Interaction networks between solitary hymenopterans and their natural enemies in different restoration areas

The diversity of species and their interactions have been positively related with environmental complexity. Therefore, highly anthropized environments have their integrity under serious threat. These effects may last for years compromising the dynamics of natural communities, such as antagonistic and mutualistic interactions, including host-natural enemy interactions. To investigate these effects, trap nest methodology was used to assess the diversity of solitary bees, wasps and their natural enemies in three fragmented environments with different degree of anthropic perturbation, composed of a Eucalyptus plantation (considered here as higher perturbation), a Cerrado area (medium perturbation) and a Riparian forest (lesser perturbation). Then, host-natural enemies associations were analysed to verify the size, specialization degree and modularity of interaction network. The gradient from highest to lowest degree of anthropic perturbation was evidenced in the species diversity index, the size of the interaction network and the specialization indexes of the host-natural enemy network. The environment with Eucalyptus plantation showed higher values of diversity of natural enemies, greater number of species in the interaction network, lesser degree of specialization in the interaction and lesser modularity, than Cerrado and Riparian forest environments, respectively. The low degree of nestedness and lack of significance of this index to all sampled areas are indicative of a specialized pattern of networks. The results corroborate the notion that human impact may affect interaction networks, this being an important tool for checking the degree of anthropic alteration.

Nests of Eufriesea aff. auriceps (Hymenoptera, Apidae, Euglossini) in remnants of Atlantic Forest and reforested areas

In recent decades, the use of the trap-nest technique has helped to increase knowledge on the nest architecture of many orchid bee species. This study describes the nest architecture of Eufriesea aff. auriceps constructed in trap-nests made of dried bamboo internodes (canes). The nests were placed in remnants of Atlantic forest and in reforested areas next to forest remnants and monitored monthly from August 2015 to August 2016 and from August 2018 to August 2019 in southern Brazil. The bamboo internodes occupied by bees varied in internal diameter from 1.0cm to 2.0 cm (`X = 1.7; SD = 0.3; N = 12) and in length from 11.0 cm to 28.0 cm (`X = 19.5; SD = 4.8; N = 12). The total size of the nests inside the bamboo internodes ranged from 9.0 cm to 19.9 cm (`X = 14.3; SD= 3.9; N = 12). The number of brood cells constructed per nest varied from 1 to 10 (`X = 4.0; SD = 2.3; N = 15). The cells were built with small pieces of bark cemented with resin, linearly arranged along the bamboo tube. Internally, the cell wall was lined with resin. The cells measured 1.5-3.0 cm (`X = 2.3 ± 0.5; N = 48) in length and 1.4-1.7 (`X = 1.5 ± 0.1; N = 17) cm in width. The internal contour of the cells was elliptical. Females of Eufriesea aff. auriceps occupied trap-nests in both the forest remnants and in areas undergoing restoration.

A new host record for the cleptoparasite Irenangelus lucidus (Evans, 1969) (Hymenoptera: Pompilidae)

We provide a new host record for the cleptoparasitic wasp Irenangelus lucidus (Evans, 1969) (Pompilidae: Ceropalinae). A single female emerged from a brood cell of the host species Auplopus militaris (Lynch-Arribalzaga, 1873) (Pompilidae: Pepsinae) reared from a bamboo cane trap nest set at the edge of a gallery forest fragment located in Minas Gerais State, Central Brazil. This is the third host record of an Irenangelus species for the Neotropical region.

A bilateral gynandromorph of Discoelius dufourii (Hymenoptera, Vespidae, Zethinae): morphology and mating behaviour

A gynandromorph is an organism combining both female- and male-type tissues. While the vast majority of studies have described the morphology of gynandromorphs, their sexual behaviours remain under-explored. We studied a predominantly bilateral gynandromorph specimen of the predatory wasp Discoelius dufourii (Hymenoptera: Vespidae: Zethinae) reared from a trap-nest. In addition to describing the morphology, we explored the gynandromorph’s response to a conspecific female, comparing it with the behavioural interactions between normal males and females of D. dufourii and the phylogenetically related D. zonalis. For most specific behavioural elements, males of both Discoelius species exhibited a greater frequency and a higher probability of occurrences of the behaviour than did females. However, aggression and plopping behaviours were prevalent in females. The gynandromorphic specimen demonstrated behavioural activities similar to those of a male, including a relatively frequent mate body antennation and an attempt to mount a female. However, it approached the female less frequently in comparison to conspecific normal males, and it did not demonstrate substrate antennation and jumping, typical of Discoelius male mating behaviour. Based on the parameters of the nest cell, the probability of the development of the gynandromorphic specimen from an unfertilized (male) egg was higher than the probability of development from a fertilized (female) egg.

Nests of some representatives of hymenoptera (Hymenoptera, Aculeata) in stationary artificial nesting structures on the territory of the botanical garden NUBIP of Ukraine

Green areas of the city (remnants of the natural landscape, parks, squares, etc.) are a refuge for most diverse organisms, include insects too. Such places provide them with fodder and nesting resources under certain conditions. However, as a result of the sanitary measures of a care, the simplification of the vegetation, etc., these places become unattractive to biota, which leads to the reduction of the most common urbotolerant species of insects. In order to preserve and maintain populations of some insect species, artificial nesting structures are installed in the most attractive and safe areas. We studied the trap nest (a set of reed tubes) for insects, which was located on the territory of the botanical garden NUBIP of Ukraine. As a result of the study of 50 separate nests, the species composition of individual groups of the wild bees and wasps inhabiting such nests was described. Measurements of individual nests (diameter and length of the reed tube) were made and it was found that the population of the insects, in particular Osmia bicornis (Linnaeus, 1758) (Apoidea, Megachilidae) and the wasps of the genus Trypoxylon Latreille, 1896 (Crabronidae) is almost 95 % with dominance of O. bicornis (78 %). It was determined that Osmia are not preferred to the nest with tubes of larger diameter or length, but the diameter and length of the reed tubes are positively correlated with the number of the bees larvae in the nest (the correlation coefficients are 0.44 and 0.48, p = 0.05, respectively). The wasps (Trypoxylon sp.) was preferred to the tubes with a diameter of mainly 0.5-0.7 cm (r = 0.56, p = 0.05). In addition, the composition of kleptoparasites, which lead to the death of the bee larvae, was studied. Thus, 20 % of Osmia nests were infected with flies Cacoxenus indagator Loew, 1858 (Diptera, Drosophilidae), and 10 % of the nests contained pollen mite Chaetodactylus osmiae (Dufour, 1839) (Arachnida, Sarcoptiformes).

Unveiling the trap-nesting bees and wasps’ fauna (Hymenoptera: Apocrita) and associated organisms of the Jardim Botânico do Rio de Janeiro, Brazil

Urban areas, as cities, are frequently overlooked as refuges for the native fauna. However, these places may support several species and house relevant biodiversity contributing to important ecosystemic functions. Wasps and bees (Hymenoptera: Apocrita) are important faunistic elements acting as predators/parasitoids and pollinators, respectively. Therefore, they must be surveyed and inventoried for conservation purposes, especially in cities located in the Atlantic Forest domain, a ravaged Brazilian biome. Accordingly, this study presents a species list of trap-nesting bees and wasps that occurs at the Jardim Botânico do Rio de Janeiro. The survey was conducted using the trap-nest method. Three types of trap-nests were offered totalizing 1,038 traps: rubber hose, bamboo cane and plastic straw. The plastic straw traps were the most effective followed by the bamboo cane ones at attracting nesting wasps and bees. Between April/2017 and February/2019, 12 foundress species built nests: Tetrapedia curvitarsis (Apidae) (33 nests), Hylaeus sp. (Colletidae) (6), Auplopus cf. rufipes (Pompilidae) (5), Trypoxylon sp. (Crabronidae) (4), Pachodynerus nasidens (Vespidae) (3), Auplopus cf. brasiliensis (Pompilidae), Megachile benigna and Megachile sp. (Megachilidae), Euglossa pleosticta, Euglossa sp., and Eufriesea sp. (Apidae) and Penepodium sp. (Sphecidae) all with one nest. Also, four natural enemies were recorded: Chaenotetrastichus neotropicalis (Eulophidae), Gasteruption brachychaetum (Gasterupteiidae), Caenochrysis crotonis (Chrysididae) and Amobia sp. (Diptera: Sarcophagidae). Most bee nests were restrained to the matrix forest and nearby areas, whereas wasps built their nests predominantly in open areas. Regarding seasonality, bees tended to nest in the summer and early autumn influenced by mean temperature, in contrast of wasps that nested in late autumn, winter and spring, influenced by pluviosity. Besides many rare species, which suggests environmental disturbance, the Jardim Botânico do Rio de Janeiro showed a fairly diverse fauna and shows how forest fragment in cities may harbour important representatives of the native fauna.

Cavity Length Affects the Occupation of Trap-Nests by Centris analis and Tetrapedia diversipes (Hymenoptera: Apidae)

The ideal cavity dimensions for neotropical cavity-nesting bees with the potential to be managed as pollinators have not been getting proper attention. We investigated whether the occupancy of trap-nests by Centris analis Fabricius and Tetrapedia diversipes Klug, and other nesting aspects, are affected by different trap-nest length. The used trap-nests were cardboard tubes 5, 10, 15 and 20 cm in length, and Ø 8 mm. Occupation rates of 10-cm trap-nests by C. analis was higher than that of the 5-cm ones (χ2=11.17, gl=1, p<0.001). On the other hand, there was not difference between the occupation rates of 10 and 15-cm long trap-nests (χ2=0.51, gl=1, p=0.48), and between the ones measuring 15 and 20 cm long (χ2=1.36, gl=1, p=0.24). T. diversipes occupied a smaller number of 5-cm trap-nests than the 10-cm ones (χ2=1.52, gl=1, p=0.22), as well as that the 15-cm ones were more occupied than the 10-cm trap-nests (χ2=4.23, gl=1, p=0.04); moreover, there was not difference between the occupation of 15 and 20-cm trap-nests (χ2=0.28, gl=1, p=0.59). Both species showed higher rates of dead immatures in nests set in the shortest trap-nests, whereas these mortality rates were lower in the longest ones. By taking into consideration that there was not significant difference in many of the assessed parameters in comparison to values recorded for 15 and 20-cm long trap-nests, it seems likely to recommend the adoption of 10-cm long trap-nests for C. analis reproduction in agricultural sites that depend on the pollination service provided by this bees species.

Occupation and Emergence of Solitary Bees in Different Types of Trap Nests

The study investigated the occupation and emergence of bees that nest in trap-nests and assessed aspects of the structure of such nests, sex ratio, parasitism and mortality of bees in four areas of Baturité Massif, State of Ceará. Samples were taken using three types of trap-nests: dried bamboo internodes, cardboard tubes and rational boxes. In the four studied sites, a total of 185 artificial nests were offered monthly and 34 of them were occupied by bees. Six species of bees, distributed in five genera (Centris, Mesocheira, Euglossa, Megachile and Coelioxys) occupied the 34 trap-nests, but of this total nests, 24 presented emergence of individuals. In the rest of the nests there was mortality of the occupants. Considering the total of nests with emergence, it was obtained 139 individuals: 131 bees (28 kleptoparasite bees) and 8 coleopterans. In 34 bee nests obtained, there were constructed 162 brood cells, the number of cells per trap-nest varied from 1 to 13 brood cells and the length of these nests varied from 2.4 to 14cm. Thirteen nests were parasitized by hymenopterans (Apidae and Megachilidae) and coleopterans (Meloidae), resulting in a parasitism rate of 38.2% of the total of nests founded. In addition, mortality occurred from unknown causes in 29.4% (n=10) of individuals before reaching adult stage. This work identified the bee species that use pre-existing cavities in the Baturite Massif, determined their nesting requirements and constrains for their reproduction. This information may contribute to conservation efforts of these bee species as well as their potential use for pollination services.

Natural enemies of the oil-collecting bee Centris analis (Fabricius, 1804) with notes on the behavior of the cleptoparasite Coelioxys nigrofimbriata Cockerell, 1919 (Hymenoptera, Apidae)

This work presents a review of natural enemy species associated with Centrisanalis and summarizes the available information on life history, behavior, diversity, and specialization of these taxa. Records include over 20 species in ten genera from seven distinct families of Hymenoptera, Diptera and Coleoptera. These species are cleptoparasites or parasitoids of immature stages or adults. Some species seem to be occasional parasitoids, while others seem to be more frequent and responsible for significant mortality rates of immatures in nests. Three families of Hymenoptera represent the majority of natural enemy taxa found in C.analis nests: Apidae, Chrysididae, and Leucospidae. The most frequent parasitoid reared from nests was the wasp Leucospiscayennensis Westwood, followed by cleptoparasitic bee species of the genus Coelioxys Latreille. Vouchers of trap nest studies are identified for the first time and refer to Coelioxysnigrofimbriata Cockerell, which seems to have a strong association with nests of C.analis. Further direct observation notes about biology and behavior of C.nigrofimbriata are also provided.