Assemblage of flower visitors to Dillenia suffruticosa and possible negative effects of disturbances in Sarawak,Malaysia

Dillenia suffruticosa (Dilleniaceae), a common pioneer shrub in Southeast Asia, is broadly distributed along roadsides. This species flowers throughout the year and is thought to be a keystone species for maintaining populations of flower visitors. To examine the flower visitors of this species, we conducted field surveys and described the behaviors of each flower visitor species within four different research sites: Primary Forests 1 and 2, Secondary Forest, and Mixed Vegetation. We caught 1087 individuals belonging to 51 species from 11 insect families and one species of arachnid. Most flower visitors belonged to Hymenoptera (98.6% of individuals); Trigona spp. and Xylocopa spp. (Apidae) accounted for 64.0% and 20.0%, respectively, of all caught individuals. According to observations of behavior by each species, effective pollinators may include Xylocopa spp. and Amegilla spp. (Apidae). We compared the research results among four research sites and found that the effective pollinators were not different among sites. However, the number of species and the abundances of flower visitors decreased in disturbed areas, especially in Secondary Forest. This research suggests the effects of human disturbances on the diversity and abundance of flower visitors.     

Bee Venom Induces the Interaction between Phosphorylated Histone Variant,H2AX,and the Intracellular Site of beta-Actin in Liver and Breast Cancer Cells

Bee venom is a natural mixture and candidate anti-cancer agent with selective cytotoxic effect on some cancer cells. However, the cellular mechanisms of how bee venom selectively targets cancer cells remain elusive. The aim of this study was to reveal the genotoxic effect of bee venom in concordance with the location of β-actin protein throughout the nucleus or/and cytoplasm. For this aim, the level of H2AX phosphorylation (γH2AX) and intracellular location of β-actin were assessed by immunofluorescence in liver (HEPG2) and metastatic breast (MDA-MB-231) cancer cell lines compared to normal fibroblasts (NIH3T3) after bee venom treatment. Colocalisation profiles of γH2AX and β-actin in each cell line were also analysed. The results showed that the levels of γH2AX staining decreased in normal cells but increased in cancer cells. The majority of β-actin was localised within the cytoplasm of normal cells after bee venom treatment, but it was mostly accumulated within the nucleus in cancer cells. Colocalisation of β-actin and γH2AX both in nucleus and cytoplasm was induced in each cancer cell by different patterns. The results showed that normal and cancerous cells had different responses against bee venom, and suggested that bee venom induced a cellular response by the interaction between γH2AX and β-actin.     

Relationships between wild bee abundance and fruit set of Camellia oleifera Abel

Camellia oleifera Abel. is an economically important plant for edible oils. To investigate the importance of wild bee abundance at different canopy and spatial scale for fruit set of Camellia oleifera, we evaluated the relationship of bee abundance with fruit set using yellow pan trap, with additional focus on distance and wild bee abundance counts at a farm in China for 2 years. We found that yellow traps collected 95% more individual bees than the second-best (pink) trap colour. Looking across canopy positions, the number of wild bees (including Colletes gigas, Andrena camellia, Andrena striata, Andrena hunanensis and Andrena chekiangensis) varied significantly in each year. The fruit set also varied significantly based on canopy position. In 2018, there was with an average fruit set of 34.13% in the lower canopy, 54.30% in the middle canopy and 47.41% in the upper canopy. In 2019, fruit set was 29.67% in the lower canopy, 54.15% in the middle canopy and 47.36% in the upper canopy. Comparing inter-annual changes, only the fruit set and number of bees in the low canopy showed significant differences between 2018 and 2019. Fruit set and wild bee abundance were positively correlated in all canopy layers in each year, and there was an interactive effect between canopy and bee abundance on fruit set. Across 205 trees, growth indicators, crown size and tree height, increased significantly from 2018 to 2019, but the fruit set did not increase with the significant increase in the number of flowers. From the spatial perspective, wild bee abundance and fruit set were positively correlated, but fruit set was negatively correlated with distance from a large bee nesting aggregation nearby. Among the variables investigated, bee abundance seems to have the strongest influence on fruit set in C. oleifera.     

Eine schnelle biologische Methode zum Nachweis der Phytotoxizität von Wirkstoffen in Pestiziden mit Hilfe eines Blattaufstiegtestes bei Sinapis alba L. Kotyledonen: (Kurze Mitteilung)

The present work was carried out to study the relationship between brood rearing activity, bee density and stored pollen grains. Fifteen colonies, 1st. Carniolan hybrid nearly in equal strength were put under investigation from June 1994 to May 1995.

The results revealed that the major peak of brood activity and higher rate of stored pollen were in May, consequently the maximum number of house bees was recorded during June and July. However no correlation existed, the lowest production of brood, bees and gathered pollen occurred during February. It was found that high significant differences were in quantity of brood and house bees, while low significant differences were in quantity of stored pollen. Correlations between brood activity, house bees density and stored pollen were observed in winter.     

Foraging behaviour of the stingless bee Melipona orbignyi (Hymenoptera: Apidae: Meliponini) in a dry forest assessed by multivariate analysis from palynological data

Pollen analysis was applied to study the botanical composition of honey and pollen stored by Melipona orbignyi in its southernmost distributional range. Many studies have revealed that robust buzzing bees of this genus are associated with diverse plant families, some of which are different to those exploited by the remaining genera of Meliponini. Cluster analysis was performed to assess similarity in botanical composition between pot-pollen and pot-honey provisions from different colonies. The results indicated that each colony was capable to access to different plant species for obtaining nectar and pollen, a fact observed when discarding the contaminated honey samples. As honey samples were not clustered together with other ones but with pollen samples indicating a similar botanical composition, it could be assumed that a same plant species provided nectar and pollen to bees. Resource partitioning was not clearly observed among a subset of late spring colonies, as two families of high richness of species and abundant in this dry forest (the mimosoid clade in Fabaceae and Capparaceae) were foraged. A higher number of synchronously sampled colonies would be necessary to detect this ecological aspect. The botanical composition of samples of M. orbignyi was governed by both random factors such as local and temporary flower availability plus preferences for particular plant species such as those from Solanaceae and Ximeniaceae. The Capparaceae and Ximeniaceae are here reported for the first time as intensively foraged pollen resources by the genus Melipona.     

Regulation of nectar collection in relation to honey storage levels by honey bees, Apis mellifera

Honey bees collect distinct nutrient sources in the form ofnectar (energy) and pollen (nitrogen). We investigated the effectof varying energy stores on nectar and pollen foraging. We foundno significant changes in nectar foraging in response to changesin honey storage levels within colonies. Individual foragersdid not vary activity rates or nectar load sizes in responseto changes in honey stores, and colonies did not increase nectarintake rates when honey stores within the hive were decreased.This result contrasts with pollen foraging behavior, which isextremely sensitive to colony state. Our data show that individualforaging decisions during nectar collection and colony regulationof nectar intake are distincdy different from pollen foraging.The behavior of honey bees illustrates that foraging strategy(and therefore foraging models) can incorporate multiple currencies,including both energy and protein intake.[Behav Ecol 7: 286–291(1996)]     

Pathogenicity of the entomogenous fungi Metarhizium anisopliae and Beauveria bassiana against crucifer pests and the honey bee

The susceptibility of the cabbage stem flea beetle (Psylliodes chrysocephala; Coleoptera: Chrysomelidae) to different isolates of the entomogenous, hyphomycete fungi Beauveria bassiana and Metarhizium anisopliae, all from heterologous hosts, was investigated. The most pathogenic isolates were of M. anisopliae (V208, V233, V234, V242, V245, and V248). Studies were conducted to determine the virulence of V208 and V245, and their specificity for three other crucifer pests, Phaedon cochleariae, Myzus persicae and Lipaphis erysimi and a beneficial insect, Apis mellifera. Flea beetle mortality rates increased with dose; the estimated LC₅₀ ^S of V208 and V245 at 14 days post‐inoculation were c. 10⁶ conidia ml^‐1. The respective estimated LT₅₀ values of V208 and V245 for P. chrysocephala at 1 × 10⁷ conidia ml^‐1 were 10.0 and 9.3 days, and at 1 × 10¹⁰ conidia ml LT₅₀s were 3.8 and 4.2 days. Both V208 and V245 were pathogenic for P. cochleariaeM. persicae and L. erysimi. Myzus persicae and L. erysimi died within 4 days of inoculation. Bees were less susceptible to infection at low doses, but at 1 × 10¹⁰ conidia ml^‐1almost all bees had died by day 5 when the estimated LT₅₀s for V208 and V245 were 4.4 and 8.5 days respectively.