Host-preference and density of woodrose-forming mistletoes (Loranthaceae) on savanna vegetation,South Africa

In the Bushbuckridge region of South Africa host preference and density of two woodrose-forming mistletoes, Erianthemum dregei (Eckl. & Zeyh.) V. Tieghem and Pedistylis galpinii (Schinz ex Sprague) was quantified in relation to land-use (harvested or unharvested), rainfall (high > 660 or low < 660 mm year^–1) and catenal position (top or lower slope). These two mistletoes are generalist hemi-parasites of savanna trees and shrubs occurring on 25 and 17 hosts respectively, seven of which are shared. Thirty-six percent of woody plant species recorded were found to be hosts. Although Sclerocarya birrea (A. Rich.) Hochst. comprised only 4% of woody plant density in the environment, it was the principal host for both mistletoes, accounting for 71% of total E. dregei and 42% of P. galpinii infection. Mistletoe infection relative to density of Ficus stuhlmanii, Trichilia emetica and Cassine transvaalensis indicated that these were preferential hosts to S. birrea. Mistletoe host preference was negatively correlated with host wood density. Mistletoe number per tree had a weak relationship to canopy size. Mistletoes of all size classes were denser at high rainfall relative to low rainfall sites. Interestingly, the overall mistletoe size class distribution was similar between harvested and unharvested sites. The ratio of living to dead mistletoe was 2 to 1 for E. dregei and 1.5 to 1 for P. galpinii. There are sufficient dead mistletoes in unharvested and harvested areas to satisfy present market demand. Living E. dregei predominated in harvested rather than unharvested areas suggesting that current-harvesting levels had little or no negative effect on the population. In contrast, P. galpinii was denser in unharvested areas possibly owing to its higher market value and thus higher harvesting levels.     

A potential threat to tomato,a congener crop to potato from invaded potato tuber moth,Phthorimaea operculella (Zeller)

Potato tuber moth (PTM) is a primary pest of potato which had invaded into Korea in 1968 and its distribution was restricted in the southern part of the peninsula. Possibly due to the climate change, its distribution expanded toward the Northern part of South Korea including Gyounggi and Gangwon province where tomato production is high. Host expansion and damage potential of PTM was evaluated on tomato, a congeneric crop of potato. Three commercial varieties of tomato (Dafnis, Bangul and Jujube) and a potato (Superior-Sumi) were subjected to PTM larvae. The results showed that host suitability of tomato to PTM was lower than potato, but PTM could completely develop and reproduce on tomato leaves or fruits. Development time was varied relative to tomato varieties and plant age. PTM showed lower performance on the leaves and fruits of cherry type tomatoes. Higher survival was observed in the large sized fruit of tomato varieties. This study showed substantial evidence that the invaded PTM could damage the tomato cultivation.     

Preferential β-sheet structuration of multiconformational poly(Glu-Leu) by metallic ions

Summary Alternating poly(Glu-Leu) exhibits a random coil structure in pure water at neutral pH. The addition of 0.5 equiv of Ca²⁺ induces a coil-to-β-sheet transition and the addition of 0.15 equiv of Fe³⁺ induces a coil-to-α-helix transition. Conformational competition between these two structures was studied by mixing preformed β-sheets and α-helices in different proportions. Circular dichroism spectra clearly show that β-sheets are favored at the expense of α-helices in β-sheet-rich mixtures.     

Comparing the role of the height of men and women in the marriage market

This paper explores how the role of men and women’s height in the marriage market has changed across generations. Using individual-level data from Japan, we compared the effect of height on marriages between men and women, and investigated how the effect of height on marriage has changed across generations. Our key findings are: (1) for men born before 1965, a 1% increase in height led to an approximately 0.56% increase in the probability of being married. Conversely, for women born before 1965, a 1% increase in height led to an approximately 0.56% decrease in the probability of being married. (2) For men born in or after 1965, a 1% increase in height led to an approximately 1.05% (0.18%) increase (decrease) in the probability of being married (divorced). However, the height effect was not present for women. Japan experienced astounding economic development after World War II, which resulted in changes in its economic and social structure. These changes may have also altered the role of height for Japanese men and women in the marriage market.     

Strategies for control of eyespot (Pseudocercosporella herpotrichoides) in UK winter wheat and winter barley

This review considers strategies for control of eyespot (Pseudocercosporella herpotrichoides) in winter wheat and winter barley in the UK. Varietal resistance to eyespot may take the form of direct resistance to the growth of the pathogen in the stem base or of indirect tolerance to eyespot through resistance to lodging. The French variety Cappelle-Desprez has been a source of resistance for most UK wheat varieties and a new source of resistance in wild goat grass has been discovered recently. Use of fungicides for control of eyespot increased rapidly after the introduction of the highly effective MBC fungicides in the 1970s, but has decreased recently because UK populations of P. herpotrichoides are now predominantly resistant to MBC fungicides and alternative fungicides are more expensive. Historically, cultural methods, especially crop rotation, have been important in the control of eyespot. The importance of cultural control of eyespot is now increasing because more non-cereal break crops are being grown and fungicide use is declining.     

Assessment of landscape aesthetics—Validation of a landscape metrics-based assessment by visual estimation of the scenic beauty

The assessment of cultural ecosystem services, in our case landscape aesthetics, is the most commonly investigated but least formalized issue in the scope of the ecosystem services concept. In contrast to ecological or economic aspects, the assessment of aesthetics cannot easily be based on quantitative information. Therefore, two different methodological approaches that assess landscape aesthetics either from an objective or a subjective point of view have been established in the past.This article presents in its first part an objective, landscape metrics-based assessment approach. We defined naturalness and landscape diversity as assessment criteria and selected Shannon's Diversity Index (SHDI), Shape Index (SHAPE) and Patch Density (PD) as indicators. We tested our approach for a set of nine different landscape types in a model region in Saxony, Germany.For validating the developed methodology, we carried out a survey with 153 participants in order to investigate their subjective preferences for the different landscape types. These preferences had to be expressed by rating the landscape types on a scale from 1 (very ugly) to 5 (very beautiful). The study was based on three different data sets, namely photographs of the landscape types, satellite images, and land cover maps.Statistical tests were applied (a) to investigate the impact of personal factors on the ratings, (b) to detect whether abstraction levels are suitable for preference studies, and (c) to compare the results of the objective approach (landscape metrics) and the subjective approach (visual assessment). Personal factors did not influence the visual assessment results significantly. We found the highest correlation of the landscape metrics-based assessment with the visual assessment results of the photographs. We conclude that the three landscape metrics might be applied to the monitoring of landscape aesthetics. An extended study with more participants might be useful to further investigate the reliability of our findings.     

Do birch-feeding caterpillars make the right feeding choices?

Summary The effects of leaf quality on caterpillar performance are frequently investigated, as are the feeding preferences of caterpillars, but rarely are the two considered together to see how preferences match performance. I looked at the preferences and performance of the specialist feeder Achlya flavicornis and the generalist Spilosoma luteum on Betula pendula leaves which were artificially damaged, mined or left undamaged, and on leaves of different ages. Often feeding preferences were not for the leaf types that gave faster development, larger pupae or greater survival. A. flavicornis preferred medium aged to older leaves though medium aged leaves produced smaller pupae. They did not discriminate between young and medium aged leaves, though larvae fed young leaves developed more slowly, and had lower survival and lower adult emergence. S. luteum larvae did not discriminate between damaged and undamaged leaves, though feeding on damaged leaves gave smaller pupae and lower adult emergence. I suggest that generalists like S. luteum might be unable to make feeding choices between leaves that are on the same tree and vary only slightly because populations are exposed to much greater variation across the wide range of potential food plants individuals may encounter. Possible differences in within-plant feeding selectivity between generalists and specialists should be investigated. A. flavicornis is a leaftier for which selection of a suitable leaf for tying could be more important in the first instance than feeding considerations. Larvae preferred younger to older leaves for tying, and larvae tended to feed on the tied leaves, so tying preferences explain the initial feeding preferences.     

Nutritive value of maize stover/pasture legume mixtures as dry season supplementation for sheep

Two experiments were carried out to determine the nutrient contents and relative preferences of maize stover and three legumes forages and their feeding on intake and digestibility of sheep. Maize stover was blended with three legumes, stylo (Stylosanthes guainensis), siratro (Macroptilium atropurpureum) and centro (Centrocema pubescens), to produce four treatments, namely, only maize stover (control), stover/stylo, stover/siratro and stover/centro mixtures. The first experiment evaluated the relative preference of the stover and the various stover/legume mixtures when offered to sheep. Six rams were offered pair combinations of the treatments in a 6×6 Latin square with a split plot arrangement such that each ram had access to two feeds at a time in each period of 6 days. The second experiment included measurements of intake and digestibility of the stover and stover/legume mixtures. Four intact and four castrated male sheep were used in two, 4×4 Latin squares with 21-day periods. The least (P<0.05) preferred feed was maize stover when it was offered as the sole feed. There were no significant differences in preference among the stover/legume mixtures. Dry matter intake (DMI) was highest (P<0.05) when sheep were offered the stover/centro mixture and lowest (P<0.05) when maize stover was fed as the sole feed. Dry matter digestibility did not differ significantly among treatments. Sheep that were offered maize stover only lost weight, those fed stover/centro gained weight and those that were fed either stover/siratro or stover/stylo maintained weight. However, these short-term weight changes may reflect changes in fill as much as changes in body tissue. Addition of legumes to maize stover improved the nutritive value, possibly by increasing the nitrogen content of the stover. The results suggest that maize stover, which is normally left to rot in the field, could be better utilised by intercropping with legumes and allowing animals access after grain harvest.