Fir decline and mortality in the southern Siberian Mountains

Regional Environmental Change - Increased dieback and mortality of “dark needle conifer” (DNC) stands (composed of fir (Abies sibirica), Siberian pine (Pinus sibirica) and spruce (Picea...     

Dynamic trends of heavy metal contents in plants and soil under different industrial air pollution regimes

Based on 30-year monitoring of Ni²⁺ and Cu²⁺ concentrations in the organic horizon of Albic Rustic Podzols and the foliage of six plant species, a dynamic trend in the level of heavy metal accumulation in the components of forest ecosystems of the Kola Peninsula has been revealed against the background of five- to eightfold reduction of pollutant emissions. The direction of the trend has been found to differ: the size of polluted area and pollution level increase with time, while the concentrations of heavy metals in plants decrease due to reduction in their input from the polluted air.     

Siberian musk deer in the diets of tiger and bears in the Sikhote-Alin

The role of the Siberian musk deer in the diets of the Amur tiger, brown bear, and Asian black bear has been studied in the Sikhote-Alin State Biosphere Reserve in 1992 to 2016. Information has been collected from 763 tiger feeding sites, and the contents of tiger feces have been analyzed. Radiotelemetry has been used to evaluate tiger–musk deer relationships. The musk deer accounted for 0.26% of all animal species found to be eaten by the tiger. Musk deer remains in feces of the tiger, brown bear, and Asian black bear occurred with frequencies of 1.3, 0.2, and 0.3%, respectively. A case of musk deer avoiding the presence of brown bear is described.     

Development of vegetative and generative organs in magnetic orientation types of radish in a weak permanent magnetic field

Experiments have been performed to evaluate the impact of weak permanent horizontal magnetic field of about 400 A/m on seed formation in the main magnetic orientation types of radish, the north-south (NS) and west-east (WE) types. The results show that external magnetic field exposure retards plant progression through all stages of ontogeny but does not alter the ratio of NS and WE types. Under its effect, the numbers of pods and seeds and seed weight decrease in the NS-type but increase in the WS-type plants. Therefore, external magnetic field acts as an ecological factor that differentiates the responses of radish plants depending on the type of their magnetic orientation. Differences in the sensitivity of plants to magnetic field exposure are explained by specific features of their physiological status.     

The New Zealand experience of varroa invasion highlights research opportunities for Australia

The Varroa mite (Varroa destructor) is implicated as a major disease factor in honey bee (Apis mellifera) populations worldwide. Honey bees are extensively relied upon for pollination services, and in countries such as New Zealand and Australia where honey bees have been introduced specifically for commercial pollinator services, the economic effects of any decline in honey bee numbers are predicted to be profound. V. destructor established in New Zealand in 2000 but as yet, Australia remains Varroa-free. Here we analyze the history of V. destructor invasion and spread in New Zealand and discuss the likely long-term impacts. When the mite was discovered in New Zealand, it was considered too well established for eradication to be feasible. Despite control efforts, V. destructor has since spread throughout the country. Today, assessing the impacts of the arrival of V. destructor in this country is compromised by a paucity of data on pollinator communities as they existed prior to invasion. Australia’s Varroa-free status provides a rare and likely brief window of opportunity for the global bee research community to gain understanding of honey bee-native pollinator community dynamics prior to Varroa invasion.     

Phenotypic variation and adaptive reaction to the presence of predator in two Daphnia species (Daphniiformes, <Emphasis Type="Italic">Daphnia</Emphasis>) in Lake Baikal

The effect of invertebrate predation pressure by the cladoceran Leptodora kindti on the population structure of Daphnia galeata and D. hyalina has been estimated by analyzing the occurrence frequency of the normal and spined morphotypes in Lake Baikal. It is shown that the growth of L. kindti population density leads to an increase in the proportion of the spined morphotype, while that of that of the normal morphotype decreases.     

Effects of agricultural pesticides on the health of Rana pipiens frogs sampled from the field

There is evidence that over the last 30 years, there have been mass declines in diverse geographic locations among amphibian populations due to disease outbreaks. Multiple causes have been suggested to explain this increase in disease incidence. Among these, climate changes, environmental pollution and reduced water quality are gaining attention. Indeed, some chemicals of environmental concerns are known to alter the immune system. It is possible that exposure to these pollutants could alter the immune system of anurans and render them more susceptible to different pathogens. In this study, we sampled Rana pipiens in five different sites near St. Lawrence River (Quebec, Canada) during the months of July and September in 2001. Two of these sites were protected areas, in which low levels of pesticides were detected, while the remaining three sites were located in areas with intensive corn and soybeans cultivations. Our results demonstrated that frogs living in agricultural regions are smaller in size and weight than frogs living in areas with lower levels of pesticides at both sampling times. Moreover, we have observed a significant decrease in the number of splenocytes (cellularity) and the phagocytic activity in frogs sampled in impacted sites. Taken together, these results suggest that frogs living in agricultural regions might be more vulnerable to infections and diseases through their smaller size and alteration of their immune system. Our results also contribute to the overall discussion on factors involved in amphibian declines.     

Beyond selectivity: Are behavioral avoidance and hormesis likely causes of pyrethroid-induced outbreaks of the southern red mite Oligonychus ilicis?

Secondary pest outbreak is a counterintuitive ecological backlash of pesticide use in agriculture that takes place with the increase in abundance of a non-targeted pest species after pesticide application against a targeted pest species. Although the phenomenon was well recognized, its alternative causes are seldom considered. Outbreaks of the southern red mite Oligonychus ilicis are frequently reported in Brazilian coffee farms after the application of pyrethroid insecticides against the coffee leaf miner Leucoptera coffeella. Selectivity favoring the red mite against its main predatory mites is generally assumed as the outbreak cause, but this theory has never been tested. Here, we assessed the toxicity (and thus the selectivity) of deltamethrin against both mite species: the southern red mite and its phytoseid predator Amblyseius herbicolus. Additionally, behavioral avoidance and deltamethrin-induced hormesis were also tested as potential causes of red mite outbreak using free-choice behavioral walking bioassays with the predatory mite and life-table experiments with both mite species, respectively. Lethal toxicity bioassays indicated that the predatory mite was slightly more susceptible than its prey (1.5×), but in more robust demographic bioassays, the predator was three times more tolerant to deltamethrin than its prey, indicating that predator susceptibility to deltamethrin is not a cause of the reported outbreaks. The predator did not exhibit behavioral avoidance to deltamethrin; however insecticide-induced hormesis in the red mite led to its high population increase under low doses, which was not observed for the predatory mite. Therefore, deltamethrin-induced hormesis is a likely cause of the reported red mite outbreaks.