Temporal pattern of resource use and variation in diets of individual grasshoppers (Orthoptera: Acrididae)

Patterns of resource fidelity, switching, and variation in individual diet were examined in the polyphagous grasshopper Taeniopoda equesforaging in experimental cages over an 11-day period. Ten novel dicots were provided in the cages, but grasshoppers fed primarily on kale (Brassica oleraceavar. acephala),lobelia (Lobelia erinus),pansy (Viola x wittrockiana),and dry bermuda grass (Cynodon dactylon).Grasshoppers showed significant fidelity to a single plant within a meal but tended to eat less of the same plant in the next meal and, in the case of pansy, on the next day. Grasshoppers switched nonrandomly, suggesting that compensatory feeding on complementary resources may have occurred. There was no evidence that behavioral interactions among individuals increased switching rate or lowered fidelity. Overall patterns of resource use varied significantly among grasshoppers during the study, despite frequent switching among resources and a significant tendency to aggregate while feeding. All individuals were polyphagous but differed in relative consumption of available plants. The results suggest that individual grasshoppers express different feeding patterns that are consistent over time and that variation in diet among individual observed in the field may be more than simple sampling error.     

Piping plover chick ecology following landscape-level disturbance

Population declines of disturbance-dependent species due to suppression of natural disturbances are realized across ecosystems. The piping plover (Charadrius melodus; plover), a disturbance-dependent and conservation-reliant shorebird that nests on sandy beaches and barrier islands on the Atlantic Coast, was listed under the United States Endangered Species Act in 1986. In 2012, Hurricane Sandy landed on Fire and Westhampton islands, barrier island nesting sites for plovers in New York, USA. Hurricane Sandy was a natural disturbance in this system, creating abundant nesting habitat. The number of chicks produced by a pair, or a population, is a direct measure of reproductive output, and gaining a better understanding of productivity and chick behavior following large-scale habitat creation may improve plover habitat management and potentially species persistence. We evaluated the effects of landscape features on habitat selection, behavior, and survival of plover broods using logistic regression, generalized linear mixed effects models, and survival models. Plover broods selected flatter sites with less dense vegetation than available at random. Chick foraging rates were highest in moist substrates and were lower in areas of higher nesting plover density. Chick survival was greater for broods that hatched earlier in the breeding season and increased as chicks aged. Generally, providing access to sites with flatter, moist substrates will likely result in higher quality brood rearing habitat on the landscape. Ultimately, vegetation removal and habitat management may be needed to reduce plover nesting density and ensure sufficient habitat, which may in turn improve plover chick survival. Moreover, sustaining natural landscape disturbances such as those resulting from storms, and not taking actions to prevent hurricane-created overwash, will allow these landscape features to persist.     

湖北竹溪植被的基本特征

竹溪县现有种子植物１２７科４８３属８６３种。地理成分复杂,联系广泛,以温带成分占主导地位,占非世界分布属的６４．８３％,热带分布属则占２９．３９％,木本植物占种子植物总数的４２．５９％,主要植补类型计７个植补型组,１０个植被型,４９个联系。地处竹溪中南部的云雾溪是目前亚热带区域保存较为完整,具有多方面保护价值的综合区,建议辟为自然保护区。     

3. Genetic conservation in seed banks

The safest and most economical and convenient way of preserving the genetic resources of the majority of crop plants is by long-term seed storage. The technology is well developed, but recent research resulting from a greater understanding of behaviour at very low water potentials is leading to further improvements     

The applicability of the plant vigor and resource regulation hypotheses in explaining Epiblema gall moth–Parthenium weed interactions

A basic question in insect–plant interactions is whether the insects respond to, or regulate plant traits, or a complex mixture of the two. The relative importance of the directions of the influence in insect–plant interactions has therefore been articulated through both the plant vigor hypothesis (PVH) and the resource regulation hypothesis (RRH). This study tested the applicability of these hypotheses in explaining the interactions between Parthenium hysterophorus L. (Asteraceae) and its stem‐galling moth, Epiblema strenuana Walker (Lepidoptera: Tortricidae). Parthenium plants exposed to galling were sampled at three sites in north Queensland, Australia, over a 2‐year period, and the relationship between gall abundance and plant vigor (plant height, biomass, flowers per plant, and branches per plant) was studied. To test the predictions of PVH and RRH, the vigor of parthenium plants protected from galling using insecticides was compared to galled plants and plants that escaped from galling. The vigor of ungalled plants was less than the vigor of galled plants. The higher plant vigor in galled plants was not due to galling, as was evident from insecticide exclusion trials. The insect seemed to preferentially gall the more vigorous plants. These findings support the predictions of the PVH and are contrary to those of RRH. Since gall abundance is linked to plant vigor, galling may have only a limited impact on the vigor of parthenium. This has implications for weed biological control. If the objective of biological control is to regulate the population of a plant by a galling insect, a preference for more vigorous plants by the insect is likely to limit its ability to regulate plant populations. This may explain the paucity of successes against biocontrol of annual weeds using gall insects.     

Sequential style removal in highbush blueberry,Vaccinium corymbosum L.: Effects on fertilization success and seed germination

Plants of the blueberry cultivar Bluecrop were pollinated with pollen from the cultivars Sierra and Duke under controlled conditions. After pollination, styles were removed at 6 h intervals from 1.25 days to 4.00 days. An increase in the number of developed seed was seen across time, ranging from 1 seed per fruit (s/f) at 1.25 days, to a peak of 63.4 s/f at 3.25 days in 1992, and from 0.1 s/f at 1.25 days to 56.0 s/f at 3.75 days in 1993. Germination tests of 200-seed seedlots of Bluecrop×Sierra exhibited a significant trend toward earlier germination by seed from earlier style removal times. Seed weight measured in the cross Bluecrop×Duke, however, showed decreasing weights with longer style removal times, suggesting that seed size may time of germination. A multiple regression of seed size and stylar removal time against time of germination showed that style removal time was the only significant source of variation for germination time. Results suggest that pollen vigor, as reflected in the speed of growth down the style, may have a direct bearing on characteristics of the seed and subsequent plant.     

Comparison of two cacao (Theobroma cacao L.) clones for the effect of pollination intensity on fruit set and seed content

We compared the influence of pollination intensity (PI) on fruit set and seed number per pod in two cacao (Theobroma cacao L.) clones, IFC5 (Forastero Lower-Amazon Amelonado), which is self-compatible and known to produce a high number of seeds per pod under open pollination, and SCA6 (Forastero Upper-Amazon), which is self-incompatible and known to produce a low number of seeds per pod under open pollination. With both clones, PI had a positive effect on fruit set, with the maximum rate requiring more than 150 pollen grains per pod. One-half of the maximum rate of fruit set was reached with 39 pollen grains per pod for SCA6, and 78 for IFC5. With SCA6, a significant positive effect of PI on seed number per pod was also observed, with maximum seed number requiring more than 200 pollen grains per pod. In contrast, seed numbers with IFC5 were approximately equal over the PI range 100–800 pollen grains per pod. Patterns of seed number per pod were compared after: (1) open insect pollination, (2) low-intensity hand pollination and (3) high-intensity hand pollination. The patterns obtained with IFC5 under open pollination showed a peak of 40–50 seeds per pod, whereas the distribution patterns were more even with SCA6. The pattern of seed number under open pollination was similar to that obtained with high-intensity hand pollination for IFC5, and with low-intensity hand pollination for SCA6. We concluded that the high number of seeds per pod observed with IFC5 under natural insect pollination may be explained by a high number of compatible self-pollen grains on the stigma and by a severe drop of low-pollinated flowers eliminating potential lowfilled fruits. With SCA6, however, the number of compatible pollen grains deposited on the stigma was probably low under open pollination, and the flowers required lower pollen quantities to set fruit, which resulted in a high frequency of low seed numbers per fruit. This difference in the capacity to set low-seeded fruits might be considered as an adaptive trait related to the mode of reproduction.     

庐山野生观赏植物资源多样性及持续利用对策

庐山是我国著名的风景旅游和避暑胜地,也是我国中亚热带北缘植物多样性的宝库．本文在广泛调查、收集、整理的基础上,研究了庐山野生观赏植物资源多样性特征、分布、类型及其配置．本区分布有野生观赏植物５２８种,隶属于１１５科２９０属,其中乔木类１３８种,灌木类１４０种,藤木类５２种,草本类１９８种．并根据开发与保护现状对庐山野生观赏植物资源多样性的持续利用提出了切实可行的对策．     

宜昌大老岭种子植物区系研究

大老岭有野生种子植物１２２科４３５属８５６种。对本区科、属和种进行了统计与分析,结果表明,该地区的植物区系性质明显是温带性,且以北温带成分为主,地理成分复杂,仅属就有１３个分布区类型和１７个变型,地理联系广泛,具有古老性强和特有现象不很突出的特点。