Seasonal activity,habitat preferences and larval mortality of the leaf-mining fly Calycomyza eupatorivora (Agromyzidae), a biological control agent established on Chromolaena odorata (Asteraceae) in South Africa

The leaf-mining fly Calycomyza eupatorivora Spencer (Diptera: Agromyzidae) has become widely established in the eastern regions of South Africa, following its release for the biological control of the invasive shrub Chromolaena odorata (L.) King and Robinson. This study was conducted to gain some insight into the impact of C. eupatorivora populations, by assessing their seasonal activity, habitat preferences, levels of leaf exploitation and extent of larval mortality in the field over a 1-year period. Leaf mining intensity was poorly synchronised with leaf availability, with leaf exploitation peaking at the end of the growing season of C. odorata. Although significantly more mines were recovered on plants growing in shaded situations, the percentage of available leaves that were exploited for mining was not significantly different between plants growing in shaded versus open situations. Overall, the levels of leaf damage were trivial with mines recovered from <5% of available leaves that were sampled during the study. Besides leaf-quality requirements, these low levels of leaf exploitation may have been influenced by high larval mortality which varied between 60 and 83%, depending on whether lower or higher estimates were used. These evaluations have verified the results of earlier laboratory studies which suggested that the impact of C. eupatorivora on mature populations of C. odorata in South Africa will be negligible.     

Industrial pollution affects behaviour of the leafmining moth Stigmella lapponica

We explored the impacts of industrial air pollution on the behaviour of the leafmining moth Stigmella lapponica (Wocke) (Lepidoptera: Nepticulidae) by comparing the characteristics of larval gallery mines in mountain birch [Betula pubescens ssp. czerepanovii (Orlova) Hämet‐Ahti (Betulaceae)] leaves collected from unpolluted forests and from heavily polluted industrial barrens surrounding the copper‐nickel smelter in Monchegorsk in north‐western Russia. Population density of S. lapponica, survival of larvae, length of the completed mine, and width of its terminal part did not differ between polluted and unpolluted sites. Females in unpolluted sites only rarely (16%) oviposited on the apical half of the leaf and the larval mortality in mines that started in the apical part of the leaf was 83%. A significantly larger (38%) proportion of mines started in the apical half of the leaves in polluted sites, and the larval mortality in these mines was only 45%. The between‐habitat difference in the choice of the oviposition sites by S. lapponica is the first demonstration of the adaptive plasticity of oviposition behaviour in a leafmining insect. This difference was not explained by specific leaf weight which did not vary within leaves. Larvae mining in polluted leaves extended 25% farther between turns, and the galleries turned more sharply than in unpolluted leaves. This result confirms the abilities of leafmining larvae to evaluate the quality of the ingested food and adjust their behaviour accordingly. Thus, pollution modifies both the preference of S. lapponica females for oviposition sites within a birch leaf and the behaviour of S. lapponica larvae mining these leaves. This is one of the first records of changes in insect behaviour in natural environment disturbed by industrial pollution.     

Effects of leaf litter on the growth of boreal feather mosses: Implication for forest floor development

Question: What is the effect of leaf litter on growth and mortality of feather mosses. Three experiments were conducted to isolate the shading effect from the effect of leaching of soluble compounds from the leaf litter effect on feather moss mortality and growth. Location: Edmonton, Alberta and the northern boreal coniferous forest, west‐central Alberta, Canada. Methods: In a field experiment Populus tremuloides (aspen) leaf litter was applied to beds of feather mosses dominated by Hylocomium splendens. Treatments were one layer of leaves held in place with netting; one layer of leaves coarsely ground, sprinkled over the moss layer; a shade cloth equivalent to one layer of leaves; and a control. In two growth chamber experiments, the application of aqueous extracts of P. tremuloides and Pinus contorta leaf litter and the effect of shade and soluble carbohydrates were tested on the growth and mortality of Ptilium crista‐castrensis. Results: Mortality of Hylocomium was greatest under the intact leaves, followed by the treatments using shade cloth and ground leaves and finally the control. The application of aqueous extracts of aspen leaf litter resulted in senescence or death of nearly all Ptilium shoots compared to no effects for the control or for similar extracts of pine needle litter. Extracts from aspen litter had greater concentrations of phenolic compounds and soluble sugars than pine extracts. Addition of sugars to Ptilium allowed it to grow and accumulate carbohydrates, even in low light conditions. Conclusions: Results suggest that broad‐leaved deciduous overstory species can limit the growth of feather mosses through their leaf litter and by implication affect the humus form, nutrient cycling, and understory composition of these forests.     

Fungal endophytes and phytochemistry of oak foliage: determinants of oviposition preference of leafminers?

Sedentary insect herbivores, such as gallformers and leafminers, are usually non-randomly distributed among and within host plants. Dispersion of these insects is largely a function of female oviposition choice. In field experiments and observations spanning two growing seasons, we tested the hypothesis that selective oviposition on individual leaves within trees by the dominant herbivore of Emory oak, the monophagous leaf-miner Cameraria sp. nov., is determined by the probability of colonization by endophytic fungi. These fungi are alleged to act as plant mutualists by deterring, killing, or inhibiting the growth of insect herbivores. We found that leaves selected by females for oviposition and paired, unmined leaves were equally likely to be colonized by fungal endophytes. Furthermore, condensed and hydrolyzable tannin levels, purported inhibitors of fungal infection, and protein content did not vary between leaves selected by females and unmined leaves, or between leaves with and without endophyte infections. We conclude that female Cameraria do not choose leaves within trees for oviposition on the basis of propensity for endophytic fungal infection or on phytochemical parameters that might indicate probability of future infections. At this spatial scale at least, fungal endophytes do not explain the highly aggregated distribution of Cameraria among leaves and associated costs in terms of increased larval mortality. Fungal endophytes may, nevertheless, affect leafminer dispersion and abundance at larger spatial scales, such as host plant populations or species. We did find, however, that the amount of mining activity on leaves is positively associated with increased colonization by fungal endophytes. We suggest that mining activity increases endophyte fungal infections by facilitating spore germination and hyphal penetration into the leaf or by altering leaf phytochemistry. The facilitation of endophyte colonization by leafmining activity coupled with the lack of predictability of endophyte infections based on leaf phytochemistry and almost 100% infectivity of all oak leaves during sporadic wet years may prevent female leafminers from discriminating leaves for oviposition on the basis of current or future levels of endophytes in leaves.     

Studies on the interference among larvae of the citrus leaf miner,Phyllocnistis citrella stainton (lepidoptera: Phyllocnistidae)

Observation of the citrus leaf miner, Phyllocnistis citrellaStainton suggested that contacts among larvae frequently occur and either of two larvae encountered is sometimes killed by the interference. A model to describe the competitive interactions in the process of interference was constracted with this species. The distribution of hatchling on an area was considered in the model. The model was based on that of encounters in randomly moving particles in two dimensions. First the time when first death occurs was calculated and n hatchlings were reduced to n−1. Further calculation was made to obtain the time that next death occurs. Such calculation was repeated until the number of larvae was reduced to 1 or the area of mine attained to the completed size. By the simulation based on the data observed on the citrus leaf miner, the numbers of survivors were calculated at different hatchling densities and on different leaves in size. Based on this simulation analysis it was suggested that the following characteristics observed in the present studies enable the maximul number of individuals to become adults.

1. When two hatchlings occur on a leaf, they tend to be separated by the midrib. This implies that female moths tend to reject to lay eggs on the area which has already contained the egg.
2. The larva sometimes avoids the contact immediately before it occurs.
3. The larval mortality caused by a contact is reduced with the larval growth. Since the frequency of contacts increases as the mine is enlarged, the change to high survival prevents the larva from high mortality caused by the increase of contacts.
4. The larval survival does not decrease in spite of the reduction of the area available for mining.

     

Precipitation on abscised leaves modulates leaf‐mining beetle (Trachys yanoi) survivorship and population dynamics

1. We clarified the effects of early leaf abscission on the survivorship of the leaf‐mining beetle Trachys yanoi Y. Kurosawa (Coleoptera: Buprestidae) and the underlying mechanism in relation to weather conditions in Japan. Trachys yanoi is an insect pest of zelkova trees [Zelkova serrata (Thunb.) Makino (Rosales: Ulmaceae)]. Larvae burrow into zelkova leaves and feed on leaf tissue, causing early leaf abscission. 2. This study investigated the relationship between the beetle population and weather conditions over 10 years in a zelkova forest. The effects of moisture and temperature on adult emergence from early abscised leaves were examined in the laboratory and in the field. 3. The beetle population in the studied forest was negatively affected by high precipitation levels when the beetles still inhabited early abscised leaves. Fewer adults emerged from early abscised leaves under wet conditions than under dry conditions, in both laboratory and field tests. 4. These results demonstrate that early leaf abscission plays an important role in leaf‐mining beetle survivorship and population dynamics, and that the amount of precipitation when leaf‐mining beetles still inhabit early abscised leaves modulates this effect. 5. Because precipitation when leaf‐mining beetles still inhabit early abscised leaves was mainly driven by an East Asian rainy season front, the beetle population dynamics were affected by the activity of the front.     

Variation in shoot mortality within crowns of severely defoliated <Emphasis Type="Italic">Betula maximowicziana</Emphasis> trees in Hokkaido,northern Japan

To clarify mortality patterns of current-year shoots within the crown of Betula maximowicziana Regel after severe insect herbivory in central Hokkaido, northern Japan, we investigated the degree of defoliation, pattern of shoot development, shoot mortality, and leaf tissue-water relations. One hundred current-year long shoots growing in a B. maximowicziana plantation were observed for defoliation and mortality in June 2002. An outbreak of herbivorous insects (Caligula japonica and Lymantria dispar praeterea) occurred in the stand in mid-to-late June, and the monitored shoots were defoliated to various degrees. Within 1 month of defoliation, some of the severely defoliated shoots had produced new leaves on short shoots that had emerged from axillary buds. Stepwise logistic regression revealed that the probability that current-year long shoots would put out axillary short shoots with leaves is closely related to the degree of defoliation. To evaluate the water relations of the leaves, we determined pressure–volume curves for the leaves that survived the herbivorous insect outbreak and the new leaves that emerged after defoliation. The water potential at turgor loss (Ψ_l,tlp) and the osmotic potential at full turgidity (Ψ_π,sat) were higher for the new leaves than for the surviving leaves, indicating a lower ability to maintain leaf cell turgor against leaf dehydration in the new leaves. Of the 100 shoots, 13 died after the emergence of new leaves. Stepwise logistic regression revealed that the probability that the long shoots would die generally increased with the emergence of new leaves, with increasing shoot height. This result suggests that the combined effect of the vulnerability of newly emerged leaves and low water availability, associated with higher shoot positions within the crown, caused shoot mortality. Based on our results, some possible mechanisms for mortality in severely defoliated B. maximowicziana are discussed.     

Leaf variegation in Caladium steudneriifolium (Araceae): a case of mimicry?

The leaves of Caladium steudneriifolium (Araceae) of the understorey of a submontane rainforest in the Podocarpus National Park (South East Ecuador, 1,060 m a.s.l.) are plain green or patterned with whitish variegation. Of the 3,413 individual leaves randomly chosen and examined in April 2003, two-thirds were plain green, whereas one third were variegated (i.e., whitish due to absence of chloroplasts). Leaves of both morphs are frequently attacked by mining moth caterpillars. Our BLAST analysis based on Cytochrome-c-Oxidase-subunit-1 sequences suggests that the moth is possibly a member of the Pyraloidea or another microlepidopteran group. It was observed that the variegated leaf zones strongly resemble recent damages caused by mining larvae and therefore may mimic an attack by moth larvae. Infestation was significantly 4–12 times higher for green leaves than for variegated leaves. To test the hypothesis that variegation can be interpreted as mimicry to deter ovipositing moths, we first ruled out the possibility that variegation is a function of canopy density (i.e., that the moths might be attracted or deterred by factors unrelated to the plant). Then plain green leaves were artificially variegated and the number of mining larvae counted after 3 months. The results on infestation rate (7.88% of green leaves, 1.61% of the variegated leaves, 0.41% of white manipulated leaves and 9.12% of uncoloured manipulated leaves) suggest that ovipositing moths are deterred by the miner-infestation mimicry. Thus, variegation might be beneficial for the plants despite the implicated loss of photosynthetically active surface.     

Oviposition site preference and larval mortality in a leaf-mining moth

Abstract. 1. The univoltine leaf-mining moth, Lithocolletis quercus Ams., is endemic to Israel, where it spends its 10.5 month larval period feeding only in the leaves of Quercus calliprinos Webb.
2. We compared patterns of egg deposition and sources of larval mortality to test whether oviposition patterns and site preferences confer an enhanced likelihood of larval survival.
3. Dominant sources of larval mortality were premature leaf abscission and death from unknown causes, whereas predation, parasitism and intraspecific interference accounted for relatively little larval mortality.
4. Eggs, and thus mines, were aggregated among leaves of host trees even though premature leaf abscission was positively correlated with density of mines per leaf. Interference competition among larvae was the only other density-dependent mortality factor.
5. Oviposition patterns within leaves mitigated the probability of death from larval interference, and probably also from early leaf abscission.
6. Despite these density-dependent mortality factors, overall probability of larval survival to pupation was independent of initial density of mines on a leaf.
7. The long larval period allows synchrony between oviposition flights and times of predictable resource availability.     

SWATH‐based quantitative proteomics reveals the mechanism of enhanced Bombyx mori nucleopolyhedrovirus‐resistance in silkworm reared on UV‐B treated mulberry leaves

Bombyx mori nucleopolyhedrovirus (BmNPV) is one of the most acute infectious diseases in silkworm, which has led to great economic loss in sericulture. Previous study showed that the content of secondary metabolites in mulberry leaves, particularly for moracin N, was increased after UV‐B irradiation. In this study, the BmNPV resistance of silkworms reared on UV‐B treated and moracin N spread mulberry leaves was improved. To uncover the mechanism of enhanced BmNPV resistance, silkworm midguts from UV‐B treated mulberry leaves (BUM) and moracin N (BNM) groups were analyzed by SWATH‐based proteomic technique. Of note, the abundance of ribosomal proteins in BUM and BNM groups was significantly changed to maintain the synthesis of total protein levels and cell survival. While, cytochrome c oxidase subunit II, calcium ATPase and programmed cell death 4 involved in apoptotic process were up‐regulated in BNM group. Expressions of lipase‐1, serine protease precursor, Rab1 protein, and histone genes were increased significantly in BNM group. These results suggest that moracin N might be the main active component in UV‐B treated mulberry leaves which could improve the BmNPV‐resistance of silkworm through promoting apoptotic cell death, enhancing the organism immunity, and regulating the intercellular environment of cells in silkworm. It also presents an innovative process to reduce the mortality rate of silkworms infected with BmNPV.     

Mines over matter: Effects of foliar particulate matter on the herbivorous insect,Helicoverpa armigera

Coalmines, which are major contributors of particulate matter in the form of coal dust, are expanding globally into rural environments. However, ecological effects on organisms interacting with coal‐dusted foliage in mining landscapes are unknown. We tested how the behaviour, development and survival of a polyphageous insect herbivore, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is affected by consuming tomato leaves Lycopersicon esculentum laden with coal dust. We tested (a) feeding site establishment preference of neonates, (b) feeding behaviour and leaf consumption of late‐instar larvae, (c) survival of neonates and (d) survival and development of late‐instar larvae. We found that coal dust consumption increased the mortality of late‐instar larvae but did not influence their development. Despite long‐term implications for survival, late‐instar larvae did not adjust their feeding behaviour or the amount of leaf material consumed in response to foliar coal dust. Contrastingly, when neonate H. armigera were given a choice, they avoided establishing themselves on the coal‐dusted adaxial surface of leaves. Neonate mortality was 99% within 7 days, with no effect of coal dust. Our study provides the first data on the impact of coal dust on an insect herbivore. This has implications for ecological interactions in landscapes adjoining coalmines.     

LEAF DEMOGRAPHY OF A NEOTROPICAL RAIN FOREST CYCAD,ZAMIA SKINNERI (ZAMIACEAE)

Tropical rain forest understories are extremely light-limited environments. Little is known about the demography of leaves in these habitats. To determine leaf longevity and causes of mortality for a species in the understory of a neotropical rain forest, we studied 634 leaves on 173 individuals of the cycad shrub Zamia skinneri for 10 yr at the La Selva Biological Station, Costa Rica. Five different seasonal cohorts of leaves were followed. No significant differences among cohorts were found in median leaf longevity, but the cohorts did differ in the proportion of leaves dying in annual intervals from <1 to ≥6 yr. Median minimum time alive for all leaves was 4.6 yr. Epiphyll coverage increased from 0% in the first year of life to 75%-100% by year 4. Leaf mortality was well described by two separate exponential functions, approximately 10% mortality/yr until year 4, then abruptly increasing to ca. 51%/yr. Of 625 leaf deaths, 77.0% were due to unexplained causes, 16.5% to physical damage by falling litter, 4.8% to attacks by larvae of the lycaenid butterfly Eumaeus minyas, and 1.8% to other causes. Leaf longevity was positively correlated with leaf size. Individuals of Z. skinneri frequently survive more than a century in very dark understory conditions. We suggest that leaf longevity in these circumstances is determined by the inevitable deterioration in leaf carbon balance due to leaf aging and increasing epiphyll coverage, and by loss due to physical damage and attacks by the specialist herbivore.     

Leaf mines: their effect on leaf longevity

Summary The effects of a number of factors, notably leaf mining insects, on the longevity of beech and holm oak leaves have been studied. The regular monitoring of individually labelled leaves was complemented by analysis of leaf fall data. Both methods confirm that these mining insects have only a slight impact on their host trees. The presence of first generation Phyllonorycter maestingella mines on beech leaves and winter generation P. messaniella mines on holm oak leaves accelerates leaf loss. Beech leaves mined by second generation P. maestingella and Rhynchaenus fagi did not show this accelerated loss. Their patterns of leaf fall can be explained by within-tree variation in both mine distribution and the timing of leaf fall. It is argued that this premature leaf fall is a damage response, and is not an attempt by the tree to regulate miner numbers.     

Defensive effects of extrafloral nectaries in quaking aspen differ with scale

The effects of plant defenses on herbivory can differ among spatial scales. This may be particularly common with indirect defenses, such as extrafloral nectaries (EFNs), that attract predatory arthropods and are dependent on predator distribution, abundance, and behavior. We tested the defensive effects of EFNs in quaking aspen (Populus tremuloides Michx.) against damage by a specialist herbivore, the aspen leaf miner (Phyllocnistis populiella Cham.), at the scale of individual leaves and entire ramets (i.e., stems). Experiments excluding crawling arthropods revealed that the effects of aspen EFNs differed at the leaf and ramet scales. Crawling predators caused similar reductions in the percent leaf area mined on individual leaves with and without EFNs. However, the extent to which crawling predators increased leaf miner mortality and, consequently, reduced mining damage increased with EFN expression at the ramet scale. Thus, aspen EFNs provided a diffuse defense, reducing damage to leaves across a ramet regardless of leaf-scale EFN expression. We detected lower leaf miner damage and survival unassociated with crawling predators on EFN-bearing leaves, suggesting that direct defenses (e.g., chemical defenses) were stronger on leaves with than without EFNs. Greater direct defenses on EFN-bearing leaves may reduce the probability of losing these leaves and thus weakening ramet-scale EFN defense. Aspen growth was not related to EFN expression or the presence of crawling predators over the course of a single season. Different effects of aspen EFNs at the leaf and ramet scales suggest that future studies may benefit from examining indirect defenses simultaneously at multiple scales.     

Oviposition,larval survival and leaf damage by the willow leaf blotch miner,Micrurapteryx salicifoliella,in relation to leaf trichomes across 10 Salix species

1. Foliar trichomes clearly reduce chewing damage and efficiency of movement by some insect herbivores, but the effect of trichomes on insect oviposition is less well characterised. Trichomes are likely to have particularly strong, negative effects on species that require secure attachment of the egg to the leaf epidermis for successful transition to the feeding stage – a group that includes many leaf mining insects. 2. One such species, Micrurapteryx salicifoliella, must initially enter leaf cells directly from an egg adhered to the cuticle, but later instars can move between leaves and initiate new mines from the leaf exterior. 3. Natural patterns of occurrence by M. salicifoliella were quantified on 10 sympatric Salix species varying in trichome expression to test whether trichomes were associated with reduced oviposition, larval survival and leaf damage. 4. Mean egg density and leaf mining damage were negatively related to mean trichome density across Salix species. Survival of M. salicifoliella from egg to pupa was positively related to trichome density, suggesting that initiation of new mines by late‐instar larvae was not adversely affected by trichomes. There was no evidence that trichomes benefited leaf miner larvae indirectly by decreasing density‐dependent mortality; rather, the positive relationship between trichome density and larval survival may reflect less effective chemical defence by Salix species expressing high trichome density. 5. The results suggest that foliar trichomes serve as an effective defence against M. salicifoliella by deterring oviposition, but do not reduce the survivorship of those individuals that successfully transition from egg to larva.     

采煤塌陷影响下土壤含水量变化对柠条气孔导度、蒸腾与光合作用速率的影响

采煤塌陷引起的土壤环境因子的变化对矿区植物生长的影响越来越受到人们的关注,气孔导度、蒸腾与光合作用作为环境变化响应的敏感因子,研究植物气孔导度、蒸腾与光合作用的变化是揭示荒漠矿区自然环境变化及其规律的重要手段之一。研究采煤塌陷条件下植物光合生理的变化是探究煤炭开采对植物叶片水分蒸腾散失和CO_2同化速率影响的关键环节,是探讨采煤塌陷影响下植物能量与水分交换动态的基础,而采煤矿区植物叶片气孔导度、蒸腾与光合作用速率对采煤塌陷影响下土壤含水量变化的响应如何尚不清楚。选取神东煤田大柳塔矿区52302工作面为实验场地,以生态修复物种柠条为研究对象,对采煤塌陷区和对照区柠条叶片气孔导度、蒸腾和光合作用速率以及土壤体积含水量进行监测,分析了采煤塌陷条件下土壤含水量的变化以及其对柠条叶片气孔导度、蒸腾与光合作用速率的影响。结果显示:(1)煤炭井工开采在地表形成大量裂缝,破坏了土体结构,潜水位埋深降低,土壤含水量均低于沉陷初期,相对于对照区,硬梁和风沙塌陷区土壤含水量分别降低了18.61%、21.12%;(2)柠条叶片气孔导度、蒸腾和光合作用速率均与土壤含水量呈正相关关系;煤炭开采沉陷增加了地表水分散失,加剧了土壤水分胁迫程度,为了减少蒸腾导致的水分散失,柠条叶片气孔阻力增加,从而气孔导度降低,阻碍了光合作用CO_2的供应,从而导致柠条叶片光合作用速率的降低,蒸腾速率也显著降低。     

Colonization and lignin decomposition of Camellia japonica leaf litter by endophytic fungi

Endophytic fungi occur on various types of leaf litter, but few studies have been done on their roles as saprophytes in decomposition. This study examined the succession of fungi in live, newly shed, and decomposing leaves at 2 months of decomposition of Camellia japonica and chemical changes in decomposing leaves colonized by endophytes. Coccomyces nipponicum, Lophodermium sp., Geniculosporium sp. 1, and Colletotrichum gloeosporioides were isolated from living leaves. Coccomyces nipponicum and Lophodermium sp. were also isolated frequently from newly shed and decomposing leaves. These two fungi caused a decrease of lignin content and bleaching in decomposing leaves under field and laboratory conditions. Total hyphal length in decomposing leaves was higher in bleached portions than in surrounding nonbleached portions, which probably reflected the early onset of hyphal growth of endophytes inside leaf tissue at leaf senescence or death. Incubation of newly shed leaves that were sterilized to exclude previously established endophytes resulted in no occurrence of bleached portions in decomposing leaves on the forest floor. This result indicated that these endophytes were incapable of colonizing leaves directly after litterfall and that the persistence of endophytes from live leaves was crucial for their colonization in decomposing leaves.     

Larval performance in relation to oviposition site preference in olive kernel moth (Prays oleae Bern., Yponomeutidae,Praydina)

1 The tri‐voltine moth Prays oleae Bern. spends its larval stages on the native olive tree (Olea europaea L. var. sylvestris Brot. and five cultivars, Oleaceae) mining the leaves, the flowers and the fruits in each generation; it seldom switches to other native or introduced confamilial plant species. 2 In this study the pattern of oviposition of the olive moth was examined in olive fields and natural vegetation, in relation to in situ recruitment as an outcome of processes such as density dependence or risk spreading. 3 Larval body size (width of epicranial sclerites) was also examined and compared between host substrates, years and morphological, physiological, ecological and nutritional attributes of the host. 4 The factors influencing the oviposition pattern of the olive moth such as the carbon/nitrogen ratio, number of flowers, branch length and previous leaf damage were ranked differently in different cultivars. 5 ‘Hot spots’, i.e. olive trees or parts of trees receiving a high egg load, were found to be the result of in situ recruitment. 6 Physiological mortality among first instar larvae was significantly negatively correlated with the number of oviposited upon leaves; suggesting that the adult selects for oviposition the best available substrate. 7 As adult moths selected leaves with minimal probability of abscission for oviposition, leaf abscission was not a major mortality factor, although first instar larvae reduced leaf longevity. 8 Host quality did not affect all larval stages in the same way. 9 The more nutritionally poor the substrate, the longer the duration of the larval stage feeding on it. The phenological timing of the insect life stages very closely tracks the phenological phases of its host plant, primarily focusing on the most nutritious host stage in terms of larval performance.     

Geographic variation in vascular mortality in eurasia: Relationship between mortality variables and risk factors

This study was based on a sample of 68 populations from 42 countries of Eurasia. Most of the data were from the MONICA Project, while additional information was from the abundant literature. Mortality rates (from cardiovascular, cerebrovascular and ischaemic heart diseases, and death rate from all causes) and related to them potential risk factors (systolic and diastolic blood pressure, total serum cholesterol and body mass index) were described for men and women, separately for 5 age cohorts, ranging between 25 and 64 years. The results showed that, in contrast to the studies carried out on theintrapopulational level, in our work risk factors did not demonstrate any strong association with mortality rate variables. Moreover, it was found that the vascular mortality on theinterpopulational level explains between 57% and 71% in total mortality and could serve as a quite fair indicator of the populational well-being in general. Although mortality rate from vascular diseases in women was much lower than in man of equal ages, geographic variation of the above mentioned death rates has showed a very similar pattern in the two sexes: the death rate is high in women when it is high in men.     

Interactions of colonisation density and leaf environments on survival of Trioza eugeniae nymphs

1. Female eugenia psyllids Trioza eugeniae oviposit on the margins of expanding young Syzygium paniculatum leaves. The developing nymphs, feeding within pit‐shaped galls on the leaves, cause the leaves to become curled and deformed. The degree of leaf curling was correlated positively with densities of T. eugeniae nymphs. 2. High relative humidity increased persistence of nymphs on leaves at low insect densities, but persistence did not differ between high or low relative humidity conditions when nymphal densities were high and leaves were greatly curled. 3. Direct insolation increased nymphal mortality. Nymphs on the abaxial leaf surface in the direct sun had lower mortality than similarly exposed nymphs on the adaxial leaf surface. 4. Field populations showed high preference for abaxial leaf surfaces and a stronger preference for shaded adaxial surfaces than for exposed adaxial surfaces. 5. Adverse environmental conditions of direct insolation and low relative humidity may be mitigated by leaf curl associated with moderate populations, however competition at high nymphal density supersedes any potential benefit arising from leaf curling and has a negative effect on nymphal survival.