Selection of foraging habitat and nestling diet by Meadow Pipits Anthus pratensis breeding on intensively grazed moorland

Capsule Foraging sites with low vegetation height and density, but with high arthropod biomass, are selected.

Aims To test the hypothesis that on intensively grazed moorland, breeding Meadow Pipits forage for nestling food where arthropod prey are most readily available, and therefore that foraging site choice is a function of prey abundance and vegetation structure.

Methods Observations of adults provisioning nestlings were made from hides positioned close to 19 nests within grazed, 3.3-hectare experimental plots at Glen Finglas, Scotland. Vegetation height and density and arthropod abundance from mapped foraging sites were compared with control sites. Prey items fed to nestlings were quantified and compared with their relative abundance.

Results Meadow Pipits selected foraging sites with significantly lower vegetation height and density, but with significantly higher arthropod biomass. Our data suggest that within foraging sites, Meadow Pipits select particular prey types to provision nestlings, in particular, Lepidoptera larvae, adult Tipulidae and Arachnida.

Conclusions In intensively grazed upland systems, it appears that Meadow Pipits select foraging sites that optimize total food abundance and accessibility. In order to understand how anticipated changes to livestock farming in Europe will affect grassland birds, we recommend that future studies should investigate the foraging and vigilance behaviour, diet composition and breeding success of a variety of bird species provisioning nestlings under a range of livestock management scenarios.     

Insect and small mammal herbivores limit tree establishment in northern Mongolian steppe

The extent to which human activities expanded the range of central and north-eastern Asian steppes into the forest is controversial. Natural versus anthropogenic causes of the inhibition of tree growth were investigated in a case study in the western Khentey Mountains in montane meadow steppe on sun-exposed southern slopes, representing treeless outposts within the northern Mongolian mountain taiga. Sowing and planting experiments with Mongolia’s most common tree species, Larix sibirica, did not result in the successful establishment of any tree during one growing season, despite the exclusion of grazing by large herbivores from the sample plots by fencing. Less than 1% of the seeds germinated 4 weeks after sowing in spring. All seedlings died within a further 3 weeks due to drought and heat. Two-year-old seedlings suffered from drought as well as from feeding by of gypsy moth larvae (Lymantria dispar), grasshoppers and rodents. While the gypsy moth was effective at damaging L. sibirica only during few weeks at the beginning of the growing season, feeding by grasshoppers and rodents persisted through the entire growing season. At the end of the growing season two thirds of the seedlings died due to insect and small mammal herbivory and one third due to drought-related damage. Herbivores attacked larch seedlings more rapidly on the open meadow steppe than at the forest edge. Drought and high temperature at the soil–air interface are crucial for inhibiting tree encroachment on the studied steppe slopes. Competition by non-arboreal plants is of subordinate significance for the establishment of L. sibirica. Trees can only establish at especially favorable microsites under humid weather conditions. Such trees, however, are exposed to a high risk of mortality from insect or small mammal herbivory.     

温度对草地螟成虫产卵和寿命的影响

在16℃、19℃、22℃、25℃.28℃,31℃和34℃的范围内, 草地螟(Loxostege sticticalis L.)成虫的产卵前期与温度的关系呈逻辑靳谛曲线,产卵雌蛾数、产卵历期和产卵量均以22℃为最高。初步确定19-25℃为草地螟蛾产卵的适温范围,22℃为最适产卵温度,16℃和34℃分别为产卵温度的下限和上限。成虫寿命与温度的关系为负相关(r=-0.91,P<0.01)。表明在试验温度范围内,温度越高,成虫寿命越短。但温度对雌雄成虫寿命的影响不一致,在28℃以下的温度内,雄蛾寿命比雌蛾长;在31-34℃的范围内,雄蛾寿命比雌蛾短。根据以上研究结果,对我国草地螟发生为害区的种群动态规律进行了讨论。     

小菜蛾幼虫空间分布型和抽样技术的研究

小菜蛾幼虫空间分布型测定结果表明：（1）频次分布检验为负二项分布;（2）素集度指标测定为聚集分布;（3）m^*-m的线性回归方程为m^*=0.0114 1.4608m,表明了属于最普通的聚集分布（负二项分布）。根据素集均数λ测定值结果,分析了聚集原因,在分布型研究的基础上探讨了Kuno种群序贯抽群的模型。     

The effects of a multispecies sequential diet on the growth and survival of a tropical polyphagous caterpillar

Hylesia lineata Druce (Lepidoptera: Saturniidae) caterpillars are highly polyphagous at the individual level. I examined the effects of a multispecies sequential diet on the performance of the larvae. The experiment included three natural hosts respectively —Casearia corymbosa HBK,Thouinia paucidentata Radlk., andErythroxylum havanense Jacq — used by ovipositing females in proportion as expected by their abundance;C. corymbosa andE. havanense representing the most and least abundant hosts respectively. All possible two-host and single-host diets were tested. Larval survival to the pupal stage (as protected by a field cage) did not differ among all diets. Also, for females, regardless of the identity of the initial host, the final weight and the developmental time depended entirely on the nature of the final host. Male performance, in contrast, only differed in terms of developmental time but again the initial host did not affect the final result. It was concluded that a host switch early in the development of the caterpillars does not affect further growth on the other host plants. Caterpillars that finished their development onE. havanense reached small sizes but females devoted a larger proportion of their resources to egg biomass; as a result female fertility was similar among females regardless of their feeding history. I concluded that the caterpillar's abilities and the female compensatory flexibility may oppose selection for a strong preference hierarchy in the female ovipositing behavior.     

Thermal properties of the tent of early instar colonies of the eastern tent caterpillar, Malacosoma americanum (Lepidoptera: Lasiocampidae)

The extent to which the small tents of the early instars of Malacosoma americanum warmed when irradiated by sunlight was investigated by continuous electronic monitoring of field colonies for 137 colony-days. Tent temperatures exceeded the threshold for larval growth of 15 °C on 88–96% of the study days, exceeding in degree-minutes the ambient excess-over-threshold by a factor of approximately five. In still air, tents constructed by third instar caterpillars achieved greater temperature excesses over ambient than did a model of a tightly sealed glass house, but smaller tents and tents exposed to simulated wind did not perform as well. Tents of M. americanum warmed more rapidly and to a high temperature than silk nests of markedly different design constructed by other species.     

三种松毛虫不同地理种群遗传多样性

运用13个ISSR引物对赤松毛虫(Dendrolimus spectabilis)、油松毛虫(Dendrolimus tabulaeformis)、落叶松毛虫(Dendrolimus superans)的种群遗传分化进行分析.13 个引物共产生195条带,其中184条具多态性,总的多态位点百分率为94.36%,扩增谱带具有明显的种间多态性.Shannon 信息指数和Nei信息指数均表明落叶松毛虫群体内的遗传多样性最高,油松毛虫与赤松毛虫则相差不多.各种松毛虫的不同地理居群出现了遗传分化,由Nei指数估计的群体间的遗传分化系数分别为15.50%、32.57%和41.92%.用UPGMA法对Nei′s遗传距离作聚类分析.聚类结果表明:不同地域的油松毛虫遗传距离与地理距离呈一定程度的相关趋势.     

Primary and secondary induction requirements for flowering in Alopecurus pratensis

The critical temperature for primary induction of flowering in two Norwegian eco-types of meadow foxtail ( Alopecurus pratensis L.) was about 21°C, with 6 weeks induction period. Inflorescence primordia were initiated with increasing effectiveness as the temperature was reduced below this level in both short days (SD) and long days (LD), although SD was the more effective photoperiod at all temperatures above 6°C. The degree of primary induction was closely negatively correlated with the length of basal leaves. Culm elongation and heading (secondary induction) were promoted by LD and high temperature and inhibited by the combination of SD and low temperature. The relationship between SD primary induction and vernalization is discussed in the light of these and other results.     

Factors influencing nocturnal egg-turning frequency in Meadow Pipits Anthus pratensis

Capsule Mean frequency of nocturnal egg-turning in Meadow Pipits is similar to that found in other passerines. Turning frequency changes during incubation, with time since the start of incubation exerting the strongest influence.     

Comparative studies on the nuclear polyhedrosis viruses of Lymantria monacha and L. dispar

Immunodiffusion and tube precipitation tests, polyacrylamide gel electrophoresis of virus polypeptides, and cross-transmission experiments suggest that two nuclear polyhedrosis viruses, one from Lymantria monacha and one from L. dispar, are partially related to each other, but not identical. The virus particle proteins seem to be more specific than the polyhedron proteins.     

Modelling the effects of inherited sterility for the application of the sterile insect technique

1 The sterile insect technique (SIT) involves the release of large numbers of sterile or partially‐sterile insects into a wild pest population to dilute the number of successful wild matings, with the eventual aim of eradication or area‐wide suppression. General population models, encompassing a wide range of SIT types, were used to derive principles for optimizing the success of SIT, with particular emphasis on the application of partial sterility leading to inherited sterility in the F₁ population. 2 The models show that inherited sterility can only be guaranteed to be more effective than complete sterility if matings between irradiated‐lineage partners are unsuccessful. This is widely assumed but rarely examined experimentally. 3 The models allow the critical overflooding ratio, φ_c, to be calculated for a particular target species, suggesting the release rate required to prevent population increase. Successful eradication using SIT alone should aim for a substantially higher release rate than suggested by φ_c. 4 The models show that pest populations may continue to increase in the first few generations of SIT releases, regardless of release rate, as irradiated‐lineage individuals infiltrate the population. This does not necessarily imply that the SIT programme will be unsuccessful in the longer term. 5For pests with overlapping generations, the models suggest that frequent small releases may be more effective than less frequent large releases, particularly when the average release rate is close to the critical threshold for success.     

Predators ofLymantria dispar (Lep. lymantriidae) egg masses: Spatio-temporal variation of their impact during the 1988–89 pest generation in the mamora cork oak forest (Morocco)

In the Mamora cork oak forest (Morocco), oophagous predators of the gypsy mothLymantria dispar (L.) (Lepidoptera: Lymantriidae) are one of the main mortality factors influencing pest population dynamics. The predators destroy egg masses more by disrupting their cohesiveness than by predation. From 1987 to 1990, the impact of oophagous enemies significantly contributed to the collapse of a localized gypsy moth outbreak. Variation of egg mass dislocation intensity was greater between trees than among the different strata of a tree. The number of gypsy moth egg masses and egg predator attacks increased when oaks were large and unhealthy. Forest degradation probably explains why egg mass destruction rates were so high (60 to 90% of the eggs) in the infested forest. Oophagous predators find food and shelter under the dehiscent bark of unhealthy cork oaks.     

苹果蠹蛾在中国的扩散与危害

【背景】苹果蠹蛾原产于欧亚大陆,是世界著名的严重危害苹果生产的入侵害虫,也是中国的重要对外检疫性有害生物。【方法】通过收集整理历史文献、资料,并于2005~2013年使用标准性信息素诱芯对全国各苹果、梨主产区的苹果蠹蛾发生情况进行系统监测,明确该虫在我国的分布现状及扩散历史;此外,使用特定公式对苹果蠹蛾在发生区造成的当前经济损失和扩散完成后的潜在经济损失进行了系统评估,以明确该虫在我国的现有和潜在危害。【结果】苹果蠹蛾于1953年首次在中国新疆被发现,目前在中国分布于新疆、甘肃、内蒙古、宁夏、黑龙江、辽宁和吉林7省的144个县(市、区、旗),主要集中分布在东经74.56°~106.8°以及东经120.02°~132.95°,发生面积约49410 hm~2;经济损失评估结果显示,苹果蠹蛾导致中国苹果和梨的潜在减产数量为185.01万和81.33万t。【结论与意义】该虫已在中国形成东西2个分布区,对占据中国苹果产量80%的西北黄土高原(陕西为主)和渤海湾(山东、河北、辽宁为主)两大苹果主产区构成了严重威胁,须引起高度重视。