Effect of tillage on abundance of Japanese beetle, Popillia japonica Newman (Col., Scarabaeidae), larvae and adults in highbush blueberry fields

Abstract:  At 15 commercial highbush blueberry farms, fields where row middles were tilled had 72% lower larval density of Popillia japonica than fields with grass in row middles. Popillia japonica larval populations were similar in the perimeters of tilled and untilled fields. Soil parameters measured in these sites were not correlated with larval density of P. japonica. Samples of adult beetles on bushes showed that they were significantly less abundant in tilled fields compared with fields with grass in the row middles. The abundance of larvae inside fields during the spring was significantly correlated with early, but not late summer abundance of adult beetles on bushes. Comparisons of different tillage timings showed that grassy plots between rows of blueberry bushes that were tilled in spring and kept bare all year round had lower abundance of P. japonica larvae than those that retained perennial ryegrass. The effect of tillage timing on larval abundance was not consistent across 2 years, but most timings caused similar reduction in P. japonica larval density in the row middles. Tillage in the spring and in the autumn caused 50.5% and 68.8% reduction of larval density in each year respectively. These results indicate that tillage can reduce P. japonica larval and adult abundance in highbush blueberry fields.     

Testosterone and autumn territorial behavior in male red grouse Lagopus lagopus scoticus

In many bird species, males exhibit territorial aggression outside the breeding season, when testosterone concentrations are low and may not regulate territorial behaviors. The hormonal regulation of aggression at this time of year has only been studied in passerine birds. Here, we investigated the role of testosterone in the regulation of aggression in a non-passerine bird, the red grouse Lagopus lagopus scoticus. Male red grouse are aggressive in early spring when breeding starts, in autumn when they establish territories, and sporadically through much of the winter. We first describe seasonal variations in plasma testosterone concentrations and in the size of males' sexual ornaments, their red combs, which relates to aggressiveness. Testosterone concentrations and comb size were correlated. Both increased in autumn to a peak in October, and then increased again in spring, to a greater peak in early April. Secondly, we experimentally investigated the effects of testosterone, and of an anti-androgen (flutamide) used in combination with an aromatase inhibitor (ATD), on autumn territorial behavior. Males were treated with either empty implants, as controls (C-males), testosterone implants (T-males), or with flutamide and ATD implants (FA-males). One month after implanting, both T- and FA-males had higher concentrations of testosterone than C-males. Comb size, aggressive call rate, and response to playbacks of territorial call all significantly increased in T-males. However, the increase in testosterone in FA-males did not increase comb size or aggressive behavior. In the following spring, after the content of implants was used, FA-males had significantly lower testosterone than C-males, and had a reduced seasonal increase in comb size. The results suggest that testosterone plays a significant role in regulating red grouse aggressive behavior in autumn. However, the observation that flutamide and ATD treatment did not reduce territorial behavior, suggests that estradiol may also be involved in the regulation of non-breeding aggression.     

Seasonal variations in feeding range and flock structure of the Rook Corvus frugilegus in eastern Ireland

The feeding range and flock structure of Rooks showed temporal variations caused mainly by the dispersion of food and reproductive behaviour.
Feeding range was restricted in spring, autumn and early winter when food availability was high and Rooks were reproductively active. A large feeding range occurred in late summer and late winter, when food availability was either generally low or locally distributed and when Rooks were reproductively inactive. The occurrence of flocks common to several rookeries mirrored variations in feeding range; mixed rookery flocks were more common in late summer and late winter. Similarly, the size of the rookery (as measured by the number of nests) was related to feeding range only when Rooks were reproductively inactive and at such times larger rookeries had greater feeding ranges.
Flock structure showed similar seasonal variations; small widely spaced flocks predominated in summer, autumn, early winter and spring, whereas large dense flocks occurred in late winter. Diurnal variations in flock structure occurred within any one season. Both seasonal and diurnal variations in flock structure may be determined by the dispersion of the prey and the feeding strategy used to obtain it, reproductive behaviour and the risk of predation.     

The adult body size variation of Dryas iulia (Lepidoptera,Nymphalidae, Heliconiinae) in different populations is more influenced by temperature variation than by host‐plant availability during the seasons

The body size of insects is affected by environmental conditions during development and can present considerable intraspecific variations, which can be seen as an ultimate consequence/adaptation to environmental conditions. This paper evaluated whether the body size of the butterfly Dryas iulia from subtropical populations was influenced by changing climate conditions and food source availability during the seasons. The likely reasons behind body size variation were also investigated. First, field data on body size variation, host‐plant availability and climate fluctuation throughout the seasons were recorded. Then, the effects of host‐plant species and temperature on body size were analyzed by controlled experiments. Field data revealed that body size and host‐plant availability varied significantly through the seasons. Populations had the smallest body size during the spring and the biggest size during summer, whereas host‐plant availability was lower during winter and higher during spring. The controlled experiments revealed that both temperature and host‐plant had significant effect on the plasticity of body size. Larvae subjected to winter temperature treatment led to smaller butterflies when compared to immatures reared under summer temperature treatment, and larvae fed with Passiflora misera produced bigger adults when compared to larvae reared on Passiflora suberosa. The combination of data gathered in the field and in the laboratory suggests that seasonal body size variation in D. iulia is related mainly to differences in the temperatures to which larvae are subjected during development, while host‐plant shifts caused by differential availability of food through the seasons had slightly effects on the variation observed.     

施肥对蓝莓植株生长、叶片叶绿素荧光特性和果实品质的影响

以蓝莓“美登”为试验材料,在我国大兴安岭地区研究了连续3年施肥对蓝莓植株生长、叶片叶绿素荧光参数以及果实品质的影响,为优化我国北方地区蓝莓人工栽培技术提供一些基础数据。结果表明：施肥处理可以明显促进蓝莓植株的生长,7.5 g/株施肥量对蓝莓株高和冠幅度的促进作用最明显,而不同施肥量对蓝莓枝条长度和粗度的影响差异不明显。施肥处理还明显促进了蓝莓叶片的实际光化学效率和电子传递速率,以及PSⅡ反应中心的开放程度,并且施肥处理下蓝莓叶片PSⅡ反应中心能量分配参数更倾向于光化学反应方向,与生长参数相似,施肥处理对蓝莓叶绿素荧光参数的影响也表现为7.5 g/株的施肥量作用效果最优。施肥处理还改变了蓝莓果实的品质,虽然不同处理下蓝莓果实的维生素C和花色素苷含量以及pH值没有发生明显的改变,但其总糖含量却明显增加,而总酸含量除10 g/株施肥处理外,均呈降低趋势,表现为糖酸比的增加,但与生长和叶绿素荧光参数的变化不同,以5 g/株的施肥量对蓝莓果实品质的提高更有利。因此,施肥虽然可以明显促进蓝莓植株的生长,改善其光合能力和果实品质,但控制施肥量时要综合考虑其生长和品质等因素。     

Maternal nutrition, egg quality and breeding success of Scottish Ptarmigan Lagopus mutus

Samples of Ptarmigan eggs were hatched in captivity. They had been taken from ground adjacent to study areas where the wild birds' breeding success by early August, and their food plants, were measured.
Almost all deaths of chicks in captivity occurred within a few days of hatching and examination postmortem showed no specific cause. The proportion of chicks which died in captivity before 15 days of age varied markedly between years and study areas. These variations occurred in parallel with variations in breeding success in the wild populations from which the eggs had been taken. It was concluded that the survival of chicks both in captivity and in the wild was determined in part before the eggs hatched.
Variations in breeding success from year to year were correlated with the number of days that the food plants had been growing before the hens finished laying. Breeding success in the wild and chick survival in captivity were better for a 'rich' area overlying some base-rich rocks than for a 'poor' one overlying granite and with less blaeberry. It was inferred that, as in Red Grouse, maternal nutrition affected breeding success through the quality of the eggs.     

Effects of hazard-reduction burning on populations of understorey plant species on Hawkesbury sandstone

Density counts were taken for 37 plant species on 12 plots which were assigned to three treatments: spring burn, autumn burn, and control. Post-fire sampling was carried out at intervals of up to 6 years when a second fire treatment was applied, followed by further sampling at 1 year. Most pre-fire species returned by 12 months after fire. Initial recovery was slower on the autumn burn plots and these were surpassed after 12 months by the spring burn plots which remained significantly more diverse until 6 years after fire when the treatments converged. The second fire led to further loss of species, especially on the autumn burn plots. Overall, numbers of individuals were lower in the post-fire community and did not fully recover during the 6 years before the second fire. Of the 37 species followed over the study period, eight had population numbers consistently below pre-fire values, seven showed better recovery on the autumn burn plots, eight showed better recovery on the spring burn plots, and fourteen had population numbers equal to or greater than pre-fire values. Most of the species not fully recovering had relatively poor survival rates. The better recovery rate of species on the autumn burn plots was attributable to better recruitment while the species recovering on the spring burn plots showed better survival and recruitment. The species increasing their numbers after the fire did so through good recruitment or survival, or both. For some species post-fire rainfall or temperature was significantly correlated with greater post-fire recruitment; others were more strongly affected by the treatment itself or more directly by the somewhat different fire intensities in spring and autumn, the differences in soil and litter moisture content, or seasonal variations in soil seed populations.     

Responses by the capercaillie Tetrao urogallus, and the willow grouse Lagopus lagopus, to the green matter available in early spring

Food matter eaten in the first snowless spots early in the spring by capercaillie Tetrao urogallus and willow grouse Lagopus lagopus was studied in Finnish Forest Lapland. When the snow disappears, both species change to feeding mainly on the plants available in the snowless spots, although male capercaillie does not exploit this nutritious diet to the same extent as female capercaillie and willow grouse. Selection in favour of nitrogen and phosphorus-rich food items, i.e. Betula pubescens , male catkins Eriophorum vaginatum , flower buds, and Equisetum spp., stems and tips, seems to be characteristic especially of the female capercaillie, whose winter diet is poor in these elements. Female capercaillie also feeds on more plant species or different parts of plants at one time than willow grouse, while no differences were recorded between male and female willow grouse in the composition of their spring food. The crowberry Empetrum hermaphroditum , almost regularly produces a bountiful berry crop in northern Finland, and since it overwinters well, it represents an easy source of energy and water available almost every spring. The quality and/or the quantity of the green food matter available early in the spring may fluctuate considerably and be of importance for short-term fluctuations in the populations of these tetraonid species.     

Maternal winter body mass and not spring phenology determine annual calf production in an Arctic herbivore

Warming of the Arctic has resulted in earlier snowmelt and green‐up of plants in spring, potentially disrupting the synchrony between plant phenology and breeding phenology in herbivores. A negative relationship between offspring survival in West Greenland caribou and the timing of vegetation emergence was the first finding of such a mismatch in Arctic mammals. However, other studies indicate that the energy for foetal growth and early lactation is predominantly drawn from stored energy reserves typical of ‘capital’ breeders, suggesting that conditions well before spring influence calf production more than the timing of spring onset. Here we use 20 years of observations of marked Svalbard reindeer to evaluate determinants of annual recruitment, as measured by the presence of a calf at foot in mid‐summer. Spring temperatures and the enhanced vegetation index were used as proxies for spring onset, while data on body mass and pregnancy rates in late winter allowed us to determine maternal condition and the reproductive status before spring. Pregnancy rate, offspring survival and annual recruitment were all strongly correlated with average late winter adult female body mass (r = 0.87; r = 0.83; r = 0.92, respectively). Contrary to the findings in West Greenland, neither early calf survival nor annual recruitment were correlated with the two measures of annual variation in spring phenology (r = – 0.07, p = 0.8 and r = – 0.15, p = 0.6, respectively). We also revisit the Greenland data and reveal that the pattern of covariance between early and late measures of fecundity, as well as between early measures of fecundity and offspring survival, correspond with the results from Svalbard. Our results emphasize that conditions affecting maternal body mass during winter explain close to all the variation in recruitment, questioning the importance of the role of a mismatch between plant phenology and calving date.     

Phenology of Dasineura oxycoccana (Diptera: Cecidomyiidae) on cranberry and blueberry indicates potential for gene flow

Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae) is a pest of cranberry, Vaccinium macrocarpon (Aiton) (Ericales: Ericaceae), and highbush blueberry, Vaccinium corymbosum (L.) (Ericales: Ericaceae), in North America. In British Columbia, Canada, D. oxycoccana was first found on highbush blueberry in 1991 and then on cranberry seven years later. Because many cranberry and highbush blueberry farms are adjacent to one another, we hypothesized that D. oxycoccana was moving from highbush blueberry onto cranberry. Cranberry and highbush blueberry differ in phenology, and adaptation to these different phenologies may result in host races or cryptic species on these two crops. We recognized the alternative hypothesis that D. oxycoccana had arrived as immature stages with cranberry vines imported from another region of North America. During spring and summer, we recorded the phenology of D. oxycoccana and the development of plant shoots from three cranberry and three highbush blueberry farms to determine whether the opportunity exists for successful movement of D. oxycoccana between the two crops. Our results show that D. oxycoccana from cranberry and highbush blueberry overlap in phenology for much of the season, indicating a high potential for movement and gene flow. However, differences were seen in number of larvae per shoot, location of pupae, and heat unit accumulation during larval development suggesting that instead there may be the potential for host race or cryptic species formation.     

THE INFLUENCE OF DENSITY OF PLANT POPULATION ON THE INCIDENCE OF YELLOWS IN SUGAR-BEET CROPS

The incidence of yellows virus in sugar-beet crops was reduced by increasing the density of plant population. The variations in plant population were obtained by differences in row width and singling distance. The differences in susceptibility between large- and small-topped varieties, and between early and late sown crops, could not be attributed solely to differences in plant size. It is suggested that close planting would increase the yields of sugar beet and reduce the losses caused by yellows virus. Roguing infected plants during the early part of the growing season did not reduce the incidence of disease.     

Annual changes in the concentration of minerals and organic compounds of Quercus suber leaves

Mature leaves are the primary source of sugars, which give rise to many secondary metabolites required for plant survival under adverse conditions. In order to study the interaction of field‐grown cork oak (Quercus suber L.) with the environment, we investigated the seasonal variation of minerals and organic metabolites in the leaves, using inductively coupled plasma atomic emission spectrometry, elemental analysis and nuclear magnetic resonance spectrometry. Statistical analysis showed that the data strongly correlated with seasonal climate and were divided in three groups corresponding to: (1) spring‐early summer, (2) summer and (3) autumn‐winter. The concentration of N, P, K and leaf ash content were highest in spring (recently formed leaves), reached the minimum during the hot and dry summer and increased slightly during the rainy period of autumn‐winter. Conversely, Na, Mg and Ca concentrations were lowest in spring‐early summer and increased during summer and autumn‐winter, the Ca concentration increasing five‐fold. Two cyclitol derivatives, quinic acid and quercitol were the major organic metabolites of the leaves. Their concentration along the season followed opposite trends. While quinic acid predominated during spring‐early summer, when it contributed 12% to the leaf osmotic potential, quercitol was predominant during autumn‐winter, when its contribution to leaf osmotic potential was about 10%. This different preponderance of the two compounds is expressed by the quercitol/quinic acid ratio, which can be as low as 0.2 in early summer and as high as 9 in winter. Sucrose and glucose concentrations also increased during autumn‐winter. Evidence for the quercitol protective role in plants during stress is discussed, and on the basis of structural similarity, it is suggested that quinic acid could have an identical importance, with a protective role against heat and high irradiance. It is concluded that the marked changes in Q. suber leaf composition throughout the year could have important implications in the plant capacity to endure climatic stress.     

兔眼蓝浆果在南京地区的生长和结实情况

从美国引入的１２个兔眼蓝浆果（ＶａｃｃｉｎｉｕｍａｓｈｅｉＲｅａｄｅ）品种在南京地区的生长和开花结果情况表明,大部分品种与原产地无明显差别。树冠略小于原产地。除个别品种外,单株产量一般高于或与原产地相近。说明兔眼蓝浆果对南京地区自然条件比较适应。但各品种适应程度有差异。适应性最强的品种有Ｂｒｉｇｈｔｗｅｌ、Ｂｌｕｅｂｅｌｅ、Ｃｌｉｍａｘ和Ｇａｒｄｅｎｂｌｕｅ,最差的是Ｄｅｌｉｔｅ,其他品种一般。花期早晚与倒春寒危害有关,值得注意。     

Density dependent processes and the importance of periodic germination in the winter annual plant Saxifraga osloensis

Saxifraga osloensis is an allopolyploid plant, endemic to Scandinavia A field study of Its population biology was performed during two years, 1989-90 and 1990-91 The timing of different life stages in spring was correlated with weather conditions, mainly temperature Density effects were found on survival of rosettes in autumn and on capsule production in spring It seemed as if the density effects occurred only when the initial density was very high or when there was shortage of water Most plants emerged in autumn, but between 10% and 15% emerged m spring Spring gemunators were exposed to higher mortality risks in spring than autumn germinators Fitness, estimated as life-time capsule production, was lower for spring cohorts both years Most plants in the spring cohorts produced no seeds Thus, spring germination should not be selected for in this population     

Seasonal variations of metal concentrations in periphyton and taxonomic composition of the algal community at a Yenisei River littoral site

The concentrations of metals K, Na, Ca, Mg, Fe, Mn, Zn, Cu, Ni, Pb, Co and Cr, in the water and periphyton (epilithic algal communities) were studied at a site in the middle stream of the Yenisei River (Siberia, Russia) during three years using monthly sampling frequencies. Despite considerable seasonal variations in aquatic concentrations of some metals, there was no correlation between metal contents in the water and in periphyton. Seasonal concentration variations of some metals in periphyton were related to the species (taxonomic) composition of periphytic microalgae and cyanobacteria. Enhanced levels of Ni and Co in periphyton in late autumn, winter, and early spring were likely caused by the predominance of cyanobacteria in the periphytic community, and annual maximum levels of K in periphyton in late spring and early summer were attributed to the domination of Chlorophyta, primarily Ulothrix zonata.     

The utilization of heather moorland by territorial Red Grouse Lagopus lagopus scoticus

Although the breeding density of Red Grouse Lagopus lagopus scoticus is related to the density of burned patches of heather Calluna vulgaris , territories appear to offer surplus food, and other factors, especially the risk of predation, may be important. In order to determine how Red Grouse make use of heather moorland, an individually marked population was studied on a moor in northeast Scotland from 1992 to 1994. Territorial birds preferred stands of tall heather during the daytime in autumn and winter, but in spring they increased their use of heterogeneous heather/grass mixtures. Furthermore, in spring, females showed a very strong affinity for edges between heather stands of different ages, where they had easy access to nutritious young heather and good cover. When near the vegetation edge, territorial birds spent most time on the side of the edge providing greater cover. Broods occupied ranges in areas with rather more old heather and with more edge than was available over the entire study site. Within their ranges though, broods clearly preferred heterogeneous areas during the first month after hatching, and showed a further preference for vegetation edge. Their behaviour changed during the second month after hatching, when they utilized tall heather to a greater extent, but edge remained important.     

SEASONAL PATTERN OF NET PHOTOSYNTHESIS OF ARTEMISIA TRIDENTATA

Gas exchange studies were carried out on Artemisia tridentata during the course of a growing season using microclimatically controlled cuvettes and infrared gas analysis. A definite seasonal pattern of net photosynthesis emerged. This pattern was influenced by the interaction of four major factors: plant water potential, leaf temperature, irradiation, and stage of phenological development. In spring and early summer, when plant water stress was minimal, photosynthesis rate was mainly correlated with leaf temperature and irradiation. During mid and late summer, increased plant water stress and phenological changes assumed at least equal importance with temperature and irradiation in limiting net photosynthesis. Indeed, plant water potential, mainly through its influence on stomatal aperture, r_s‘, was probably the single most important factor influencing assimilation rate of this species on a seasonal basis. However, variations in mesophyll resistance to CO₂ flux, r_m‘, in response to temperature, water stress, or phenological changes also were involved. Sagebrush photosynthesis under field conditions was highest in late May and early June, and declined thereafter, minimum rates occurring in August during the driest period. Optimal temperatures for net photosynthesis were higher later in the season, indicating a change in gas exchange capacity more suitable to the warmer temperatures later in the season.     

Climatic effects on the breeding phenology and reproductive success of an arctic-nesting goose species

Climate warming is pronounced in the Arctic and migratory birds are expected to be among the most affected species. We examined the effects of local and regional climatic variations on the breeding phenology and reproductive success of greater snow geese ( Chen caerulescens atlantica ), a migratory species nesting in the Canadian Arctic. We used a long-term dataset based on the monitoring of 5447 nests and the measurements of 19 234 goslings over 16 years (1989–2004) on Bylot Island. About 50% of variation in the reproductive phenology of individuals was explained by spring climatic factors. High mean temperatures and, to a lesser extent, low snow cover in spring were associated with an increase in nest density and early egg-laying and hatching dates. High temperature in spring and high early summer rainfall were positively related to nesting success. These effects may result from a reduction in egg predation rate when the density of nesting geese is high and when increased water availability allows females to stay close to their nest during incubation recesses. Summer brood loss and production of young at the end of the summer increased when values of the summer Arctic Oscillation (AO) index were either very positive (low temperatures) or very negative (high temperatures), indicating that these components of the breeding success were most influenced by the regional summer climate. Gosling mass and size near fledging were reduced in years with high spring temperatures. This effect is likely due to a reduced availability of high quality food in years with early spring, either due to food depletion resulting from high brood density or a mismatch between hatching date of goslings and the timing of the peak of plant quality. Our analysis suggests that climate warming should advance the reproductive phenology of geese, but that high spring temperatures and extreme values of the summer AO index may decrease their reproductive success up to fledging.     

Parental Nutrition and Chick Production in Captive Willow Ptarmigan (Lagopus L. Lagopus)

The breeding performance of captive willow ptarmigan on different diets has been studied. The nutritional factors tested were protein concentration, natural feed supplement and grass meal and flavonoid admixture, and effects on egg numbers, fertility, hatchability, chick weights at hatching and 0–14 days mortality have been recorded. The breeding performance of ptarmigan hen in captivity showed great individual variations. Egg numbers were not statistically different in groups fed the different diets. Hens fed a 15 % crude protein died tended to produce smaller chicks with significantly lower viability than chicks from hens fed a 20 % crude protein diet. Supplement of natural feed tended to increase the number of chicks hatched through a combination of tendency to higher egg numbers and improved fertility. These tendencies were, however, statistically nonsignificant. Inclusion of 34 % grass meal to the diet also tended (non-significantly) to improve fertility and hatchability, while inclusion of flavonoids had no positive effect on reproduction. Eggs from captive hens showed significantly lower fertility, and a tendency to lower hatchability than eggs from wild hens. The former difference was probably caused by the close cage confinements for the captive ptarmigan, while the latter condition probably was due to different start of incubation, most of the eggs from wild hens being started naturally.