Nesting of arboreal ants (Hymenoptera: Formicidae) in artificial substrates in coffee plantations in the Colombian Andes

Ants can provide pest biocontrol for coffee crops; however, this ecosystem service may decline in intensively managed plantations due to the loss of nesting resources. Considering how to increase the number of ants, we studied if they nest in different types of artificial substrates attached to coffee bushes both in shade-grown and sun-grown coffee plantations. Three independent tests were conducted at some coffee plantations in southwestern Colombia with the purpose of answering the following questions: 1) Do ants nest in artificial substrates made from recyclable materials? 2) Do the types of substrate (materials and configuration) and coffee management (shade-grown vs. sun-grown coffee) affect colonization rates, richness, and identity of colonizing ants? 3) Does time affect substrate colonization rates? Each experiment independently compared different substrate materials and designs, in both shade and sun-grown coffee. Results showed preference of one of the substrates offered and higher nesting rates in shade-grown plantations. Eight ant species were found nesting in artificial substrates, most of them being arboreal generalists. A higher number of ant species colonized substrates in shade-grown plantations; however, the effect was not statistically significant. Nesomyrmex asper and Crematogaster spp. were always found nesting in both types of plantation. There was a trend to increase nesting activity with time in shade-grown coffee but not in sun-grown coffee. Evidence supports that offering artificial substrates enhances arboreal ant nesting in coffee plantations.

Bumble bees in landscapes with abundant floral resources have lower pathogen loads

The pollination services provided by bees are essential for supporting natural and agricultural ecosystems. However, bee population declines have been documented across the world. Many of the factors known to undermine bee health (e.g., poor nutrition) can decrease immunocompetence and, thereby, increase bees’ susceptibility to diseases. Given the myriad of stressors that can exacerbate disease in wild bee populations, assessments of the relative impact of landscape habitat conditions on bee pathogen prevalence are needed to effectively conserve pollinator populations. Herein, we assess how landscape-level conditions, including various metrics of floral/nesting resources, insecticides, weather, and honey bee (Apis mellifera) abundance, drive variation in wild bumble bee (Bombus impatiens) pathogen loads. Specifically, we screened 890 bumble bee workers from varied habitats in Pennsylvania, USA for three pathogens (deformed wing virus, black queen cell virus, and Vairimorpha (= Nosema) bombi), Defensin expression, and body size. Bumble bees collected within low-quality landscapes exhibited the highest pathogen loads, with spring floral resources and nesting habitat availability serving as the main drivers. We also found higher loads of pathogens where honey bee apiaries are more abundant, a positive relationship between Vairimorpha loads and rainfall, and differences in pathogens by geographic region. Collectively, our results highlight the need to support high-quality landscapes (i.e., those with abundant floral/nesting resources) to maintain healthy wild bee populations.

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).

Decline of six native mason bee species following the arrival of an exotic congener

A potential driver of pollinator declines that has been hypothesized but seldom documented is the introduction of exotic pollinator species. International trade often involves movement of many insect pollinators, especially bees, beyond their natural range. For agricultural purposes or by inadvertent cargo shipment, bee species successfully establishing in new ranges could compete with native bees for food and nesting resources. In the Mid-Atlantic United States, two Asian species of mason bee (Osmia taurus and O. cornifrons) have become recently established. Using pan-trap records from the Mid-Atlantic US, we examined catch abundance of two exotic and six native Osmia species over the span of fifteen years (2003–2017) to estimate abundance changes. All native species showed substantial annual declines, resulting in cumulative catch losses ranging 76–91% since 2003. Exotic species fared much better, with O. cornifrons stable and O. taurus increasing by 800% since 2003. We characterize the areas of niche overlap that may lead to competition between native and exotic species of Osmia, and we discuss how disease spillover and enemy release in this system may result in the patterns we document.

Aberrant cocoons found on honey bee comb cells are found to be Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae)

Potential biological threats to honey bees must be addressed and validated quickly, before making disruptive and costly decisions. Here we describe numerous Osmia cornifrons (Hymenoptera: Megachilidae) cocoons in honey bee cells from one bee hive in Ohio. The developing Osmia cells presented themselves as a mystery at first, catching the attention of regulatory agencies. Along with identifying this species as a presumably benign resident in honey bee colonies, our observations suggest Osmia may use stored honey bee resources to provision offspring. Conceivably, resident honey bees might even act as surrogates, by provisioning Osmia offspring with pollen. Since the cocoons were attached to one another with honey bee wax, it seems likely that honey bee hosts were present during Osmia development. Osmia females have some plasticity when selecting nesting resources, and, upon discovering honey bee comb can use this resource for raising offspring. Along with resolving a potentially new biotic threat to honey bees, this diagnosis suggests a method for mass production of Osmia pollinators using an array of single cell foundation.

Arboreal twig-nesting ants form dominance hierarchies over nesting resources

Interspecific dominance hierarchies have been widely reported across animal systems. High-ranking species are expected to monopolize more resources than low-ranking species via resource monopolization. In some ant species, dominance hierarchies have been used to explain species coexistence and community structure. However, it remains unclear whether or in what contexts dominance hierarchies occur in tropical ant communities. This study seeks to examine whether arboreal twig-nesting ants competing for nesting resources in a Mexican coffee agricultural ecosystem are arranged in a linear dominance hierarchy. We described the dominance relationships among 10 species of ants and measured the uncertainty and steepness of the inferred dominance hierarchy. We also assessed the orderliness of the hierarchy by considering species interactions at the network level. Based on the randomized Elo-rating method, we found that the twig-nesting ant species Myrmelachista mexicana ranked highest in the ranking, while Pseudomyrmex ejectus was ranked as the lowest in the hierarchy. Our results show that the hierarchy was intermediate in its steepness, suggesting that the probability of higher ranked species winning contests against lower ranked species was fairly high. Motif analysis and significant excess of triads further revealed that the species networks were largely transitive. This study highlights that some tropical arboreal ant communities organize into dominance hierarchies.