Wood ant assemblages of Formica rufa group on lake islands and in mainland woodland in Central Finland

Associations of island size and isolation on the occurrence and species richness of five wood ant species of the Formica rufa group (F. rufa, F. aquilonia, F. lugubris, F. polyctena and F. pratensis) was tested in the Lake Konnevesi archipelago in Central Finland. In addition, the species composition was compared to that of mainland forests of the same region. Island isolation had no associations with the wood ant occurrence in this archipelago, but for most species, increasing island size was positively associated with the occurrence probability. According to the findings among the five species, Formica lugubris is the best adapted for insular living. There was a positive species–area relationship as the species richness of wood ants increased with an increasing island size. The island community of wood ants was dominated by colonies of the monogynous (single queen) species whereas the mainland community was dominated by those of polygynous (multiple queen) species

Social wasp (Hymenoptera: Vespidae) beer trapping in Finland 2008-2012: a German surprise

Beer trapping has been carried out annually in the summer in south western Finland (Turku) from 2008 to 2012 inclusive. In 2012, an additional trapping programme was conducted in southern (Helsinki), central (Kuopio) and northern (Kevo) Finland, which also included another trapping location in the south western (Turku) region. The traps were always presented for seven days in each location. While the median wasp Dolichovespula media (Retzius, 1783) was present in all locations, the common wasp Vespula vulgaris Linnaeus, 1758 was found in five out of six locations (20 traps per site). The Kevo individual represents the northernmost record for the median wasp species. The German wasp Vespula germanica (Fabricius, 1793) was surprisingly common in south western and southern Finland. Vespula germanica has a short history of occurrence in Finland and seems to have shifted its range northwards, possibly due to climate change. Some common species of the genus Dolichovespula Rohwer, 1916 were likely underrepresented, because they are not very attracted by beer

Two distinct morphs in the wood ant Formica polyctena in Finland: a result of hybridization?

Wide overlaps in morphological characters among species in mound building wood ants of the Formica rufa-group have been a long-standing problem. Previous studies suggest that Formica polyctena samples from Finland may represent two different types based on queen morphology. However, worker caste has not been studied completely. I found that hairiness of workers from different colonies was bimodally distributed. Morphs (based on bimodality) differed in the abundance of erect hairs on eight out of 11 studied body parts. The hairier morph may be result of incomplete reproductive isolation between closely related species

Acceptance of alien queens by the ruby ant Myrmica rubra (Hymenoptera: Formicidae): Gene flow by queen flow

Social insect colonies, especially of ants, often include several egg-laying queens that are not always closely related to each other. At least in some cases, the ants seem to accept non-related queens into their colonies. Here I test whether the colony queen status (with or without a queen), genetic and geographic differences between source and recipient nests and the average relatedness of the workers in the recipient colony affect the acceptance of alien queens. I used field collected ruby ant Myrmica rubra colonies as a model system. Only the queen status significantly affected the acceptance process. Colonies without queens accepted alien queens more frequently than colonies with a queen. The nests without queens and nest fragments may act as vectors for gene flow by the movement of queens between nests, i.e., queen flow

Aspartame-based Sweetener as a Strong Ant Poison: Falsifying an Urban Legend?

Information about the usability of artificial sweeteners, mainly aspartame, for controlling pest ants has spread widely in the internet. With a laboratory experiment we tested the effect of an aspartame based sweetener on the mortality of the black garden ant Lasius niger, a common pest ant in kitchens in Europe. The aspartame-based sweetener was added to the laboratory jelly food of ants in the experimental group (16 colonies). The control group (14 colonies) received otherwise similar jelly but without the aspartame-based sweetener. During the 35 day period of experiment we did not find any signs of aspartame induced mortality in tested ants. In addition, 135 colony founding L. niger queens were submerged in a sweetener solution (artificial sweetener + distilled water) and 135 queens were submerged in distilled water (control). The overall mortality was very low (<1.5%) and no between-group differences in mortality were found within 24 and 96 hours. Our results strongly oppose the rumors that aspartame sweeteners are effective as an ant poison, at least with a typical dose of household aspartame products

Terpenes and fungal biomass in the nest mounds of Formica aquilonia wood ants

AbstractNest mounds of wood ants of the Formica rufa group are built using conifer needles, small branches, other plant materials and soil. Conifer needles contain several mono and sesquiterpenes. Thus, wood ant nests may act as terpene hotspots in conifer forest soils. Some of the terpenes show antifungal activity and may thus cause small-scale heterogeneity in fungal biomass. We compared terpene concentrations and fungal biomass (ergosterol concentration) of nest material of the wood ant Formica aquilonia from the top, core and basement of 14 nest mounds in eastern Finland. Overall, α-pinene, camphene, sabinene, β-pinene, myrcene, limonene, camphor and longifolene were detected the most and were commonly present in all the studied layers. We found that terpene concentrations differed between the sampled nest material layers, being generally highest in the core of the nest and lowest at the basement of the nest. There was no association between the terpene concentration and material moisture. Fungal biomass was highest in the top layer, intermediate in core and lowest in basement; however, it was not negatively associated with terpene concentrations. Fungal biomass in nest mounds was positively associated with moisture and alkalinity. Nest mounds of Formica rufa group wood ants are complex structures with different chemical and microbial properties among its layers.</p

First record of an indoor pest sawtoothed grain beetle Oryzaephilus surinamensis (Coleoptera: Silvanidae) from wild outdoor wood ant nest

Alive individual adult sawtoothed grain beetle Oryzaephilus surinamensis (Linnaeus, 1758) was discovered inside a nest mound of the red wood ant Formica rufa Linnaeus, 1758 during a survey of myrmecophilous invertebrates. The sawtoothed grain beetle is a widespread indoor pest that has not previously been found in an ant nest. It is one of the most common pests in stored grain and cereal products, but the natural life-style of the species is not known. As the site of discovery was exceptional, we verified the species identification using the DNA barcode. If the sawtoothed grain beetle can live in mounds of red wood ants, the mounds may become widespread source habitats for the future infestations of this serious stored product pest

Status and monitoring of the buff-tailed bumblebee Bombus terrestris Linnaeus (Hymenoptera: Apidae) in Southern Finland

Bombus terrestris can cause pollination disturbance in native plants and compete with native bumblebees and other pollinators. The accompanying non-native parasites may also threaten native bees. We report new observations of the commercially used Bombus terrestris (Linnaeus, 1758) using trapping data and sporadic samples identified with a PCR–RFLP-method for degraded DNA. A total of 863 individuals (355 queens, 442 workers, 66 drones) of Bombus sensu stricto were collected during the years 2008–9, of which, 642 were B. lucorum, ten B. cryptarum, four B. terrestris and none were B. magnus. Three trap types were compared in two modified transects near areas that use the commercial B. terrestris for pollination in Southern Finland: the tree trap that was hung at approximately 3 metres height was the most effective. Regular monitoring is important in the risk assessment of B. terrestris, and for correct species identification, molecular methods are recommended

Comparison of ant-associated beetle communities inhabiting mounds of forest-dwelling ants in forests and forest clearings

Red wood ant (Formica rufa group) nests contain a highly diverse community of invertebrates, which is largely due to their abundant resources and regulated microclimatic conditions. Clear-felling, however, causes nest mounds to lose surface layer moisture, thus disrupting their inner stability. To study the effects of clear-felling on ant-associated beetles (myrmecophile and non-myrmecophile), 41 nests of Formica aquilonia Yarrow, 1955 located on three clear-fells and adjacent mature forest stands were sampled, and the beetle communities between these habitats were compared. We investigated how habitat type, nest surface moisture content, nest volume, and isolation affect the community composition, species richness, and abundance of beetles. Beetle community composition or species richness did not markedly differ between clearings and forests, although total abundance was higher in forests. Also, total species richness and abundance and myrmecophile abundance increased with increasing moisture content. Overall, nests with similar moisture content and volume had similar species compositions. Nest volume was negatively correlated with myrmecophile species richness. Nest isolation was not related to species richness or abundance. The lower abundances in clearings could be problematic in the long term, as small populations are more likely to become extinct. To ensure the survival of ants and their associates, small-scale clearings should be preferred

Effect of host species, host nest density and nest size on the occurrence of the shining guest ant Formicoxenus nitidulus (Hymenoptera: Formicidae)

Understanding habitat requirements of species is important in conservation. As an obligate ant nest associate, the survival of the globally vulnerable shining guest ant, Formicoxenus nitidulus, is strictly tied to that of its hosts (mound building Formica ants). We investigated how host species, nest density, inter-nest distance and nest mound size relate to the occurrence of F. nitidulus. In total, 166 red wood ant nests were surveyed in SW Finland (120 Formica polyctena, 25 F. rufa, 14 F. aquilonia, 5 F. pratensis, and 2 F. lugubris). Overall, F. nitidulus was found in 60% of the nests. For the actual analysis, only F. polyctena and F. rufa nests were included due to the small number of other nests. F. nitidulus was more likely to be found among F. polyctena than F. rufa. Also, while inter-nest distance was not important, a high nest density, commonly found in polydomous (multi-nest) wood ant colonies, was beneficial for F. nitidulus. The guest ant was also more likely to be found in large host nests than small nests. Thus, our results show that the best habitat for the guest ant is a dense population of host nest mounds with a high proportion of large mounds. Conservation efforts should be directed at keeping the quality of the red wood ant habitats high to preserve their current populations and to increase colonization. This will not only benefit the guest ant, but also a plethora of other species, and help in maintaining the biodiversity of forests.</p