Growth and development of winter tick, Dermacentor albipictus, on moose, Alces alces

Moose, Alces alces, were infested with 21,000 or 42,000 larval Dermacentor albipictus at the end of September. Larvae grew rapidly and molted to the nymphal stage 10-22 days after infestation. The nymphal stage lasted approximately 3 mo until mid-January and was characterized by a diapause. The diapause is likely an adaptation to survival in cold climates. Nymphs started engorging in January and adults were seen with increasing abundance from mid-January to March and April. The minimum parasitic period was 175 days. Growth of larvae and nymphs was similar on moose given different numbers of larvae and was generally similar between a moose infested in November and moose infested earlier. Dimensions and stages of development throughout the parasitic phase are given. Game enforcement officers are encouraged to use these data for determination of season of death of moose.     

Choice of feeding sites by moose during summer, the influence of forest structure and plant phenology

We observed forage and habitat selection in radio-collared moose at feeding sites in southeast Norway. Use of older forest increased from spring to autumn. Birch Betula spp. and bilberry Vaccinium myrtillus accounted for c. 75% of the diet. Occurrence of important forage plants, height of browse, and difference in phenology between plant species all appeared to play a role in moose selection of feeding sites. Shading influences moose forage by delaying plant phenology and possibly through its effect on leaf content of water and secondary compounds. On single birch trees, feeding was concentrated to the top branches at midsummer; during spring and autumn more leaves from side branches were eaten. Greater discrimination as vegetation matured was also evident from the wider variety of forage species used at midsummer. Selection of feeding sites was not related to density of important browse species. We propose that variations in light/shade conditions may play a role in moose choice of feeding sites and that moose on summer range will benefit from a heterogeneous mixture of plantations and older forest stands.     

Quantitative short-day photoperiodic response in larval development and its adaptive significance in an adult-overwintering cerambycid beetle, Phytoecia rufiventris

The chrysanthemum longicorn beetle, Phytoecia rufiventris, overwinters in the adult stage and reproduces in spring. Larvae of this beetle develop during summer inside a host stem or root. In the present study, photoperiodic control of larval development and its adaptive significance were examined in this beetle using an artificial diet. Larvae showed a short-day photoperiodic response at 25 °C with a critical day length of around 14 h; larvae reared under short-day conditions pupated, whereas those reared under long-day conditions entered summer diapause with some supernumerary molts and did not pupate. A similar response was found at 30 °C, but with a shorter critical day length. Below the critical day length, a shorter day length corresponded to a shorter larval period. Larvae transferred from long-day conditions to various photoperiods showed a similar quantitative response. Field rearing of larvae starting at various times of year showed that pupation occurs within a relatively short period in early autumn. Field rearing of pupae and adults at various times indicated that only pupation in early autumn results in a high survival rate until winter. Earlier or later pupation led to a low survival rate due to death before overwintering in the adult and pupal stages, respectively. Thus, in P. rufiventris, timing of pupation regulated by the quantitative short-day photoperiodic response is vital for survival. Relatively lower developmental threshold in the pupal stage supports this hypothesis.     

Studies on the ecology of Haemaphysalis silacea Robinson 1912 (Acarina: Ixodidae).

Haemaphysalis silacea Robinson is known to be established only in the Eastern Cape Province of South Africa, in localized areas of Fish River Bush in the river valleys and in the coastal bush complex. In the Kowie River valley, it was shown that the distribution of larvae is limited by microclimatic conditions. The humid leaf litter zone in the dense vegetation on the river banks and along minor tributaries is the focus of the larval population. Nymphs are most numerous in drier microhabitats on the wooded, river floodplain. Larvae are active during the humid conditions of autumn and early winter, nymphs during late winter and spring, and adults during the hot, dry summer months. The main hosts of H. silacea are artiodactyls, which are numerous in the dense Fish River Bush. The host/tick interaction occurs as a result of the daily movements and feeding habits of the hosts.     

Moose density and habitat productivity affects reproduction,growth and species composition in field layer vegetation

Question: What is the effect of a gradient in moose density on reproduction, growth and functional composition of the field layer vegetation in a boreal forest, and how is this effect modified by habitat productivity? Location: Northwest of Umeå, Västerbotten, northern Sweden. Methods: Field layer vegetation was surveyed in an experimental setup with simulation of three different moose densities and a control in eight study sites along a gradient of habitat productivity. Results: We found that increased moose density led to decreased cover and reproductive effort of a browsed dwarf shrub (bilberry, Vaccinium myrtillus L.) and increased cover and reproductive effort of a non‐browsed graminoid (wavy hair‐grass, Avenella flexuosa (L.) Drejer). Increased moose density led to increased light availability and probably reduced competition from V. myrtillus. Total reproductive effort in the field layer vegetation increased, height decreased and cover of light‐demanding species and graminoids increased with increasing moose density. The effects of moose density were modified by the productivity gradient, leading to a higher relative increase in light availability and reproductive effort in highly productive areas than in low productive areas. Conclusions: Increased light availability was an important indirect effect of moose density, leading to less competition for light and a shift towards early successional species. The effect of moose density on light availability was modified by habitat productivity, leading to stronger relative effects in highly productive areas than in low productive areas.     

Behavioral Adaptations of Moose to Roadside Salt Pools

Abstract: Sodium has many fundamental physiological functions in animals but is rare in boreal ecosystems where moose (Alces alces) thrive. In Québec (Canada), sodium is readily available in aquatic vegetation and in salt pools that form along highways. We do not know if moose are adopting specific behaviors to access sodium sources or if they simply use the sodium sources they encounter during their movements. We tested the hypothesis that moose modify both space and habitat use to gather sodium from salt pools. We expected moose to use salt pools mostly in spring and early summer, when needs are greatest and before aquatic vegetation has fully developed. We fitted 47 moose with Global Positioning System telemetry collars and collected data for 2 to 36 months between 2003 and 2006. We rarely located moose at salt pools (0.12% among the 95,007 locations collected). As we expected, use of salt pools was highest in late spring and in early summer, and we observed a time lag between peak use of salt pools compared to use of lakes and waterways, indicating moose fulfilled their sodium requirements in salt pools before aquatic vegetation was available. Moose selected salt pools over lakes and waterways when these 2 sodium sources were present in their home range and moved rapidly over large distances to reach them. Our results were consistent with moose using salt pools when they are likely to be sodium deficient. Salt pools were less accessible, required long-distance movements, and were located in habitually avoided areas along highways. Elimination of roadside salt pools should be considered among strategies to reduce cervid-vehicle collision risks in boreal environments.     

Effects of predator treatments,individual traits,and environment on moose survival in Alaska

We studied moose (Alces alces) survival, physical condition, and abundance in a 3-predator system in western Interior Alaska, USA, during 2001–2007. Our objective was to quantify the effects of predator treatments on moose population dynamics by investigating changes in survival while evaluating the contribution of potentially confounding covariates. In May 2003 and 2004, we reduced black bear (Ursus americanus) and brown bear (U. arctos) numbers by translocating bears ≥240 km from the study area. Aircraft-assisted take reduced wolf (Canis lupus) numbers markedly in the study area during 2004–2007. We estimated black bears were reduced by approximately 96% by June 2004 and recovered to within 27% of untreated numbers by May 2007. Brown bears were reduced approximately 50% by June 2004. Late-winter wolf numbers were reduced by 75% by 2005 and likely remained at these levels through 2007. In addition to predator treatments, moose hunting closures during 2004–2007 reduced harvests of male moose by 60% in the study area. Predator treatments resulted in increased calf survival rates during summer (primarily from reduced black bear predation) and autumn (primarily from reduced wolf predation). Predator treatments had little influence on survival of moose calves during winter; instead, calf survival was influenced by snow depth and possibly temperature. Increased survival of moose calves during summer and autumn combined with relatively constant winter survival in most years led to a corresponding increase in annual survival of calves following predator treatments. Nonpredation mortalities of calves increased following predator treatments; however, this increase provided little compensation to the decrease in predation mortalities resulting from treatments. Thus, predator-induced calf mortality was primarily additive. Summer survival of moose calves was positively related to calf mass (β > 0.07, SE = 0.073) during treated years and lower (β = −0.82, SE = 0.247) for twins than singletons during all years. Following predator treatments, survival of yearling moose increased 8.7% for females and 21.4% for males during summer and 2.2% for females and 15.6% for males during autumn. Annual survival of adult (≥2 yr old) female moose also increased in treated years and was negatively (β = −0.21, SE = 0.078) related to age. Moose density increased 45%, from 0.38 moose/km² in 2001 to 0.55 moose/km² in 2007, which resulted from annual increases in overall survival of moose, not increases in reproductive rates. Indices of nutritional status remained constant throughout our study despite increased moose density. This information can be used by wildlife managers and policymakers to better understand the outcomes of predator treatments in Alaska and similar environments. © 2011 The Wildlife Society.     

Life cycle of an endangered riffle beetle,Leptelmis gracilis Sharp (Coleoptera: Elmidae), in the Hiikawa River system,Shimane prefecture,Japan

We studied the life cycle of the riffle beetle Leptelmis gracilis Sharp, 1888 from a population located in a river stream with lotic environments. Samples were collected monthly, between September 2018 and August 2019, from a tributary of the Hiikawa River in Izumo city, Shimane Prefecture, Honshu, Japan. Larvae were separated into five distinct groups based on size. The first and last instar larval sizes were identified through rearing methods. From these results, we determined that the larval stage of this species consists of five instars. From the monthly evaluations, the number of individuals corresponding to each instar period suggested that last-instar larvae were dominant in May and that new adults emerged from July to August. Landing and pupation were estimated to occur from May to June. Monthly observations revealed that mature eggs were present in the female abdomen from April to June, as well as from August to September. It is, therefore, predicted that overwintering adults mainly oviposit from spring to early summer, while new adults oviposit from late summer to early autumn.     

Effect of Roadside Vegetation Cutting on Moose Browsing

Moose (Alces americanus ) vehicle collisions (MVCs) are an issue throughout the distribution of moose. Many mitigation strategies have been tested and implemented to reduce the number of MVCs, but there have been few empirical analyses of the effectiveness of roadside vegetation cutting. The goal of this study was to determine if roadside vegetation cutting attracted moose into roadside areas to browse on the vegetation regrowth. We hypothesized that moose would be attracted to roadside areas with cut vegetation. Consequently, we predicted that there would be higher levels of browsing in cut areas compared to uncut areas. To determine if moose were browsing more in cut or uncut areas, we measured the number of plants browsed by moose in paired treatment (cut on or after 2008) and control (not cut since at least 2008) sites, along with a suite of potential environmental covariates. Using a model selection approach, we fit generalized linear mixed-effects models to determine the most parsimonious set of environmental variables to explain variation in the proportion of moose browse among sites. In contrast to our hypothesis, our results show that the proportion of moose browse in the uncut control areas was significantly higher than in the cut treatment areas. The results of this study suggest that recently cut roadside areas (7 years or less based on our work) may create a less attractive foraging habitat for moose. The majority of the variance in the proportion of moose browse among sites was explained by treatment type and nested plot number within site identification (34.16%), with additional variance explained by traffic region (5.00%) and moose density (4.35%). Based on our study, we recommend that vegetation cutting be continued in roadside areas in Newfoundland as recently cut areas may be less attractive browsing sites for moose.     

Population characteristics predict responses in moose body mass to temporal variation in the environment

1. A general problem in population ecology is to predict under which conditions stochastic variation in the environment has the stronger effect on ecological processes. By analysing temporal variation in a fitness-related trait, body mass, in 21 Norwegian moose Alces alces (L.) populations, we examined whether the influence of temporal variation in different environmental variables were related to different parameters that were assumed to reflect important characteristics of the fundamental niche space of the moose. 2. Body mass during autumn was positively related to early access to fresh vegetation in spring, and to variables reflecting slow phenological development (low June temperature, a long spring with a slow plant progression during spring). In contrast, variables related to food quantity and winter conditions had only a minor influence on temporal variation in body mass. 3. The magnitude of the effects of environmental variation on body mass was larger in populations with small mean body mass or living at higher densities than in populations with large-sized individuals or living at lower densities. 4. These results indicate that the strongest influence of environmental stochasticity on moose body mass occurs towards the borders of the fundamental niche space, and suggests that populations living under good environmental conditions are partly buffered against fluctuations in environmental conditions.     

The biology of Brachycentrus subnubilus Curtis (Trichoptera) in the River Frome,Dorset

Aspects of life-history, oviposition and microdistribution within beds of Ranunculus penicillatus var. calcareus (R. W. Butcher) C.D.K. Cook are considered. Brachycentrus subnubilus Curtis has one generation each year, with five larval instars. Larvae favour sites beneath the weedbeds for most of the year, migrating to more exposed areas in the spring to pupate. Pupation, emergence, oviposition and eclosion are completed in just over two months. Eggs are usually laid on submerged marginal vegetation but any semi-submerged object may be utilized. Larvae appear to disperse mainly as first instars; in this they are likely to be seriously affected by weedcutting activities. Initial development is rapid to fourth instar. Larvae overwinter as fifth instars. Sex ratios show a predominance of males.     

小兴安岭黑河胜山林区冬季驼鹿的生境选择

2002年、2003年和2004年的12月至3月,在小兴安岭黑河胜山林场开展了驼鹿生境选择的研究。研究中选择了9类与驼鹿生境选择相关的生态因子：植被型、离公路距离、离采伐点距离、平均雪深、隐蔽程度、坡向、坡位、坡度、海拔,运用SPSS软件进行交叉汇总定量分析。结果表明,胜山驼鹿冬季以落叶阔叶林、灌丛为主要生境,影响驼鹿分布的主要生态因子为隐蔽程度、坡位,其次为雪深、坡向、离采伐点距离、离公路距离,坡度、海拔对驼鹿分布的影响不明显。     

Taxonomic composition and distribution of Euphausiacea and Decapoda (Crustacea) in the neuston of the Bay of Fundy, Canada

The taxonomic composition and geographic distribution of Euphausiaceaand Decapoda occurring in the neu.ston were examined in spring,summer and autumn surveys of a 2.4x10⁴ km² area of the Bay ofFundy. Adult Meganyctiphanes norvegica and Thysanoessa inermis(Euphausiacea) were present in every survey and were most abundantin autumn. Larval euphausiids were most abundant in summer butwere also present in spring and autumn. Adults of three natantiandecapod species were rarely collected; however, larval Natantiawere common in summer and autumn. Larvae representing sevengenera of reptantian decapods were collected in summer and autumn;the most abundant was Cancer sp., which was numerically dominantin summer samples. Distributional patterns divide the taxa intoinner and outer bay components at a line drawn between Digby,Nova Scotia and St John, New Brunswick, corresponding to theboundary of the major counterclockwise gyre in the Bay of Fundy.     

Effects of dietary variation on growth,composition, and maturation of Manduca sexta (Sphingidae: Lepidoptera)

Most studies linking dietary variation with insect fitness focus on a single dietary component and late larval growth. We examined the effects of variation in multiple dietary factors over most life stages of the sphingid moth, Manduca sexta. Larvae received artificial diets in which protein, sucrose, and water content were varied. The relationship between larval size, growth and consumption rates differed significantly across diets. Larvae on control and low-sucrose diets grew most rapidly and attained the largest pupal and adult sizes. Conversely, larvae on low-water and low-protein diets initially grew slowly, but accelerated in the fifth instar and became pupae and adults comparable to control animals in size. There were no fundamental differences in protein:carbohydrate consumption patterns or strategies among experimental diets and larval instars. However, inadequate dietary water appeared to be more important for early than late instar larvae. Larvae on all artificial diets showed increasing fat content throughout all stages, including wandering and metamorphosis. Compensatory feeding among low-water and low-protein larvae was correlated with significantly higher fat content in larvae, pupae and adults, whereas low-sucrose animals were substantially leaner than those on the control diet. These differences may have strong effects on adult physiology, reproduction, and foraging patterns.     

Behavior of Moose Relative to a Road Network

Abstract Roads often negatively affect terrestrial wildlife, via habitat loss or fragmentation, noise, and direct mortality. We studied moose (Alces alces) behavior relative to a road network, in an area with a history of moose-vehicle accidents, to determine when moose were crossing roadways or using areas near roads and to investigate if environmental factors were involved in this behavior. We tracked 47 adult moose with Global Positioning System collars in a study area crossed by highways and forest roads. We hypothesized that moose would avoid crossing roads but would make occasional visits to roadsides to feed on sodium-rich vegetation and avoid biting insects. Further, we expected moose avoidance to be greater for highways than forest roads. We recorded 196,710 movement segments but only observed 328 highway and 1,172 forest-road crossings (16 and 10 times lower than expected by chance). Moose usually avoided road proximity up to ≥500 m on each side but 20% of collared moose made visits to areas within 50 m of highways, which might have resulted from moose searching for sodium in vegetation and roadside salt pools. In fact, vegetation along highways had higher sodium concentrations and was browsed in similar proportions to vegetation in adjacent forest, despite moose avoidance of these zones. Moose, however, did not use areas near roads more during periods of biting insect abundance. Our results supported the hypothesis of scale-dependent selection by moose; avoidance of highways at a coarse scale may confer long-term benefits, whereas selection of highway corridors at finer scales may be part of a strategy to overcome short-term limiting factors such as sodium deficiency. We found a positive relationship between home-range size and the proportion of road axes they contained, suggesting that moose either compensated for habitat loss or made specific movements along highways to gather sodium. The presence of sodium along highways likely increases moose-vehicle accident risks. Removal of salt pools or use of a de-icing salt other than sodium chloride should render highway surroundings less attractive to moose.     

Synchrony in short-term fluctuations of moose calf body mass and bank vole population density supports the mast depression hypothesis

Inter-annual variations in body mass of moose, Alces alces , in Norway and Sweden have been considered as most likely due to direct or indirect effects of weather, but so far predictions of autumn body mass of moose calves on the basis of weather data have given a poor fit to data. A striking, but hitherto unnoticed, feature of several time series on body mass of moose calves from south-eastern Norway is an apparently regular 3–4-year fluctuation pattern. This short-term fluctuation could be due to regular variations in forage quality, e.g. caused by a cyclic seed production of some important food plants, as envisaged by the "mast depression" hypothesis. One plant species important as food for moose calves in autumn is bilberry, Vaccinium myrtillus , which usually produces high seed crops (masts) at intervals of 3–4 years. Populations of the bank vole, Clethrionomys glareolus, which feeds on bilberry shoots in winter, are known to peak in bilberry post-mast years. In two study areas in Norway, there was a positive correlation between the autumn body mass of moose calves and the autumn population index of bank vole in the succeeding year. In the northern area there was an additional positive effect of summer precipitation, whereas in the southern area there was an additional negative effect of summer temperature. In both areas, however, the effect of weather was less pronounced than that of the bank vole index. These results support the mast depression hypothesis.     

Differences in urinary chemistry profiles of moose on Isle Royale during winter

During winters 1987-1988 (I) and 1988-1989 (II), we assessed the physiological status of moose (Alces alces) residing on the west and east ends of Isle Royale (Michigan, USA) by collecting and chemically analyzing urine deposited in snow (snow-urine) from January to early March. Samples were assayed for urea nitrogen (U), sodium (Na), potassium (K), calcium (Ca), phosphorus (P) and creatinine (C). Throughout both winters, elevated urinary U:C ratios in snow-urine samples collected from east-end moose compared to west-end moose indicated greater dietary energy deprivation and accelerated net catabolism of endogenous protein. Sodium: C ratios were low throughout the study and were similar between moose from both ends of the island, except during the middle of winter I. Greater K:C, P:C and Ca:C ratios in east-end moose compared to west-end moose throughout winter I, and increases in these ratios and U:C in east-end moose from middle to late winter during the second year provided additional evidence of a greater deterioration in condition in east-end moose. The superior nutrition provided to moose on the west end of the island was associated with more developed soils and diverse vegetation and a lower stem density of balsam fir compared to the east end.     

Effect of ultraviolet radiation on growth and percent settlement of larval Lytechinus variegatus (Echinodermata: Echinoidea)

Lytechinus variegatus larvae were used to examine the effects of ecologically relevant short-term exposures of ultraviolet radiation (UVR) on larval morphology and settlement. A laboratory experiment tested the blastula, gastrula, and early pluteus stages of larval development for susceptibility to damage from exposure to UVR produced by an artificial light source. Larval post-oral arm length and percent settlement were measured to assess UVR effects. Larvae exposed at the blastula and gastrula stages had a reduction in larval post-oral arm length compared with non-exposure controls, while larvae exposed at the early pluteus stage were similar to controls. Larvae exposed in the gastrula stage had a significant reduction in percent settlement compared with controls. Negative consequences from ecologically relevant levels of UVR were differentially dependent on the larval stage at time of exposure suggesting time point in larval development at exposure will be important in interpreting effects on higher levels of biological organization.     

Growth and development of Australian soldier fly,Inopus rubriceps (Diptera: Stratiomyidae), in New Zealand

Abstract

Larvae of Inopus rubriceps (Macquart) were reared from eggs originating from spring and autumn adult emergence periods (1975–78), under both insectary and field conditions. Rate of development appeared to depend largely on temperature. Autumn-hatched larvae showed little growth for the initial 6 months, but then grew rapidly until the end of summer. Spring-hatched larvae also grew rapidly over summer, but their development slowed over winter. Year-to-year differences were found in larval survival, weight gain, and rate of development, and in subsequent adult emergence. Pest status appeared to be related to the cumulative yearly heat budget. Overall, larval survival was higher and growth and development were more rapid in the insectary than under field conditions. A male-dominant sex ratio was demonstrated.     

Photoperiodic effect on size-related metamorphosis in the milkweed leaf beetle, Labidomera clivicollis

ABSTRACT. Photoperiod significantly affected size-related aspects of metamorphosis in the milkweed leaf beetle Labidomera clivicollis (Kirby) (Chrysomelidae). Larvae reared under short-day photoperiod successfully pupated at lower weights than larvae reared under long-day photoperiods. This short-day effect was observed to an equivalent extent in both males and females; but within photoperiod treatments, males consistently pupated at lower weights than females. It is likely that the short-day effect on metamorphosis is associated with photo-periodically induced changes in larval corpora allata activity or juvenile hormone titre. Ecologically, the short-day effect on metamorphosis may enhance the moulting success of larvae which encounter food shortages during autumn.