Grape phylloxera (Daktulosphaira vitifoliae) can infest both roots and leaves of Vitis species. In commercial vineyards planted with Vitis vinifera scions grafted on rootstocks, grape phylloxera infestation is generally limited to root feeding. Vineyards are, however, increasingly subjected to vineyard-wide foliar infestations that last throughout the growing season. While some vineyards are affected by the infestation pressure of external leaf-feeding populations, other annually affected V. vinifera vineyards do not have these in their vicinity. Much is known about the damage potential of grape phylloxera root feeding; however, data on how phylloxera leaf infestation affects V. vinifera grapevines in commercial vineyards are lacking. This study, therefore, aimed to assess whether grapevine growth and yield are affected due to leaf infestation as it occurred in three commercial vineyards in the study area. Treatments were based on phylloxera leaf infestation and additional defoliation. Single-leaf carbon acquisition was measured with gas exchange analyses on healthy and galled leaves. Pruning weight and internode length were measured to assess the effect of leaf infestation and the effect of plant growth and vigour on leaf gall outbreaks. Yield quantity and quality were measured, and grapes were vinified for sensory analyses. Furthermore, using enzymatic analyses, non-structural carbohydrates were analysed in perennial wood. A significant decrease in sugar content in grapes (10 %) and starch reserves in perennial wood (11 %) was found in the most heavily infested vineyard. Grape must of infested plants in another vineyard furthermore showed a significantly higher level of titratable acid (7.5 %). Significant infestation effects seen in one vineyard were not significant in the other two vineyards. No significant differences were seen for carbon acquisition, harvest quantity, wine sensory analysis, pruning weight or internode length. The overall effect of phylloxera leaf infestation in the studied vineyards was, therefore, marginal. Grapevine vigour did not differ between infested vines, insecticide-sprayed vines, and vines on which no leaf infestation outbreaks took place. By analysing phylloxera leaf infestation under field conditions, these preliminary results form a basis for future long-term field studies about phylloxera leaf feeding on Vitis vinifera within the context of other biotic and abiotic plant stresses.

Depending on their life cycle, grape phylloxera (Daktulosphaira vitifoliae Fitch) leaf-feeding populations are initiated through asexually produced offspring or sexual recombination. The vine’s initial foliar larvae may originate from root-feeding phylloxera or wind-drifted foliar larvae from other habitats. Though some studies have reported phylloxera leaf-feeding in commercial vineyards, it is still unclear if they are genetically distinct from the population structure of these two sources. Using seven SSR-markers, this study analyzed the genetic structure of phylloxera populations in commercial vineyards with different natural infestation scenarios and that of single-plant insect systems that exclude infestation by wind-drifted larvae. We saw that during the vegetation period, phylloxera populations predominately go through their asexual life cycle to migrate from roots to leaves. We provided evidence that such migrations do not exclusively occur through wind-drifted foliar populations from rootstock vines in abandoned thickets, but that root populations within commercial vineyards also migrate to establish V. vinifera leaf populations. Whereas the former scenario generates foliar populations with high genotypic diversity, the latter produces population bottlenecks through founder effects or phylloxera biotype selection pressure. We finally compared these population structures with those of populations in their native habitat in North America, using four microsatellite markers.

The cuticle-covered surface forms the interface between plant parts, including fruits, and their environment. The physical and chemical properties of fruit surfaces profoundly influence plant-frugivore interactions by shaping the susceptibility and suitability of the host for the attacker. Grapevine ( Vitis vinifera , Vitaceae) serves as one of the various host plants of the spotted wing drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), which is invasive in several parts of the world and can cause major crop losses. The susceptibility of wine towards this pest species differs widely among varieties. The objective of our study was to identify physical and chemical traits of the berry surface that may explain the differences in susceptibility of five grape varieties to D. suzukii . Both preferences of adult D. suzukii and offspring performance on intact versus dewaxed (epicuticular wax layer mechanically removed) grape berries were investigated in dual-choice assays. Moreover, the morphology and chemical composition of cuticular waxes and cutin of the different varieties were analyzed. Bioassays revealed that the epicuticular wax layer of most tested grape varieties influenced the preference behavior of adult flies; even less susceptible varieties became more susceptible after removal of these waxes. In contrast, neither offspring performance nor berry skin firmness were affected by the epicuticular wax layer. The wax morphology and the composition of both epi- and intracuticular waxes differed pronouncedly, especially between more and less susceptible varieties, while cutin was dominated by ω-OH-9/10-epoxy-C18 acid and the amount was comparable among varieties within sampling time. Our results highlight the underestimated role of the epicuticular surface and cuticle integrity in grape susceptibility to D. suzukii.

The multiple land use of agricultural areas is a building block for increased land use efficiency. Unlike monoculture, integrated crop–livestock systems optimally improve ecosystem services, making it an important field of research and application for adapting land use and food systems that have sustainability deficits. The integration of sheep in viticulture production is described as a promising example of an integrated crop–livestock system. While some studies of the integration of sheep into vineyards are already available for other parts of the world, there is still no research on its implementation in Central European viticulture systems. In order to fill this gap of knowledge, we conducted standardized interviews with 34 winegrowers who already graze sheep in their vineyards. The method allowed a wider overview of the implementation of the integrated crop-livestock system than would have been possible with other approaches. Furthermore, the authors kept sheep in their own vineyard for three years to evaluate the statements of the survey participants. The period during which sheep graze in vineyards is quite heterogeneous in Central Europe. Some farms use sheep only during vine dormancy; others also let sheep graze during a certain period in summer. There are also viticulture training systems where grazing is almost continuously possible. In Central Europe, summer grazing normally requires operational adjustments such as lifting the wires of the training system and branches of the vine; otherwise, the vines could be damaged. This option seems to be tailored to the training system in use. Some interviewees mentioned that sheep not only use the accompanying vegetation as fodder and therefore control the undervine growth, but in some cases, they were also able to replace other work processes, such as defoliating the grape zone or cleaning undesired vine shoots near the ground. However, a high additional workload due to livestock keeping was also mentioned by some survey participants. Some of the interviewees cooperate with shepherds, which could help to solve this challenge. Finally, we summarize possible opportunities and risks of this integrated crop–livestock system. Integrating sheep in vineyards seems to be quite feasible in the period of vine dormancy, whereas more information and considerably more effort is needed to integrate sheep during the vegetation period. Further research is needed to answer open questions especially for the necessary adaptions of the common vine training system or the implementation of alternative systems more suitable to combine with livestock keeping. Some practitioners found opportunities to merchandize the use of sheep in wine sales. This potentially unique selling point could be a solution for a broader consideration of sheep in vineyards.

Grape phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera: Phylloxeridae), is a destructive pest for global viticulture. With the grafting of the susceptible cultivated grapevine (Vitis vinifera L., Vitaceae) on top of tolerant Vitis spp. rootstock, root infestation no longer causes vine death. These tolerant rootstock vines are hybrids of American species that are often highly susceptible to leaf infestation. Though leaf infestation is normally rarely seen on V. vinifera, some commercial vineyards have been showing high intensities of leaf galls for many years. In this study, two possible factors are investigated to explain these anomalies: (1) intra-specific differences in phylloxera host plant specialization, and (2) improved environmental settings for infestation due to temperature increase. To study the former, a phylloxera biotyping assay was conducted after whole-plant (both root and leaf) infestations, and for the latter, a temperature increase simulation was performed with potted plants in climate chambers. Both assays also contained a phylloxera control biotype C, obtained from an American rootstock hybrid (Vitis berlandieri Planch. x Vitis riparia Michx.). The biotyping assay showed that field-sampled populations from V. vinifera leaf galls had innate advantages to infest the leaves of this host plant species compared to those of the American rootstock hybrid. This is therefore the first study to categorize a phylloxera population as biotype G, using controlled experimental conditions with biological pest control. At moderate temperatures (22 degrees C), infestation was similar as in the biotyping assay, but at higher temperatures (27 degrees C), biotype G seems to lose its comparative advantage to infest V. vinifera leaves. Specifically, at higher temperatures, insect performance in terms of leaf gall intensity, development, and egg-laying of both biotype G and C is improved on American rootstock hybrids and worsened on V. vinifera compared to infestations at moderate temperatures. We discuss possible explanations for these findings and how these experimental results may be extrapolated to field settings.

Understanding the dynamics of pest insect populations in relation to the presence of non‐crop habitats and infestation levels of adjacent crops is essential to develop sustainable pest management strategies. The invasive pest species Drosophila suzukii (Diptera: Drosophilidae) is able to utilize a broad range of host plants. In viticulture, scientific risk assessment for D. suzukii has only recently started and studies assessing the effects of field margins containing wild host plants on D. suzukii population dynamics and on infestation risks in adjacent vineyards are lacking. Thus, in a one‐year field study, the role of different field margins on fly abundance and crop infestation in adjacent vineyards of Vitis vinifera, variety “Pinot Noir,” were investigated. Different monitoring methods were conducted to assess fly distribution, sex ratio and grape infestation in 14 vineyards adjacent to field margins containing either blackberry (BB) Rubus spp. or non‐host (NH) plants. Our results show that blackberries strongly enhanced D. suzukii abundance within field margin vegetation all year long, whereas fly abundance in vineyards adjacent to BB margins was just enhanced in some seasonal periods. Moreover, the influence of BB margins was limited by distance. However, high fly numbers in BB field margins did result in zero egg infestation of “Pinot Noir” berries. These results may have important implications for winegrowers to make efficient management decisions: regardless of high abundance of adult D. suzukii, only grape berry monitoring can assess the actual infestation risk and the potential need to take management action.

Drosophila suzukii is an invasive fruit pest and represents a potential economic threat to viticulture. After first observations of D. suzukii in Europe in 2008, research mainly focused on the evaluation of the host range and infestation risk for fruit and berry crops. However, the risk assessment of D. suzukii in viticulture has only recently started. Understanding the factors influencing preferences of D. suzukii for host species and varieties as well as offspring performance is essential to improve management strategies. We investigated the field infestation of different grape varieties across Baden-Wuerttemberg, southwestern Germany, between 2015 and 2018. Moreover, we performed dual-choice assays in the laboratory to investigate whether adults show preferences for certain varieties and whether offspring performance differs between varieties. Furthermore, we studied the impact of grape damage on choice behavior. Field monitoring revealed that D. suzukii show preferences for red varieties, whereas almost no oviposition occurred in white varieties. The results of dual-choice assays confirmed that D. suzukii preference and performance are influenced by grape variety and that flies preferred damaged over intact "Pinot Noir", "Pinot Blanc", and "Müller-Thurgau" berries. Overall, these findings may have important implications for winegrowers regarding cultivated varieties, grape health, and insecticide reduction.

Bois noir' is a phytoplasma-mediated grapevine yellows disease that causes great economic damage in European vineyards. Previous studies have examined habitat relationships on a regional scale, which help to better understand the large-scale epidemiology. Local drivers, such as micro-habitat preferences of the vector (Hyalesthes obsoletus, a cixiid planthopper), or local interactions with reservoir host plants, however, are still poorly understood, although this knowledge is crucial for developing site-specific management strategies.Here, we examined the local environment-species relationships of a phytoplasma-mediated grapevine disease on a scale of 15m in a 2.9 ha vineyard using: (i) data on elevation and habitat types; (ii) cover of host plants Urtica dioica and Convolvulus arvensis over three seasons, (iii) vector monitoring over four seasons; (iv) genetic tests for phytoplasma presence in the vector; and (v) inspection of 6056 grapevine plants for visual symptoms of the 'bois noir' disease. The data were analyzed in a joint causal model that describes the interplay between vector, pathogen, disease and environment, estimated with Bayesian inference.Our results indicate that surrounding natural and semi-natural vegetation (fallow land, forest and managed agricultural land) and high density of the major host plant U. dioica are associated with an increase in vector population densities. Higher vector population densities at low availability of U. dioica were associated with higher phytoplasma infection rates in the vector. The prevalence of disease symptoms in grapevine plants was nonetheless more affected by grapevine cultivar and higher elevation than by the estimated availability of infected vectors.The results of our local analysis support current bois noir management recommendations stating that (1) removal of the host plant U. dioica should be best carried out in either spring or autumn; and (2) grapevine cultivars are unequally susceptible. Moreover, we provide evidence that U. dioica control before the flight period may result in low U. dioica densities and high H. obsoletus population densities, causing an increase in vector infection rates and disease pressure. (C) 2016 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

Insect-vectored plant diseases often create complex epidemiological systems that are challenging to understand, predict, and manage. An example is 'bois noir' (BN), a phytoplasma-associated grapevine disease commonly found in European vineyards. Although BN has the potential to cause substantial economic damage, the factors that contribute to BN prevalence in vineyards are still not well understood.We used Bayesian inference with generalized linear mixed-effect models to test the hypotheses that (1) grapevine varieties exhibit different BN susceptibility; (2) environment drivers influence prevalence of the disease and occurrence of the vector; and (3) the presence of the main vector is a major determinant of BN occurrence.We found that the presence of the vector Hyalesthes obsoletus increased with increasing isothermality, minimum temperatures during the coldest period, soil erosion, and natural vegetation in close proximity to the vineyards. Presence of the BN disease increased with presence of the vector as well as increasing altitudes and mean annual temperatures. After accounting for those factors, Chardonnay and Riesling showed higher disease prevalence than Muller-Thurgau, Silvaner, and Merlot. Although the vector had an overall positive effect on the disease prevalence, disease and vector occurrence show distinct spatial patterns.In conclusion, our analysis suggests that vector presence is not the only, and maybe not the most important factor for BN disease prevalence. Environment and grape cultivar also play important roles. Hence, area-wide predictions of both environmental disease risk and vector presence, together with information about the susceptibility of grape cultivars, will enable a more targeted disease management. Our modelling framework could easily be applied to other diseases of concern, such as apple proliferation or flavescence doree.

Species distribution models (SDMs), which are well established in many fields of biological research, are still uncommon in the agricultural risk analysis of pest insects. To exemplify the use of SDMs, we investigated the influence of environmental factors on the occurrence of Hyalesthes obsoletus Signoret (Hemiptera: Cixiidae). The planthopper is the only known vector of the grapevine yellows disease 'bois noir'. The study was conducted in 145 locations in the Baden region of southwest Germany. The planthopper was surveyed on host plant patches, consisting of stinging nettle and/or bindweeds. We used a stratified modelling framework where (1) species presence-absence data were related to an extensive environmental dataset using logistic regressions; and (2) different types of average models were developed based on an information theoretic method. The results show that the incidence of H. obsoletus is associated to above-as well as below-ground environmental factors, particularly to the amount of fine soil and average annual precipitation. This result was consistent across all average models. The relative importance of other environmental variables was dependent upon the average model under consideration and thus may vary according to their intended use, either the explanation of habitat requirements or the prediction and mapping of occurrence risks. The study showed that SDMs offer a quantification of species' habitat requirements and thus, could represent a valuable tool for pest management purposes. By providing examples of current issues of grapevine pests in viticulture, we discuss the use of SDMs in agricultural risk analysis and highlight their advantages and caveats.

The haemolymph titre of the phase-related 6-kDa peptide is determined in fourth- and fifth-instar larvae, as well as in adults, by high-performance liquid chromatography. In larvae, the concentration of this peptide slowly increases towards the end of the instar to reach a maximum just before the moult. The titre is slightly higher in the fifth instar than in the fourth instar. In adults, it reaches an average concentration of 0.8 mu g mu L-1 of the haemolymph. In females, a peak is found at day 15 whereas, in males, there are two peaks, the first at day 9 and the second at day 15 after fledging. The role of the peptide in inducing yellow protein mRNA synthesis is investigated, as is its effect on the production of the pheromonal compound phenylacetonitrile (PAN). The peptide stimulates yellow protein mRNA synthesis, but its injection causes no change in yellow colouration. No effect on PAN production is found.

Abstract Solitary and gregarious locusts differ in many traits, such as body color, morphometrics and behavior. With respect to behavior, solitary animals shun each other, while gregarious animals seek each other's company, hence their crowding behavior. General activity, depending on the temperature, occurs throughout the day but is much lower in solitary locusts. Solitary locusts occasionally fly by night while gregarious locusts fly regularly during daytime (swarming). In search of new assays to identify substances that control or modify aspects of (phase) behavior, we designed a simple activity assay, meant to complement existing behavioral measurement tools. The general activity is reflected in the number of wall hits, that is, the number of contacts between the locust and the vertical walls of a small arena. Using this single parameter we were able to quantify differences in total activity of both nymphs and adults of isolation‐reared (solitary), regrouped‐ and crowd‐reared (gregarious) locusts under different conditions. Furthermore, we demonstrate that there are inter‐ and intra‐phase dependent differences in activities of 5th instar nymphs after injections of the three different adipokinetic hormones.

Short peptides can be expressed in plants using synthetic genes encoding multiple copies of the peptide spaced by dibasic endoproteolytic cleavage sites. A synthetic gene encoding an array of repeated copies of proctolin, a very well characterized insect myotropic peptide, spaced by Arg residues, was synthesized and expressed in tobacco plants. The successful production of bioactive proctolin from the precursor in transgenic plants was demonstrated by immunoblot, HPLC, mass spectrometry and a bioassay based on the contraction of isolated cockroach hindgut. These results suggest that in planta, as in animals and yeasts, endopeptidases of the serine proteases family may be involved in precursor processing.

The biological activity of synthetic (Z,Z)-11,13-hexadecadienyl ace- tate, the major pheromone component found in female gland extracts of the oak processionary moth Thaumetopoea processionea, was evaluated in field trials. Traps baited with 10 mg of the chemical efficiently attracted a large number of males provided they were placed in the upper crown region of the oaks. Devices positioned 10–15 m high in the trees attracted significantly more males than those traps installed at 2 or 6–8 m above the ground. Pherocon traps were slightly more efficient than Delta traps, and lower or higher amounts of the attractant in the baits did not significantly influence the number of moths caught. The importance of the stereomeric purity of the lure and the easy isomerization of the (Z,Z)-acetate to other isomers, particularly to the E,E isomer, should be considered for the development of efficient formulations in the field.

The present article summarizes some recent findings relating to the underlying mechanism of phase transition in locusts, from the nonswarming solitarious phase to the swarming gregarious phase. These phases differ in many traits, such as colouration, morphometrics and behaviour. The most comprehensive theory at present to explain the switch from the nonswarming to the swarming form is that the locusts are brought together by the heterogeneity of the environment. They gather at preferential structures and food plants and physical contact then stimulates individuals to gregarize. Phase change can also be transferred across generations by maternal pheromones. The endocrine regulation of phase polymorphism is still not fully understood. The role of ecdysteroids has been studied, so far with no final conclusion. It is remarkable that the prothoracic glands persist longer in isolated-reared adults, which implies that these glands continue to play a role, although they no longer release important amounts of ecdysteroids. Juvenile Hormone, without any doubt, induces certain solitarious characteristics, such as green colouration, but is not the primary causal factor. A real breakthrough was the discovery of [His(7)]-corazonin, made possible by using a novel assay system, the Okinawa albino mutant of Locusta migratoria , which was known to be deficient in this hormone. This peptide, which is produced in the brain and is most likely released via the corpora cardiaca, promotes the gregarious black pigmentation. It also plays a role in morphometrical phase change as well as in behavioural alterations. Corazonin is apparently quite an important peptide not only in locusts, but also in insects in general.

Acidic methanolic extracts of haemolymph, cuticle and eyes of larvae and adults of the migratory locust, Locusta migratoria migratorioides (R. et L.), were subjected to thin layer chromatography. The Rf-values as well as the fluorescent colour of the spots under ultraviolet illumination at 350 nm, were compared to those of 12 pteridine standards. Most of the standards showed a major spot, as well as up to 3 additional minor spots, probably due to the presence of isomers and degradation products. The extract of the haemolymph of untreated larvae and adults yielded 6 different spots. Cuticle and eyes had their own specific pattern. Application of methoprene (analogue of juvenile hormone) induced solitary phase-like pigmentation of the cuticle and green-coloured haemolyph. The content of pterin, biopterin, leucopterin, isoxanthopterin, and probably also of lumazin, increased. The melanization of the cuticle nearly completely disappeared. Similar, but weak effects were observed in neem-oil treated locusts. Application of precocene caused a number of changes in the pigment pattern of all extracts. It also induced some melanization of the cuticle in particular in larvae. Many pigment spots were observed which did not correspond to any of the 12 standard pteridines. The classical concept about the pigment composition of locust haemolymph, namely that it is restricted to melanin, carotenes and biliverdin, needs modification.

Studies on the insecticidal action of plant material of Melia azedarach were done. In a first experiment the active compounds of a crude methanol extract of leaves originating from Greece were enriched by liquid-liquid extraction. The crude extract was washed with petroleum ether and then partitioned between the solvents water and ethyl acetate (EA). A Spodoptera frugiperda bioassay proved that the EA-extract had the highest growth disrupting activity. In a second experiment with S. frugiperda the efficacy of the EA-extract of leaves and fruits originating from Greece was compared. The EC 5 0 -values (effective concentration of extract necessary to reduce larval growth to 50% of the control values) showed that the leaf extract was about 3.8 times more active than the fruit extract. The insecticidal effect of EA-extracts of fruits and leaves originating from Greece and Syria were also compared. Syrian material had higher growth disrupting properties on S. frugiperda than the Greek material. In addition, the EC 5 0 showed that for the concentrations tested, the leaves originating from Syria had the highest activity. The antifeedant effect of fruits originating from Greece on Leucophaea maderae was investigated in a binary choice test. If a high concentration (1%) was added to glass fibre discs, an antifeedant effect was observed. A binary choice test was also used to investigate the antifeedant effect of leaves and fruits originating from Greece and Syria on S. frugiperda. All concentrations (0.01%, 0.1% en 1%) of the extracts had strong effects on the food intake. The Syrian leaves were found to contain the strongest antifeedant. The influence of an EA-extract of Greek leaves on larval development of Neobellieria bullata was also investigated. A concentration of 1000 ppm, added to a liver diet, resulted in a significantly lower number of pupated larvae and lower pupal weight than in the control. In addition, at a concentration of 1000 ppm only 1% of the larvae developed into adult flies, whereas in the control more than 50% of the larvae became adult flies.

During the act of egg laying, in the desert locust Schistocerca gregaria (Forskal 1775), ♀♀ cover their eggs with a substance originating from the accessory glands. It hardens into a foamy material used as a chimney through which the delicate eclosed larvae can climb to the surface. The foam contains an as yet unidentified factor that promotes gregarisation. To distinguish the effect of this factor from that caused by another gregarisation promotory agent, namely the neuropeptide [His 7 ]-corazonin, a comparative developmental study was undertaken. Egg foam significantly influenced the development of both crowd- and isolated-reared hoppers. The development was longer if the eggs were washed and the factor was absent. The morphometrics were only slightly affected, and there was no effect on the coloration of the locusts.

A factor present in the brain and corpus cardiacum responsible for the induction of dark colour in Locusta migratoria was recently isolated and identified from the corpora cardiaca of normally pigmented locusts. The purification of this factor, designated as [His 7 ]-corazonin was monitored using an albino mutant from a laboratory colony of an Okinawa (Japan) strain. In this study, we provide unequivocal mass spectrometric evidence that the brain and the corpora cardiaca of this albino Locusta mutant are deficient in [His 7 ]-corazonin. Previously, [His 7 ]-corazonin was shown to be responsible for the induction of dark body colour patterns as observed in crowded locusts. Using nanoflow-liquid chromatography-mass spectrometry, we demonstrated that this dark colour–inducing hormone is, however, present in the corpora cardiaca of solitary locusts ( Schistocerca gregaria ). Arch. Insect Biochem. Physiol. 47:150–160, 2001. © 2001 Wiley-Liss, Inc.