Cabbage waxes affect Trissolcus brochymenae response to short-range synomones

We show that induced synomones, emitted as a consequence of Murgantia histrionica activity on Brassica oleracea, are adsorbed by the epicuticular waxes of leaves and perceived by the egg parasitoid Trissolcus brochymenae. Leaves were exposed to M. histrionica females placed on the abaxial leaf surface. After 24 h, the leaves were treated mechanically using gum arabic, or chemically using chloroform, on the adaxial surface, and finally the adaxial surface was assayed with T. brochymenae by two-choice tests in a closed arena. Wasp females responded to mechanically dewaxed cabbage leaf portions with feeding punctures and footprints （Ff） and with feeding punctures, oviposition and footprints （FOr）, showing no effect of wax removal. In contrast, the removal of the epicuticular waxes from leaf portions close to FOf, and from leaves with oviposition and footprints （Of）, determined the lack of responses by T. brochymenae. Solvent extracts of different treatments were bioassayed, but only FOr triggered parasitoid response. Thus the detection of oviposition-induced synomones by the parasitoid depends on their adsorption by the epicuticular waxes. Mechanical wax removal from leaf portions contaminated with host footprints （f） also determined a lack of wasp responses, suggesting that the footprints might trigger the induction of a ＂footprint-induced synomone＂ adsorbed onto the epicuticular waxes and exploited by the parasitoid. Leaf portions with the abaxial lamina previously dewaxed and then contaminated by footprints （D＋f） of M. histrionica did not affect the parasitoid response, indicating that the abaxial epicuticular waxes are not directly involved in the chemicals induced by M. histrionica footprints.     

Anatomical and morphological parameters of leaves and leaf petioles of Actinidia deliciosa

Differences in anatomy and morphology of the kiwifruit leaves and leaf petioles might play a considerable role in the sex-determination. Three months after bud break (June), the kiwifruit leaves of both male and female plants, grown on the vegetative and generative shoots showed different leaf area (128.6 ± 13.45 cm2 in male and 104.5 ± 4.02 cm2 in female plants) and shape. The most frequently leaf shape was determined as "folium cordatum" and "folium rotundato-cordatum". Higher values of total leaf thickness of the female leaves (190 ± 3.84 μm) in comparison to male leaves (174 ± 3.52 μm) were estimated, resulting in the thicker adaxial leaf epidermis and especially in thicker palisade parenchyma in female leaves (136 ± 2.76 μm in comparison to 104 ± 1.61 μm in male leaves). Typically bifacial leaves were observed in both male and female leaves. Anomocytic stomata in hypostomatic leaves were found. The reticulate venation appears to be the main type of leaf venation. Stalked stellate multicellular trichomes on the abaxial leaf side were frequently observed in the leaves of both sexes. No important differences between male and female plants were found in the structures of vascular system in leaves and leaf petioles. Thus leaf thickness and surface morphology of adaxial leaf epidermis can be considered as important structural parameters in the sex determination. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of leaf shape plasticity on leaf surface temperature北大核心CSCD

Aims The shape plasticity of plant leaves is an important survival strategy to high temperature and drought in arid region, yet reliable evidences are insufficient to validate the fundamental concepts. Our objective was to demonstrate the specific effects of leaf morphology on leaf surface temperature. Methods Infrared thermal images were processed to determine the leaf temperature and shape parameters of simulated and actual leaf shape. Microclimatic conditions were recorded using a automatic weather station near the sampling plot, including wind speed, radiation and air temperature. Important findings Under the drought and high temperature, the plasticity of leaf shape appeared an important measure to regulate leaf temperature, except leaf transpiration. The exchange rates of matter and energy between leaves and the environment were enhanced by smaller leaves that effectively decreased leaf temperature. With low wind speed and high temperature, leaf surface temperature decreased 2.1 °C per 1 cm reduction in leaf width. However, leaf surface temperature of a simulated leaf decreased 0.60–0.86 °C per 1 cm reduction in leaf width. Results from this study will help us to understand plant adaptability and survival strategy in arid region. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.     

Effects of copper on the growth, photosynthesis and nutrient concentrations of Phaseolus plants

Bean plants (Phaseolus vulgaris L. var. Zargana Kavala) were grown under conditions of increasing Cu concentrations in the growth medium (0.5-160.5 μM). Generally, the Cu concentrations between 0.5-1.5 μM were deficient, 1.5-10.5 μM were optimal, and 10.5-160.5 μM were toxic to plant growth. The Cu toxicity was associated with marked increases in plant tissue Cu concentrations. Under the Cu-deficient and optimal growth conditions, Cu was located primarily in the leaves. Under Cu toxicity, it was primarily sequestered in the roots. With increasing Cu in the growth medium, there was a positive correlation between Cu concentrations in the roots, stems and leaves, Ca in the roots, and K and Mg in the leaves. In contrast, Ca concentrations in the leaves and stems showed a negative correlation. The chlorophyll (Chl) concentration increased with increasing leaf Cu concentration, however, the Chl a/b ratio decreased. Since with an increasing leaf Cu concentration the leaf area decreased more markedly than the leaf dry mass, the net photosynthetic rate (PN) per leaf area increased and per dry mass decreased. The increase in PN per leaf area was almost entirely accounted for by the increase in Chl concentration. The initial Chl fluorescence (F0) increased with increasing leaf Cu concentration. The ratio of variable to maximum fluorescence (Fv/Fm) under Cu toxicity decreased. The half-time for the rise from F0 to Fm (t1/2) remained relatively unchanged with increasing leaf Cu concentration. Therefore the Cu-stress caused a small decrease in the efficiency of photosystem 2 photochemistry, but its primary effect was on growth. This revised version was published online in June 2006 with corrections to the Cover Date.     

Metal concentrations of insects associated with the South African Ni hyperaccumulator Berkheya coddii （Asteraceae）

The high levels of some metals in metal hyperaccumulator plants may be transferred to insect associates. We surveyed insects collected from the South African Ni hyperaccumulator Berkheya coddii to document whole-body metal concentrations （Co, Cr, Cu, Mg, Mn, Ni, Pb, Zn）. We also documented the concentrations of these metals in leaves, stems and inflorescences, finding extremely elevated levels of Ni （4 700-16 000μg/g） and high values （5-34μg/g） for Co, Cr, and Pb. Of 26 insect morphotypes collected from B. coddii, seven heteropterans, one coleopteran, and one orthopteran contained relatively high concentrations of Ni （〉 500μg/g）. The large number of high-Ni heteropterans adds to discoveries of others （from California USA and New Caledonia） and suggests that members of this insect order may be particularly Ni tolerant. Nymphs of the orthopteran （Stenoscepa） contained 3 500 μg Ni/g, the greatest Ni concentration yet reported for an insect. We also found two beetles with elevated levels of Mg （〉 2 800 μg/g）, one beetle with elevated Cu （〉 70 μg/g） and one heteropteran with an elevated level of Mn （〉 200 μg/g）. Our results show that insects feeding on a Ni hyperaccumulator can mobilize Ni into food webs, although we found no evidence of Ni biomagnification in either herbivore or carnivore insect taxa. We also conclude that some insects associated with hyperaccumulators can contain Ni levels that are high enough to be toxic to vertebrates.     

Response of Solanum tuberosum to Myzus persicae infestation at different stages of foliage maturity

Young leaves of the potato Solanum tuberosum L. cultivar Kardal contain resistance factors to the green peach aphid Myzuspersicae （Sulzer） （Hemiptera： Aphididae） and normal probing behavior is impeded. However, M. persicae can survive and reproduce on mature and senescent leaves of the cv. Kardal plant without problems. We compared the settling ofM. persicae on young and old leaves and analyzed the impact of aphids settling on the plant in terms of gene expression. Settling, as measured by aphid numbers staying on young or old leaves, showed that after 21 h significantly fewer aphids were found on the young leaves. At earlier time points there were no difference between young and old leaves, suggesting that the young leaf resistance factors are not located at the surface level but deeper in the tissue. Gene expression was measured in plants at 96 h postinfestation, which is at a late stage in the interaction and in compatible interactions this is long enough for host plant acceptance to occur. In old leaves of cv. Kardal （compatible interaction）, M. persicae infestation elicited a higher number of differentially regulated genes than in young leaves. The plant response to aphid infestation included a larger number of genes induced than repressed, and the proportion of induced versus repressed genes was larger in young than in old leaves. Several genes changing expression seem to be involved in changing the metabolic state of the leaf from source to sink.     

Assessing the Suitability of Various Physiological Traits to Screen Wheat Genotypes for Salt Tolerance

Success of improving the salt tolerance of genotypes requires effective and reliable screening traits in breeding programs.The objective was to assess the suitability of various physiological traits to screen wheat genotypes for salt tolerance.Thirteen wheat genotypes from Egypt,Germany,Australia and India were grown in soil with two salinity levels(control and150mmol/L NaCl)in a greenhouse.The physiological traits(ion contents in leaves and stems,i.e.Na~ ,Cl~-,K~ ,Ca~(2 )),theratios of K~ /Na~ and Ca~ /Na~ in the leaves and stems,net photosynthesis rate,stomatal conductance,transpiration rate,chlorophyll content(SPAD value),and leaf water relations,were measured at different growth stages.The physiologicaltraits except for Na~ and Cl~-in stems and the leaf transpiration rate at 150 mmol/L NaCI showed a significant genotypicvariation,indicating that the traits that have a significant genotypic variation may be possibly used as screening criteria.According to the analysis of linear regression of the scores of the physiological traits against those of grain yield,however,the physiological traits of Ca~(2 )and Ca~(2 )/Na~ at 45 d and final harvest with the greatest genotypic variation were ranked atthe top.From a practical and economic point of view,SPAD value should be considered to be used as screening criteriaand/or there is a need to develop a quick and practical approach to determine Ca~(2 )in plant tissues.     

Foliar modifications induced by inhibition of polar transport of auxin

The effects of auxin polar transport inhibitors,9-hydroxy-fluorene-9-carboxylic acid (HFCA);2,3,5-triiodobenzoic acid(TIBA) and trans-cinnamic acid (CA) on leaf pattern formation were investigated with shoots formed from cultured leaf explants of tobacco and cultured pedicel explants of Orychophragmus violaceus,and the seedlings of tobacco and Brassica chinensis,Although the effective concentration varies with the inhibitors used,all of the inhibitors induced the formation of trumpet-shaped and/or fused leaves.The frequency of trumpet-shaped leaf formation was related to the concentration of inhibitors in the medium.Histological observation of tobacco seedlings showed that there was only one main vascular bundle and several minor vascular bundles in normal leaves of the control,but there were several vascular bundles of more or less the same size in the trumpet-shaped leaves of treated ones.These results indicated that auxin polar transport played an important role on bilateral symmetry of leaf growth.     

Bionic Leaf Simulating the Thermal Effect of Natural Leaf Transpiration

We proposed a kind of bionic leaf to simulate the thermal effect of leaf transpiration. The bionic leaf was firstly designed to be composed of a green coating, a water holding layer, a Composite Adsorbent （CS） layer and an adsorption-desorption rate controlling layer. A thermophysical model was established for the bionic leaf, and the dynamic simulation results reveal that the water holding layer is not necessary; a CS of high thermal conductivity should be selected as the CS layer; the adsorp- tion-desorption rate controlling layer could be removed due to the low adsorption-desorption rate of the CS; and when CaC12 mass fraction of the CS reaches 40%; the bionic leaf could simulate the dynamic thermal behavior of the natural leaf. Based on the simulation results, we prepared bionic leaves with different CaC12 content. The thermographies of the bionic leaf and the natural leaf were shot using the Infrared Thermal Imager. The measured average radiative temperature difference between the bionic and natural leaves is less than 1.0 ℃.     

Cotton Leaf Curl Virus： Ionic Status of Leaves and Symptom Development

In the present study, the relationship between the nutritional status of leaves and the development of symptoms of cotton leaf curl virus （CLCuV） in two cotton （Gossypium hirsutum L.） cuItlvars （I.e. CIM-240 and S-12） was Investigated. The incidence of disease attack was found to be 100% In the S-12 cuItlvar and 16% in the CIM-240 cuItivar. Geminivirus particles in infected leaves were confirmed by transmission electron microscope examination of highly specific geminivirus coat protein antlsera-treated cell sap. The CLCuV Impaired the accumulation of different nutrients in both cuItivars. A marked decrease in the accumulation of Ca^2＋ and K^＋ was observed in infected leaves. However, the disease had no effect on leaf concentrations of Na^＋, N, and P. It was observed that the curling of leaf margins in CLCuV-Infected plants was associated with the leaf Ca^2＋ content; leaf curling was severe in plants with a significant reduction In Ca^2＋ content. Moreover, leaf K＆＋ content was found to be associated with resistance/susceptibility to CLCuV infection.     

Feeding patterns of monophagous,oligophagous, and polyphagous insect herbivores: The effect of resource abundance and plant chemistry

Summary Leaf tissue preferences of monophagous, oligophagous, and polyphagous insect herbivores were determined using young and mature leaf tissue abundances and herbivore feeding observations. Larvae of monophagous and oligophagous herbivores preferred young leaf tissues while, overall, larvae of polyphagous species preferred mature leaves of their various host plants. Even though a species is often polyphagous over its geographical range, larvae from local populations may be very specialized in their diet. When this occurs these specialized larvae prefer the more nutritious and perhaps more toxic young leaves of some of their host plants. Resource abundance and plant chemistry are discussed as major factors influencing herbivore feeding patterns.     

Chenopod salt bladders deter insect herbivores

Trichomes on leaves and stems of certain chenopods (Chenopodiaceae) are modified with a greatly enlarged apical cell (a salt bladder), containing a huge central vacuole. These structures may aid in the extreme salt tolerance of many species by concentrating salts in the vacuole. Bladders eventually burst, covering the leaf in residue of bladder membranes and solid precipitates. The presence of this system in non-halophytic species suggests additional functions. I tested the novel hypothesis that these bladders have a defensive function against insect herbivores using choice, no choice, and field tests. Generalist insect herbivores preferred to feed on leaves without salt bladders in choice tests. In no choice tests, herbivores consumed less leaf matter with bladders. In a field test, leaves from which I had removed bladders suffered greater herbivory than adjacent leaves with bladders. Solutions containing bladders added to otherwise preferred leaves deterred herbivores, suggesting a water-soluble chemical component to the defense. This bladder system has a defensive function in at least four genera of chenopods. Salt bladders may be a structural defense, like spines or domatia, but also have a chemical defense component.     

Effects of insect attack to stems on plant survival,growth, reproduction and photosynthesis

Studies of insect herbivory have mostly focused on leaf‐feeding even though most woody plant biomass is stem tissue. Attack to stems has the potential to be more detrimental to plant performance than attack to leaves. Here we asked how severe is the impact of insect stem herbivory on plant performance. We quantify the effect of insect stem herbivory via a meta‐analysis of 119 papers in 100 studies (papers by the same authors were treated as the same study). These studies involved 92 plant species and 70 species of insect herbivore (including simulated herbivory). Attack to plant stems reduced plant performance by an average of approximately 22%. Stem herbivory had greatest impacts on plant and branch survival, which was reduced by 63%. Measures of plant reproduction and vegetative biomass were reduced by 33% and 16% respectively, while measurements of photosynthetic rate were not significantly different between plants with and without stem herbivore attack. Stem herbivory led to a decline in leader performance but an increase in performance of laterals, highlighting the importance of plant compensation. Juvenile plants were more severely affected by stem herbivory than adult plants, and studies conducted in greenhouses found more severe effects than studies conducted in the field. Stem herbivory did not have a significant effects on any of the non‐performance responses measured (defence compounds, SLA, root:shoot, phenology and plant carbon and nitrogen). We compare our results with results from various meta‐analyses considering herbivory on other plant parts. The impact of insect herbivory to stems on plant performance appears at least as severe as insect herbivory to roots and leaves, if not more.     

Seasonality of insect herbivory on the leaves of Neoboutonia macrocalyx in the Kibale National Park, Uganda

The seasonality of herbivory on the leaves of Neoboutonia macrocalyx Pax. in Kibale Forest National Park, Uganda, was studied. A total of 2929 fallen leaves was collected during 15 months under randomly-selected trees in three different habitats; natural forest and two selectively cut forest sites. The percentage of leaf area eaten and leaf size were estimated. Leaf herbivory was highly seasonal and correlated with rainfall in the previous 2 months, but less than 100 mm monthly rainfall had no effect. There was no correlation between leaf size and rainfall. Although Kibale Forest has two wet seasons, insect feeding on leaves had only one peak during the major rainy season from September to December. Three to four months after peak herbivory, leaves had very low rates of insect damage. Habitat had only a small effect on the amount of insect feeding. The sampling time accounted for 71% of variation in leaf herbivory. New leaves were formed continuously year-round. The constant leaf production by Neoboutonia trees may be an adaptation to escape generalist herbivorous insects which might be synchronized with the major wet season when the leaf flush of the most other deciduous species occurs. Thus, the availability of fresh leaves is not acting as a regulating factor in seasonality of Neoboutonia herbivory.     

Effects of leaf and sap feeding insects on photosynthetic rates of goldenrod

Summary Herbivory can alter the balance between sources and sinks within a plant, and changes in the source-sink ratio often lead to changes in plant photosynthetic rates. We investigated how feeding by three insect herbivores affected photosynthetic rates and growth of goldenrod (Solidago altissima). One, a phloem-sap feeding aphid (Uroleucon caligatum), creates an additional sink, and the other two, a leaf-chewing beetle (Trirhabda sp.) and a xylem-sap feeding spittlebug (Philaenus spumarius) both reduce source supply by decreasing leaf area. Plants were grown outside in large pots and insects were placed on them at predetermined densities, with undamaged plants included as controls. All insects were removed after a 12-day feeding period. We measured photosynthetic rates both of damaged leaves and of undamaged leaves that were produced after insect removal. Photosynthetic rates per unit area of damaged leaves were reduced by spittlebug feeding, but not by beetle or aphid feeding. Conductance of spittlebugdamaged leaves did not differ from controls, but internal carbon dioxide concentrations were increased. These results indicate that spittlebug feeding does not cause stomatal closure, but impairs fixation within the leaf. Effects of spittlebug feeding on photosynthetic rates persisted after the insects were removed from the plants. Photosynthetic rates per unit area of leaves produced after insect removal on spittlegug-damaged plants were lower than control levels, even though the measurements were taken 12 days after insect removal. The measurement leaf on spittlebugdamaged plants was reduced in area by 27% relative to the controls, but specific leaf area (leaf area/leaf weight) was increased by 18%. Because of the shift in specific leaf area, photosynthetic rates were also examined per unit leaf weight, and when this was done there were no significant differences between control and spittlebug-damaged plants. Beetle and aphid feeding had no effects on the photosynthetic rate of the leaves produced after insect removal. Plant relative growth rates (in terms of height) were reduced by spittlebugs during the period that the insects were feeding on the plants. Relative growth rates of spittlebug-damaged plants were increased above control levels after insect removal, but these plants were still shorter than controls 17 days after insect removal. Beetles and aphids did not affect plant relative growth rates or plant height. Feeding by both spittlebugs and beetles reduced leaf area, and the effect of the spittlebug was more severe than that of the beetle. These results show that effects of herbivory on photosynthetic rates cannot be predicted simply by considering changes in the source-sink ratio, and that spittlebug feeding is more damaging to the host plant than beetle or aphid feeding.     

莲草直胸跳甲的空间选择与性别分化

【背景】莲草直胸跳甲是空心莲子草的专一性天敌,成功地大量繁殖是其大规模应用于空心莲子草生物防治的必要条件,为了更好地开展莲草直胸跳甲的室内大量繁殖,明确其不同虫态对空心莲子草空间的选择性具有重要意义。【方法】本研究调查了莲草直胸跳甲成虫取食与产卵、幼虫取食、老熟幼虫化蛹的空间选择性,并分析了空心莲子草茎秆直径对幼虫化蛹空间选择、蛹羽化率和羽化成虫性别分化的影响。【结果】雌雄成虫均嗜好栖息于空心莲子草幼嫩的顶叶,位于顶叶的雌、雄成虫数量分别占整株的62.9%和63.3%;成虫偏好将卵产在第2节叶片上,比例高达41.2%;幼虫主要集中于上部3节的叶片上取食,占84.8%;老熟幼虫化蛹前在茎秆上蛀孔后钻入茎秆中化蛹,其不在第1节茎秆内化蛹,化蛹主要选择在3～5节,其中在第4节茎秆内化蛹量最高,达1.0头.节-1;老熟幼虫在1～5节茎秆内的化蛹量与空心莲子草茎秆直径具有显著相关性（y=-19.209x2＋16.66x＋2.6737,R2=0.841）;羽化成虫的雌雄性比则与茎秆直径呈显著正相关（y=5.5704x-1.1718,R2=0.914）。【结论与意义】莲草直胸跳甲成虫和幼虫均偏好在空心莲子草上部的叶片取食,老熟幼虫化蛹则偏好中部较粗壮的茎节,因此,培育茎秆较粗且老化程度较低的空心莲子草是实现莲草直胸跳甲大量饲养的重要途径。本研究可为优化人工大量饲养繁殖莲草直胸跳甲的条件提供数据支持。     

Diamondback moth oviposition: effects of host plant and herbivory

The oviposition behaviour of Plutella xylostella L. (Lepidoptera: Plutellidae) on Chinese cabbage (Brassica rapa L. Pekinensis, cv. Wombok), canola (Brassica napus L. cv. Thunder TT), and cabbage (Brassica oleracea L. Capitata, cv. sugarloaf) (Brassicaceae) was studied in the laboratory. In no‐choice experiments moths laid most eggs on the stems and lower three leaves of cabbage plants, the lower three leaves of canola plants, but on the upper three leaves of Chinese cabbage plants. The effects of conspecific herbivore damage to foliage could be replicated by mechanical damage. When foliage was damaged, injured cabbage and canola plants were preferred for oviposition over intact conspecifics, whereas injured Chinese cabbage plants were less preferred than intact conspecifics. However, when root tissue was damaged, intact cabbage and canola plants were preferred over injured conspecifics, whereas moths did not discriminate between root‐damaged and intact Chinese cabbage plants. Injury to upper leaves significantly affected the intra‐plant distribution of eggs. In cabbage and canola plants, injury to leaf 6 significantly increased the number of eggs laid on this leaf, resulting in a significant decrease in the number of eggs laid on the lower foliage/stem of plants, whereas in Chinese cabbage plants it significantly decreased the number of eggs laid on leaf 6. Following oviposition on intact plants, neonate larvae established the vast majority of feeding sites on leaves 5–8 in all three host plants, indicating that larvae moved a considerable distance from preferred oviposition sites in cabbage and canola plants. The growth rate of neonates fed on leaf‐6 tissue was significantly greater than that of those fed on leaf‐1 tissue; >90% of larvae completed development when fed exclusively on leaf‐6 tissue but no larvae completed development when fed exclusively on leaf‐1 tissue. The study demonstrates the complex and unpredictable interactions between P. xylostella and its host plants and provides a basis from which we can begin to understand observed distributions of the pest in Brassica crops.     

无翅茶蚜对茶树挥发物的触角电生理和行为反应

分别使用昆虫触角电位仪(EAG)和四臂嗅觉仪,测定了无翅茶蚜Toxopteraaurantii Boyer对14种茶树挥发性化合物、14种挥发物中"绿叶气味"组成的混合物(GLV)、14种挥发物的混合物(ACB)、以及新鲜嫩叶、芽、嫩茎、成叶和茶蚜为害嫩叶(ADYL)的EAG反应和行为反应。ACB引出最大的EAG反应值,茶树挥发物主要组分Z-3-己烯-1-醇、E-2-己烯醛、n-己醇、水杨酸甲酯和苯甲醇也引起较大的EAG反应值。4种正常茶梢的器官也引出较大的EAG反应,以嫩叶最强、依次为芽、嫩茎和成叶。有趣的是ADYL引出弱的负的EAG值。用嗅觉仪进行的生物测定表明,嫩叶以及主要的茶梢挥发性成分乙酸-Z-3-己烯酯、水杨酸甲酯、E-2-己烯-1-醇和Z-3-己烯-1-醇等也具有较强引诱活性。研究显示无翅茶蚜可能利用茶梢挥发物作为利它素而寻觅适宜的取食场所,如茶树嫩梢。     

Insect herbivory and plant defense on ginkgoalean and bennettitalean leaves of the Middle Jurassic Daohugou Flora from Northeast China and their paleoclimatic implications

Interactions between terrestrial arthropods and plants play a significant role in terrestrial ecosystems. Research on plant–insect interactions through geologic time provides valuable information for studying insect behavior and plant structure, understanding their coevolution, as well as analyzing climate change. In this paper, we choose fossil ginkgoalean and bennettitalean leaves as the plant hosts to study insect herbivory in the Middle Jurassic Daohugou area. Seven damage types of four functional feeding groups have been identified. Of the four functional feeding groups, margin feeding is the most common, indicating an abundance of insects with chewing mouthparts. Ginkgoalean leaves, probably because of their chemical defense, suffered less severe insect damage than bennettitalean leaves. Physical defense has also been observed in various genera of the bennettitalean leaves. Significantly, leaves of Anomozamites had a shaggy indumentum on the abaxial leaf surface and long stiff hairs along the rachis protecting them from insect herbivory. Our results indicate that the climate in the Middle Jurassic of the Daohugou area was relatively warm and humid. This work contributes to the study of plant–insect coevolution in the Daohugou Biota and provides more proxy data for understanding the Middle Jurassic paleoclimate and paleoenvironment in Daohugou area.     

Influence of previous frost damage on tree growth and insect herbivory of Eucalyptus globulus globulus

The plant stress hypothesis suggests that some herbivores favour stressed plants, whereas the plant vigour hypothesis proposes that other herbivores prefer vigorous plants. The effects of a prior stress, that of frost damage, were examined on the subsequent growth of Eucalyptus globulus globulus and on the response of insect herbivores. Frost damage affected tree growth by reducing new leaf area and increasing specific leaf area (SLA). However, herbivore abundance was not affected by prior frost damage. Two feeding trials using Anoplognathus chloropyrus and Hyalarcta huebneri and a morphometric study of Ctenarytaina eucalypti were conducted to assess the performance of herbivores on trees that had suffered more or less frost damage. Consumption by A. chloropyrus and H. huebneri was unaffected by foliage origin (damaged versus healthy). Hyalarcta huebneri grew faster when fed leaves from previously damaged trees, and C. eucalypti from previously damaged trees were larger than those from healthy trees. Enhanced insect performance on frost damaged plants may have resulted from the high specific leaf area (most likely thinner) leaves. The herbivore abundance data did not support the hypothesis that previously frost damaged plants are preferred by insects. However, increased growth of H. huebneri and larger body size of C. eucalypti on damaged trees indicates that previously stressed trees may produce leaves of higher nutritional value.