performance of the red mason bee Osmia bicornis. 3 We show that chronic, dietary neonicotinoid exposure has severe detrimental effects on solitary bee reproductive output. Neonicotinoids did not affect adult bee mortality; however, monitoring of fully controlled experimental populations revealed that sublethal exposure resulted in almost 50% reduced total offspring production and a significantly male-biased offspring sex ratio. 4 Our data add to the accumulating evidence indicating that sublethal neonicotinoid effects on non-Apis pollinators are expressed most strongly in a rather complex, fitness-related context. Consequently, to fully mitigate long-term impacts on pollinator population dynamics, present pesticide risk assessments need to be expanded to include whole life-cycle fitness estimates, as demonstrated in the present study using O. bicornis as a model.

Sublethal neonicotinoid insecticide exposure reduces solitary bee reproductive success

1.Pollinating insects provide crucial and economically important ecosystem services to crops and wild plants, but pollinators, particularly bees, are globally declining as a result of various driving factors, including the prevalent use of pesticides for crop protection. Sublethal pesticide exposure negatively impacts numerous pollinator life-history traits, but its influence on reproductive success remains largely unknown. Such information is pivotal, however, to our understanding of the long-term effects on population dynamics. 2.We investigated the influence of field-realistic trace residues of the routinely used neonicotinoid insecticides thiamethoxam and clothianidin in nectar substitutes on the entire life-time fitness performance of the red mason bee Osmia bicornis. 3.We show that chronic, dietary neonicotinoid exposure has severe detrimental effects on solitary bee reproductive output. Neonicotinoids did not affect adult bee mortality; however, monitoring of fully controlled experimental populations revealed that sublethal exposure resulted in almost 50% reduced total offspring production and a significantly male-biased offspring sex ratio. 4.Our data add to the accumulating evidence indicating that sublethal neonicotinoid effects on non-Apis pollinators are expressed most strongly in a rather complex, fitness-related context. Consequently, to fully mitigate long-term impacts on pollinator population dynamics, present pesticide risk assessments need to be expanded to include whole life-cycle fitness estimates, as demonstrated in the present study using O. bicornis as a model.

Ecological and life-history traits predict bee species responses to environmental disturbances

The ability to predict the responses of ecological communities and individual species to human-induced environmental change remains a key issue for ecologists and conservation managers alike. Responses are often variable among species within groups making general predictions difficult. One option is to include ecological trait information that might help to disentangle patterns of response and also provide greater understanding of how particular traits link whole clades to their environment. Although this ‘‘trait-guild” approach has been used for single disturbances, the importance of particular traits on general responses to multiple disturbances has not been explored. We used a mixed model analysis of 19 data sets from throughout the world to test the effect of ecological and life-history traits on the responses of bee species to different types of anthropogenic environmental change. These changes included habitat loss, fragmentation, agricultural intensification, pesticides and fire. Individual traits significantly affected bee species responses to different disturbances and several traits were broadly predictive among multiple disturbances. The location of nests – above vs. below ground – significantly affected response to habitat loss, agricultural intensification, tillage regime (within agriculture) and fire. Species that nested above ground were on average more negatively affected by isolation from natural habitat and intensive agricultural land use than were species nesting below ground. In contrast below-ground-nesting species were more negatively affected by tilling than were above-ground nesters. The response of different nesting guilds to fire depended on the time since the burn. Social bee species were more strongly affected by isolation from natural habitat and pesticides than were solitary bee species. Surprisingly, body size did not consistently affect species responses, despite its importance in determining many aspects of individuals’ interaction with their environment. Although synergistic interactions among traits remain to be explored, individual traits can be useful in predicting and understanding responses of related species to global change.

Local and landscape effects on bee functional guilds in pigeon pea crops in Kenya

Pollinators face many challenges within agricultural systems due to landscape changes and intensification which can affect resource availability that can impact pollination services. This paper examines pigeon pea pollination and considers how landscape context and agricultural intensification in terms of pesticide use affects the abundance of bees characterized by species guilds on crops. The study was conducted on six paired farms across a gradient of habitat complexity based on the distance of each farm from adjacent semi-natural vegetation in Kibwezi Sub-county, Kenya. The study found that farms which do not use insecticides in farm management, but are in close proximity to natural habitat have greater bee guild abundance, but at further distances, overall abundance is reduced with or without insecticide use. At 1 km landscape radius, the complexity of habitats but not patch size had a positive impact on the abundance of cavity nesting bees and mason bees, which can be attributed to the interspersion of the small-holder farms with semi-natural habitats across the landscapes producing mosaics of heterogeneous habitats. The study revealed the strongest relationships between fruit set and bee abundance to be with the carpenter bee, social bee and solitary bee guilds, which are among the most abundant bees visiting pigeon pea flowers in this system. Our findings provide the foundation for conservation efforts by identifying which bee guilds pollinated pigeon peas. From this study, we suggest managing the floral and nesting resources that would best support the most abundant crop pollinators, and also reducing insecticide application to the crop.

Spiroacetals in insects

Spiroacetals, cryptic ketodiols showing a hydroxyl group at both sides of a carbonyl whithin reachable distances are very widespread in nature. A group of 30 different structures, not including stereoisomers, represent volatile, less polar constituents of insect secretions. Five different systems were identified: 1,6-dioxaspirol[4.4]nonanes, 1,6-dioxaspiro[4.5]decanes, 1,6-dioxaspiro[4.6]undecanes, 1,7-dioxaspiro[5.5] undecanes, and 1,7-dioxaspiro[5.6]dodecanes. Some spiroacetals are insect pheromones: (2S,5R)-2-ethyl-1,6-dioxaspiro[4.4]nonane, chalcogran, 1, is a key component of the male produced aggregation pheromone of the spruce bark beetle, Pityogenes cha2cographus. In contrast, (5S,7S)-7-methyl-1,6-dioxaspiro[4.5]decane, 2, conophthorin, acts as a repellent or spacer in several bark beetles. Racemic 1,7-diosaspiro[5.5]undecane, olean, 5, is the female produced sex pheromone of the olive fly, Bactrocera (Dacus) oleae. The most widespread spiroacetal is 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, 8. Tt often forms a mixture of (E,E)- and (E,Z)-isomers, the (E,E)-isomer showing (2S,6R,8S)-configuration. In the solitary bee, Andrena wilkella, it serves as an aggregation pheromone. Present knowledge on structures and distribution of volatile spiroacetals is comprehensively compiled. Stereochemical aspects and mass spectrometric fragmentation patterns are discussed in detail to facilitate identifications of hitherto unknown compounds. Synthetic approaches to spiroacetals are classified and reviewed. Last but not least, facts and speculations on the biosynthesis of volatile spiroacetals are presented.

Interactions between carpenter bees and orchid bees (Hymenoptera: Apidae) in flowers of Bertholletia excelsa Bonpl. (Lecythidaceae)

Competition between two species of bees for the same type of floral resource may generate antagonistic behavior between them, especially in cultivated areas where food resources are limited, seasonally and locally. In this study, was tested the hypothesis of antagonism between two solitary bee species of the family Apidae, Eulaema mocsaryi (Euglossini) and Xylocopa frontalis (Xylocopini), visiting the Brazil nut flowers (Bertholletia excelsa: Lecythidaceae) in a central Amazonia agricultural area. The visitation time was analyzed to detect the possible temporal overlap in the foraging of these bees. Furthermore, was analyzed their interspecific interactions for manipulating flower species visited by an opponent species, as well as attempts to attack this opponent. The individuals of Xylocopa frontalis visited the Brazil nut flowers before Eulaema mocsaryi, although the peak visitation of both did not presented significant differences. Neither of the species manipulated flowers recently visited by opponent species, and there were practically no antagonistic interactions between them. Thus, X. frontalis and E. mocsaryi shared the same food source in the flowers of B. excelsa due to differences in their time of visits and non-aggressive way of interacting with the opponent. This result has important implications for pollinating the Brazil nut, and a possible management of X. frontalis and E. mocsaryi, since these two were the most abundant pollinators in the studied locality.

Small-scale area effect on species richness and nesting occupancy of cavity-nesting bees and wasps

Small-scale area effect on species richness and nesting occupancy of cavity-nesting bees and wasps. The research was conducted in an urban forest remnant in southeast Brazil. We tested the predictions of the following hypotheses: (1) larger areas present higher species richness of bees and wasps, (2) solitary bees and wasps occupy more nests in larger areas, (3) rare species occupy more nests in smaller areas. We sampled Aculeate bees and wasps using trap nests from February to November 2004. We placed trap nests in sampling units (SU) with different size (25, 100 and 400 m²) located in 6 ha of secondary mesophytic forest. One hundred and thirty-seven trap nests were occupied by seven species of bees and four species of wasps. We found an increase in wasp, but not bee species richness following increase in SU size. Hymenoptera richness (i.e. bees plus wasps) was also greater in larger SU. Both the number and density of occupied nests increased with SU size. The wasp Trypoxylon lactitarse responded significantly to area size, larger SU having more occupied nests. The same pattern was exhibited by the wasp Auplopus militaris, the Megachile bee species, and the bee Anthodioctes megachiloides. Only Trypoxylon sp. was not affected by SU size. Our results show that cavity-nesting bee and wasps respond differently to the area effects. Such findings must be complemented by information on the frequency and dynamics of area colonization and nest occupancy by species of solitary Hymenoptera.

Entering behavior of Gasteruption brachychaetum Schrottky (Hymenoptera, Gasteruptiidae) into a nest of Hylaeus Fabricius (Hymenoptera, Colletidae)

Nests of Hylaeus aff. guaraniticus (Schrottky, 1906) were parasited by females of Gasteruption brachychaetum Schrottky, 1906 in trap nests in São Paulo (Brazil). This is thefirst host record of a Gasteruptiidae in the Neotropical Region. The behavior of a G.brachychaetum female entering a host's nest is described as follows: an inquiline female hovered near the host's nest, landed and detected that a female of H. aff. guaraniticus was inside the nest, waited for the host female to fly out, entered backwards into the nest, remained there for almost six minutes, and then went out the nest. The development time of immature stages of G.brachychaetum varied between 16 and 299 days.

Abundance and diversity of wild bees along gradients of heavy metal pollution

1. Wild bees are one of the most important groups of pollinators in the temperate zone. Therefore, population declines have potentially negative impacts for both crop and wildflower pollination. Although heavy metal pollution is recognized to be a problem affecting large parts of the European Union, we currently lack insights into the effects of heavy metals on wild bees. 2. We investigated whether heavy metal pollution is a potential threat to wild bee communities by comparing (i) species number, (ii) diversity and (iii) abundance as well as (iv) natural mortality of emerging bees along two independent gradients of heavy metal pollution, one at Olkusz (OLK), Poland and the other at Avonmouth (AVO), UK. We used standardized nesting traps to measure species richness and abundance of wild bees, and we recorded the heavy metal concentration in pollen collected by the red mason bee Osmia rufa as a measure of pollution. 3. The concentration of cadmium, lead and zinc in pollen collected by bees ranged from a background level in unpolluted sites [OLK: 1·3, 43·4, 99·8 (mg kg−1); AVO: 0·8, 42·0, 56·0 (mg kg−1), respectively] to a high level on sites in the vicinity of the OLK and AVO smelters [OLK: 6·7, 277·0, 440·1 (mg kg−1); AVO: 9·3, 356·2, 592·4 (mg kg−1), respectively]. 4. We found that with increasing heavy metal concentration, there was a steady decrease in the number, diversity and abundance of solitary, wild bees. In the most polluted sites, traps were empty or contained single occupants, whereas in unpolluted sites, the nesting traps collected from 4 to 5 species represented by up to ten individuals. Moreover, the proportion of dead individuals of the solitary bee Megachile ligniseca increased along the heavy metal pollution gradient at OLK from 0·2 in uncontaminated sites to 0·5 in sites with a high concentration of pollution. 5. Synthesis and applications. Our findings highlight the negative relationship between heavy metal pollution and populations of wild bees and suggest that increasing wild bee richness in highly contaminated areas will require special conservation strategies. These may include creating suitable nesting sites and sowing a mixture of flowering plants as well as installing artificial nests with wild bee cocoons in polluted areas. Applying protection plans to wild pollinating bee communities in heavy metal-contaminated areas will contribute to integrated land rehabilitation to minimize the impact of pollution on the environment.

Pollination deficits in UK apple orchards

Apple production in the UK is worth over £100 million per annum and this production is heavily dependent on insect pollination. Despite its importance, it is not clear which insect pollinators carry out the majority of this pollination. Furthermore, it is unknown whether current UK apple production, in terms of both yield and quality, suffers pollination deficits and whether production value could be increased through effective management of pollination services. The present study set out to address some of these unknowns and showed that solitary bee activity is high in orchards and that they could be making a valuable contribution to pollination. Furthermore, fruit set and apple seed number were found to be suffering potential pollination deficits although these were not reflected in apple quality. Deficits could be addressed through orchard management practices to improve the abundance and diversity of wild pollinators. Such practices include provision of additional floral resources and nesting habitats as well as preservation of semi-natural areas. The cost effectiveness of such strategies would need to be understood taking into account the potential gains to the apple industry.

Entering behavior of Gasteruption brachychaetum Schrottky (Hymenoptera, Gasteruptiidae) into a nest of Hylaeus Fabricius (Hymenoptera, Colletidae)

Entering behavior of Gasteruption brachychaetum Schrottky (Hymenoptera, Gasteruptiidae) into a nest of Hylaeus Fabricius (Hymenoptera, Colletidae). Nests of Hylaeus aff. guaraniticus (Schrottky, 1906) were parasited by females of Gasteruption brachychaetum Schrottky, 1906 in trap nests in Sao Paulo(Brazil). This is the first host record of a Gasteruptiidae in the Neotropical Region. The behavior of a G. brachychaetum female entering a host's nest is described as follows: an inquiline female hovered near the host's nest, landed and detected that a female of H. aff. guaraniticus was inside the nest, waited for the host female to fly out, entered backwards into the nest, remained there for almost six minutes, and then went out the nest. The development time of immature stages of G. brachychaetum varied between 16 and 299 days.

Perfil da expressão gênica de larvas de Tetrapedia diversipes (Hymenoptera: Apidae) em diapausa

A diapausa é um fenômeno amplamente presente nos artrópodes e é considerada como primordial para o sucesso evolutivo da Classe Insecta, pois possibilita a sobrevivência em condições adversas, como estações frias e secas. Sabe-se que durante a diapausa ocorre o silenciamento de muitos genes e que outros são unicamente expressos nesta fase. Embora existam evidências de que o processo da diapausa tenha se mantido conservado durante a evolução das espécies, ainda há lacunas no conhecimento sobre o nível de conservação dos padrões metabólicos. Um bom modelo para se estudar a diapausa é Tetrapedia diversipes, uma espécie bivoltina de abelha solitária. Os indivíduos que nascem na primeira geração seguem o desenvolvimento desde ovo até adulto em tempo bem menor do que aqueles que nascem na segunda geração; estes retardam o desenvolvimento na fase larval. Além disso, essa espécie é de fácil obtenção no seu ambiente natural, pois apresenta alta taxa de nidificação em ninhos-armadilha. O objetivo deste trabalho foi comparar o perfil de expressão de genes entre as larvas da 1ª geração (que não entram em diapausa), larvas da 2ª geração (que entrariam em diapausa) e das larvas em diapausa. Foram identificados 196 genes diferencialmente expressos, destes 87 foram anotados. Muitos destes genes já foram descritos na literatura como relacionados à diapausa em outras espécies, no entanto, o padrão de expressão não é conservado. Os genes aqui identificados foram divididos em cinco grupos: relacionados à desintoxicação celular, cutícula e citoesqueleto, metabolismo de lipídeos e esteróis, ciclo celular e outros genes relacionados à diapausa

Advancing of risk assessment of pesticides on insect pollinators: beyond honey bees (Apis mellifera L.)

The western honey bee, Apis mellifera L., is currently the model specie for pesticide risk assessment on pollinators with the assumption that the worst-case scenarios for this species are sufficiently conservative to protect other insect pollinators. However, recent studies have showed that wild species may be more sensitive to plant protection products, due to differences in biology and life cycles. Therefore, there is the need to extend the risk assessment within a more ecological approach, in order to ensure that there are no irreversible effects on non-target organisms and in the environment. My dissertation aims to expand the risk assessment to other insect pollinators (including wild and managed pollinators), in order to cover some of the gaps of the current schemes. In this thesis, it is presented three experiments that cover the early stages of a solitary bee (chapter 1), the development of molecular tools for early detection of sub-lethal effects (chapter 2) and the development of protocols to access lethal and sub-lethal effects on other pollinator taxa (Diptera; chapter 3).