Evaluation of seed-dispersal services by ants at a temperate pasture: Results of direct observations in an ant suppression experiment.

Ants disperse seeds of many plant species adapted to myrmecochory. While advantages of this ant-plant mutualism for myrmecochorous plants (myrmecochores) have been previously studied in temperate region mostly in forests, our study system was a pasture. Moreover, we used a unique combination of observing the effect of ant-activity suppression on ant dispersal and comparison of the contribution of ant and unassisted dispersal to the distance from mother plant. We established plots without and with ant-activity suppression (enclosures). We offered diaspores of a myrmecochorous (Knautia arvensis), and a non-myrmecochorous (Plantago lanceolata) species in a choice test and followed ants carrying diaspores during days and nights (focus of previous studies was on diurnal dispersal). We measured frequency and distances of ant dispersal and compared them with unassisted dispersal recorded using sticky trap method. The dispersal frequency was lower in enclosures (3.16 times). Ants strongly preferred diaspores of the myrmecochore to non-myrmecochore with 586 and 42 dispersal events, respectively (out of 6400 diaspores of each species offered). Ant dispersal resulted in more even and on average longer distances (maximum almost tenfold longer, 994 cm) in comparison to unassisted dispersal. Ant dispersal altered the distribution of distances of the myrmecochore from roughly symmetric for unassisted dispersal to positively skewed. Ants dispersed heavier diaspores farther. Ants dropped the majority of diaspores during the dispersal (which reduces clustering of seeds), while several (11%) were carried into anthills. Anthills are disturbed microsites presumably favorable for germination in competitive habitats. Ants provided non-negligible dispersal services to myrmecochorous K. arvensis but also, to a lesser extent, of non-myrmecochorous P. lanceolata.

Low concentrations of acetamiprid, deltamethrin, and sulfoxaflor, three commonly used insecticides, adversely affect ant queen survival and egg laying.

Ants are key ecosystem service providers and can serve as important biological control agents in pest management. However, the effects of insecticides on common farmland ant species are poorly understood. We tested the effects of three commonly used insecticides on ants (Hymenoptera, Formicidae). The tested insecticides were acetamiprid (neonicotinoid; formulated as Mospilan 20 SP), deltamethrin (pyrethroid; formulated as Sanium Ultra), and sulfoxaflor (sulfilimine; formulated as Gondola). We tested two ant (Hymenoptera: Formicidae) species with different colony founding strategies, Lasius niger (Linnaeus, 1758) and Myrmica rubra (Linnaeus, 1758). We sprayed their queens with insecticides at concentrations recommended for use in foliar applications in agriculture, i.e., at 1.25 g L-1 (acetamiprid), 0.6 g L-1 (sulfoxaflor), and 0.875 g L-1 (deltamethrin). Further, we diluted the compounds in distilled water and tested them at 10%, 1%, and 0.1% of the field-recommended concentrations, and used distilled water as a control. We monitored the survival of the queens and the number of eggs laid. All three tested insecticides caused severe lethal and sublethal concentration-dependent effects. Even at concentrations three orders of magnitudes lower than recommended for field applications, significantly lower numbers of eggs were found in the queens' nests. The extent of the sublethal effects of acetamiprid and sulfoxaflor was concentration-dependent and differed between the two ant species. Besides bees and bumblebees, ants represent an important group of hymenopterans that are severely affected even by low concentrations of the tested compounds and therefore should be included in risk assessment schemes.

Claustral colony founding does not prevent sensitivity to the detrimental effects of azole fungicides on the fecundity of ants.

Azole fungicides (benzimidazoles, triazoles and imidazoles) are among the most widely used agrochemicals in the world. Unfortunately, azole fungicides are increasingly recognized for playing the role of endocrine disruptors in non-target organisms. Previously, the fecundity of ants with semi-claustral colony founding was found to be severely decreased in response to field-realistic concentrations of azole fungicides. However, during claustral colony founding, the ant queens do not feed and could therefore be protected against effects of agrochemicals applied during the colony founding. In the present study, we hypothesized that claustral colony founding is associated with a lower risk of oral exposure of ant queens to azole fungicides. We exposed queens of a common farmland ant species with claustral colony founding, Lasius niger, to four azole fungicides (epoxiconazole, flusilazole, prochloraz and thiophanate-methyl) that are commonly used in foliar applications and analyzed the differences in fecundity between fungicide-treated groups and the control water-treated group. We found that oral exposure to all four tested formulations of azole fungicides decreased the fecundity of L. niger queens. The decreases in fecundity ranged from 30.5% (epoxiconazole) to 40.3% (prochloraz), although the concentrations of fungicides used were several times lower than the minimum effective concentrations used to eliminate the target fungi by foliar applications of examined fungicides on various crops. Ants with both claustral and semi-claustral colony founding are highly vulnerable to field-realistic concentrations of azole fungicides that are sprayed in foliar applications. Azole fungicides substantially decrease the fitness of ant queens and may explain part of the recently observed decreases in farmland insect abundance and diversity.

Biodiversity in remnants of natural mountain forests under conservation-oriented management.

The structure of forests is an important stabilizing factor regarding ongoing global climate and land use change. Biodiverse mountain forests with natural structure are one of the ecosystems most endangered by these problems. We focused on the mountain forest islands of European beech (Fagus sylvatica) and their role in the natural distribution of organisms. The study area was situated in the oldest Czech national park, Krkonose (385 km2), which is the highest mountain ridge in the country. We studied multi-taxa (lichens, beetles and hymenopterans) responses to three hierarchical spatial levels of the environment: the topography was described by the elevation gradient; the patch structure was described by canopy openness, dead wood amounts, and Norway spruce (Picea abies) cover; and the tree level was described by species of the sampled tree and its diameter. Lichens preferred higher elevations, while insect groups responded conversely. Furthermore, insect groups were mainly influenced by the inner patch structure of beech islands. Lichens may be jeopardized due to the predicted future increase in temperatures, since they would need to shift toward higher altitudes. Insects may be mainly threatened in the future by land use changes (i.e., forest management) - as indicated by an interconnection of canopy openness and the amount of dead wood.

Forecasting SPEI and SPI Drought Indices Using the Integrated Artificial Neural Networks.

The presented paper compares forecast of drought indices based on two different models of artificial neural networks. The first model is based on feedforward multilayer perceptron, sANN, and the second one is the integrated neural network model, hANN. The analyzed drought indices are the standardized precipitation index (SPI) and the standardized precipitation evaporation index (SPEI) and were derived for the period of 1948-2002 on two US catchments. The meteorological and hydrological data were obtained from MOPEX experiment. The training of both neural network models was made by the adaptive version of differential evolution, JADE. The comparison of models was based on six model performance measures. The results of drought indices forecast, explained by the values of four model performance indices, show that the integrated neural network model was superior to the feedforward multilayer perceptron with one hidden layer of neurons.

Benomyl treatment decreases fecundity of ant queens.

Methyl benzimidazole carbamate fungicides, including benomyl, are widely used in agriculture, and to eliminate entomopathogenic infections. We treated queens of Myrmica rubra (Hymenoptera:Formicidae) infected or not by Rickia wasmannii (Laboulbeniales:Laboulbeniaceae) with benomyl, 1mg/ml p.o. for six weeks. Benomyl did not treat the infection, and the treatment alone caused strong decrease in the fecundity of control healthy queens from 18.0±8.4 to 3.7±5.2eggs per healthy queen. This is the first evidence on severe adverse effects of methyl benzimidazole carbamate fungicide on the fecundity of insects, which might be responsible for altered species composition of ant assemblages in the cultural landscape.

Physiological and biochemical responses to cold and drought in the rock-dwelling pulmonate snail, Chondrina avenacea.

The pulmonate snail Chondrina avenacea lives on exposed rock walls where it experiences drastic daily and seasonal fluctuations of abiotic conditions and food availability. We found that tolerance to dry conditions was maintained at a very high level throughout the year and was mainly based on the snails' ability to promptly enter into estivation (quiescence) whenever they experienced drying out of their environment. Snails rapidly suppressed their metabolism and minimized their water loss using discontinuous gas exchange pattern. The metabolic suppression probably included periods of tissue hypoxia and anaerobism as indicated by accumulation of typical end products of anaerobic metabolism: lactate, alanine and succinate. Though the drought-induced metabolic suppression was sufficient to stimulate moderate increase of supercooling capacity, the seasonally highest levels of supercooling capacity and the highest tolerance to subzero temperatures were tightly linked to hibernation (diapause). Hibernating snails did not survive freezing of their body fluids and instead relied on supercooling strategy which allowed them to survive when air temperatures dropped to as low as -21 °C. No accumulation of low-molecular weight compounds (potential cryoprotectants) was detected in hibernating snails except for small amounts of the end products of anaerobic metabolism.

Phylogeny of Maculinea blues (Lepidoptera: Lycaenidae) based on morphological and ecological characters: evolution of parasitic myrmecophily.

A phylogeny of blue butterflies of the genus Maculinea and related genera (Lycaenidae) is proposed, based on 91 morphological and ecological characters. The resulting tree shows that: (1) Phengaris is a derived group nested within Maculinea; (2) the Maculinea-Phengaris clade is probably nested within Glaucopsyche; (3) there are three well supported groups within the Maculinea-Phengaris clade: (alcon group ((teleius group) (arion-Phengaris group))). Some species (M. alcon, M. arionides) appear to be non-monophyletic and require reclassification. The two alternative strategies of parasitic myrmecophily in the Maculinea-Phengaris clade, viz., "predatory" and "cuckoo", seem to be derived characters of the alcon group, and of the teleius and arion-Phengaris groups, respectively. The common ancestor of Maculinea used dorsal nectary organ secretions for ant attraction, while this trait was reduced in the ancestor of the alcon group and in M. nausithous (of the teleius group). The three recent Maculinea lineages utilize taxonomically diverse host plants, the asterid families Gentianaceae (alcon and arion-Phengaris groups), Lamiaceae (arion-Phengaris group), Campanulaceae (arion-Phengaris group), and the rosid family Rosaceae (teleius group).