Suchergebnisse

European corn borer (Ostrinia nubilalis) (ECB) is an important maize pest in central and northern Europe. Presently it is controlled by insecticides or biological agents such as Trichogramma brassicae in several European countries, excluding Slovenia, where the pest's pressure is highly variable and no appropriate mechanization is available. Lessening the dependence on chemical pesticides is an integral part of the European Union's agenda for agriculture. Mass release of Trichogramma spp. could be seen as a promising alternative for ECB control in countries with a highly fluctuating ECB pressure and no mechanization for insecticide applications. However, no records of naturally occurring hymenopteran parasitoids of ECB exist in Slovenia. To address this important under-researched topic and provide the expert basis for potential introduction of ECB egg parasitoids in Slovene maize production, a systematic inventarisation programme of ECB parasitoids was launched in 2010. Additionally, ECB flight was monitored in 2011 and 2012 at two locations in Slovenia: Jablje and Rakičan. In both locations two ECB generations were observed. ECB was fist observed at the end of May in Rakičan. During the five years of the systematic survey we discovered two ECB parasitoid species. ECB egg masses were parasitized by Trichogramma brassicae, whereas ECB pupae were parasitized by Tycherus nigridens, with 6 or 7 % parasitation rate, respectively. T. nigridens represents a new taxon report for Slovenia. We conclude that there is a strong need for undertaking systematic surveys of natural enemies of agricultural pests.

6 Pags., 5 Tabls. ; The most important pest of maize (Zen mays L.) in North America and Europe is the European corn borer (Ostrinia nubilalis Hbn). However, in southern Europe another corn borer species, the pink stem borer (Sesamia nonagrioides Lef.), also causes significant damage to maize. The damage caused by the pink stem borer in the northwest of Spain was not important a few years ago, but today this damage has increased considerably. Few studies about this pest have been made thus far. The first objective of this work was to study the population quantify and seasonal appearance of Sesamia nonagrioides in this area. Two trials were carried out in two years under natural field conditions with different sowing dates, thus covering the damage at different stages where the plant-insect relationship could change. The results showed that the attacks varied in intensity depending on the year and sowing date. Early sowing could be a good method for cultural control of Sesamia nonagrioides because the material is too mature and escaped borer attack. Although cultural control could be effective in preventing or reducing the damage, genetic resistance is another alternative that could be used alone or joined with other control components for integrated pest management. The first step in this insect-resistance breeding program is to identify sources of resistance. Consequently, the second objective was to study the resistance/tolerance of twenty maize inbred lines under artificial infestation conditions with Sesamia nonagrioides. The inbred lines were evaluated for resistance and other agronomic traits. Significant differences were found for all traits. The inbred lines were divided according to maturity groups: early and late. Early maturing inbreds had the greatest damage. The early inbreds EP37, W153R and CM105 and the late inbreds Va26 and W64A showed the best resistance to the pest. Thus, they could be promising sources of resistance or tolerance to pink stem borer. These lines may be suitable far use directly in the formation of resistant hybrids and new resistant inbred lines. Further, they and others could be used for the development of resistant synthetics, which could become the base material to obtain resistant varieties to Sesamia nonagrioides. ; This work was supported by the Committee for Science and Technology of Spain (project AGR89-0537) and the Autonomous Government of Galicia (project XUGA40301A90). ; Peer reviewed

The European corn borer Ostrinia nubilalis is a pest species, whose fifth instar larvae gradually develop cold hardiness during diapause. The physiological changes underlying diapause progression and cold hardiness development are still insufficiently understood in insects. Here, we follow a complex of changes related to energy metabolism during cold acclimation (5°C) of diapausing larvae and compare this to warm-acclimated (22°C) and non-diapause controls. Capillary electrophoresis of nucleotides and coenzymes has shown that in gradually cold-acclimated groups concentrations of ATP/ADP and, consequently, energy charge slowly decrease during diapause, while the concentration of AMP increases, especially in the first months of diapause. Also, the activity of cytochrome c oxidase (COX), as well as the concentrations of NAD+ and GMP, decline in cold-acclimated groups, until the latter part of diapause, when they recover. Relative expression of NADH dehydrogenase (nd1), coenzyme Q-cytochrome c reductase (uqcr), COX, ATP synthase (atp), ADP/ATP translocase (ant), and prohibitin 2 (phb2) is supressed in cold-acclimated larvae during the first months of diapause and gradually increases toward the termination of diapause. Contrary to this, NADP+ and UMP levels significantly increased in the first few months of diapause, after gradual cold acclimation, which is in connection with the biosynthesis of cryoprotective molecules, as well as regeneration of small antioxidants. Our findings evidence the existence of a cold-induced energy-saving program that facilitates long-term maintenance of larval diapause, as well as gradual development of cold hardiness. In contrast, warm acclimation induced faster depletion of ATP, ADP, UMP, NAD+, and NADP+, as well as higher activity of COX and generally higher expression of all energy-related genes in comparison to cold-acclimated larvae. Moreover, such unusually high metabolic activity, driven by high temperatures, lead to premature mortality in the warm-acclimated group after 2 months ...

The European corn borer Ostrinia nubilalis is a pest species, whose fifth instar larvae gradually develop cold hardiness during diapause. The physiological changes underlying diapause progression and cold hardiness development are still insufficiently understood in insects. Here, we follow a complex of changes related to energy metabolism during cold acclimation (5°C) of diapausing larvae and compare this to warm-acclimated (22°C) and non-diapause controls. Capillary electrophoresis of nucleotides and coenzymes has shown that in gradually cold-acclimated groups concentrations of ATP/ADP and, consequently, energy charge slowly decrease during diapause, while the concentration of AMP increases, especially in the first months of diapause. Also, the activity of cytochrome c oxidase (COX), as well as the concentrations of NAD(+) and GMP, decline in cold-acclimated groups, until the latter part of diapause, when they recover. Relative expression of NADH dehydrogenase (nd1), coenzyme Q-cytochrome c reductase (uqcr), COX, ATP synthase (atp), ADP/ATP translocase (ant), and prohibitin 2 (phb2) is supressed in cold-acclimated larvae during the first months of diapause and gradually increases toward the termination of diapause. Contrary to this, NADP(+) and UMP levels significantly increased in the first few months of diapause, after gradual cold acclimation, which is in connection with the biosynthesis of cryoprotective molecules, as well as regeneration of small antioxidants. Our findings evidence the existence of a cold-induced energy-saving program that facilitates long-term maintenance of larval diapause, as well as gradual development of cold hardiness. In contrast, warm acclimation induced faster depletion of ATP, ADP, UMP, NAD(+), and NADP(+), as well as higher activity of COX and generally higher expression of all energy-related genes in comparison to cold-acclimated larvae. Moreover, such unusually high metabolic activity, driven by high temperatures, lead to premature mortality in the warm-acclimated group after ...

The European corn borer Ostrinia nubilalis is a pest species, whose fifth instar larvae gradually develop cold hardiness during diapause. The physiological changes underlying diapause progression and cold hardiness development are still insufficiently understood in insects. Here, we follow a complex of changes related to energy metabolism during cold acclimation (5°C) of diapausing larvae and compare this to warm-acclimated (22°C) and non-diapause controls. Capillary electrophoresis of nucleotides and coenzymes has shown that in gradually cold-acclimated groups concentrations of ATP/ADP and, consequently, energy charge slowly decrease during diapause, while the concentration of AMP increases, especially in the first months of diapause. Also, the activity of cytochrome c oxidase (COX), as well as the concentrations of NAD + and GMP, decline in cold-acclimated groups, until the latter part of diapause, when they recover. Relative expression of NADH dehydrogenase ( nd1 ), coenzyme Q-cytochrome c reductase ( uqcr ), COX, ATP synthase ( atp ), ADP/ATP translocase ( ant ), and prohibitin 2 ( phb2 ) is supressed in cold-acclimated larvae during the first months of diapause and gradually increases toward the termination of diapause. Contrary to this, NADP + and UMP levels significantly increased in the first few months of diapause, after gradual cold acclimation, which is in connection with the biosynthesis of cryoprotective molecules, as well as regeneration of small antioxidants. Our findings evidence the existence of a cold-induced energy-saving program that facilitates long-term maintenance of larval diapause, as well as gradual development of cold hardiness. In contrast, warm acclimation induced faster depletion of ATP, ADP, UMP, NAD + , and NADP + , as well as higher activity of COX and generally higher expression of all energy-related genes in comparison to cold-acclimated larvae. Moreover, such unusually high metabolic activity, driven by high temperatures, lead to premature mortality in the warm-acclimated group after 2 months of diapause. Thus, our findings strongly support the importance of low temperature exposure in early diapause for gradual cold hardiness acquisition, successful maintenance of the resting state and return to active development. Moreover, they demonstrate potentially adverse effects of global climate changes and subsequent increase in winter temperatures on cold-adapted terrestrial organisms in temperate and subpolar regions.

Farmers who plant Bacillus thuringiensis (Bt) corn are obligated to plant a 20% non-Bt corn refuge as part of an Insect Resistance Management program. This paper analyzes the economics of alternative refuge configurations. Ignoring potential genetically modified organism (GMO) separation requirements, planting strips is the least cost method of meeting the 20% refuge requirement. ; Includes bibliographical references

The definitive version is available at: http://www.sciencedirect.com/science/journal/02612194 ; In Europe, corn borer attack is the main biotic stressor for the maize (Zea mays L.) crop. European corn borer (Ostrinia nubilalis Hbn.) is the most important maize pest in central and north Europe, while pink stem borer (Sesamia nonagrioides Lef.) is predominant in warmer areas of southern Europe. The objective of this study was the evaluation of the European Maize Union Landrace Core Collection (EUMLCC) for yield under infestation with European corn borer (O. nubilalis) and pink stem borer (S. nonagrioides). Eighty-five landraces from Germany, Spain, France, Greece, Italy, and Portugal were evaluated, under corn borer infestation, for yield, grain moisture, and days to flowering at two locations in Spain. Landraces were evaluated separately in four trials that corresponded to four maturity groups. In each maturity group, there were significant differences among landraces for yield of infested plants. Extra-early landraces, ESP0090214, FRA0410010, and ESP0070339; early landraces, FRA0410022, and ESP11985022; midseason landraces, PRT00100392 and ESP11981047; and late landraces, PRT00100569 and PRT00100530, were promising sources of high-yielding maize under corn borer infestation and showed relative earliness within their maturity groups. ; Research supported by the European Union (RESGEN-CT96-088) and the Excma. Diputación Provincial de Pontevedra, Spain. A. Butrón and G. Padilla acknowledge the support that they got from the Spanish Ministry for Science and Technology and the 'Cabildo de la Isla de La Palma', respectively. ; Peer reviewed

7 Pags., 9 Tabls. ; The European corn borer (Ostrinia nubilalis Hbn) is an important insect pest of maize (Zea mays L.) in Europe. However, the larvae of pink stem borer (Sesamia nonagrioides Lef.) produce important damage to the stems, especially in Southern Europe. The first step in an insect-resistance breeding program is to identify sources of resistance. The objective of this work was to study the resistance/tolerance of several populations of maize to attack by corn borers in general, and of Sesamia nonagrioides in particular. Twenty landraces of maize were evaluated for two years at two locations under natural infestation. In one location most of the larvae that were found belonged to Sesamia while in the other location the larvae of Ostrinia were more abundant. Agronomic and resistant traits were analyzed in all trials and the best varieties for resistance. along with new material, were evaluated further under artificial infestation conditions with Sesamia nonagrioides. The extraearly and early material suffered less borer damage than the late and midseason material, because the early populations probably escaped the second brood of borers. Moreover, the varieties with small proportion of damaged stems come from the Ebro valley. The germplasm of this area. then, could be a good source of resistance or tolerance to the borers. However, it showed a low yield. The EPS7(S)C2 synthetic also had good resistance under artificial infestations with Sesamia nonagrioides. Further, it showed better yield than the landraces because two cycles of S1 recurrent selection for yield have been carried out in this synthetic. Therefore EPS7(S)C2 could be the base material in a breeding program to obtain resistant varieties to the pink stem borer. ; This workk was supportcd by the Commitee for Science and Technology (Comisión Inteministerial de Ciencia y Tecnología) of Spain (projecl AGR89-0537) and the Department of Education of the Autonomous Government of Galicia (project XU-GA40301A90). ; Peer reviewed

The European corn borer (Ostrinia nubilalis Hbn) is an important insect pest of maize (Zea mays L.) in Europe. However, the larvae of pink stem borer (Sesamia nonagrioides Lef.) produce important damage to the stems, especially in Southern Europe. The first step in an insect-resistance breeding program is to identify sources of resistance. The objective of this work was to study the resistance/tolerance of several populations of maize to attack by corn borers in general, and of Sesamia nonagrioides in particular. Twenty landraces of maize were evaluated for two years at two locations under natural infestation. In one location most of the larvae that were found belonged to Sesamia while in the other location the larvae of Ostrinia were more abundant. Agronomic and resistant traits were analyzed in all trials and the best varieties for resistance. along with new material, were evaluated further under artificial infestation conditions with Sesamia nonagrioides. The extraearly and early material suffered less borer damage than the late and midseason material, because the early populations probably escaped the second brood of borers. Moreover, the varieties with small proportion of damaged stems come from the Ebro valley. The germplasm of this area. then, could be a good source of resistance or tolerance to the borers. However, it showed a low yield. The EPS7(S)C2 synthetic also had good resistance under artificial infestations with Sesamia nonagrioides. Further, it showed better yield than the landraces because two cycles of S1 recurrent selection for yield have been carried out in this synthetic. Therefore EPS7(S)C2 could be the base material in a breeding program to obtain resistant varieties to the pink stem borer. ; This work was supported by the Committee for Science and Technology of Spain (Project AGR89-0537) and the Department of Education of the Autonomous Government of Galicia (Project XUGA40301A90). ; Peer reviewed

The box tree moth (Cydalima perspectalis) origins from East Asia. In Europe, it was recorded for the first time in 2007, and in Poland in 2012. By the end of 2020, it was found all over Poland. There are no published data on the range of C. perspectalis occurrence in Poland because it is not a quarantine pest in the European Union and is not subject to official monitoring. Data collected in 2018–2020 via a website dedicated to monitoring, for the first time, illustrate the current range and its largest concentrations in southern and central Poland. The monitoring confirmed that the main directions of the invasion are related to the main communication routes of Poland (south-north) and are of a long-distance character. The dispersal pattern corresponds to the model developed for Cameraria ohridella: a stratified dispersal model that considers long-distance road/rail transport. The second important factor contributing to the invasion of C. perspectalis are large human communities enabling rapid local dispersion (a diffusion model). Comparing its invasion with the monitoring data from 2007–2013 of two other invasive pests of Poland: Ostrinia nubilalis and Diabrotica virgifera, shows that a diffusion model best describes the spatial spread of these pests only to uninhabited neighboring areas.

The main mycotoxigenic fungi found in maize in the Mediterranean basin include Aspergillus section Flavi and several Fusarium species, Fusarium section Liseola being the more widespread. While Aspergillus section Flavi species can develop in the field or in stored maize in Mediterranean countries, Fusarium species colonise maize ears in the field. As a consequence, fumonisins are the major contaminants in Mediterranean maize, together with aflatoxins. The prevalence of Fusarium section Liseola in the Mediterranean countries is closely linked to the activity of insects such as Sesamia nonagrioides and Ostrinia nubilalis. The incidence of the different mycotoxigenic fungi and mycotoxins across the Mediterranean countries is extensively reviewed in this work. Furthermore, both pre- and postharvest strategies to reduce the presence of such toxins in the maize chain are described. Finally, the incidence and levels of mycotoxins encountered in maize products intended for direct human consumption in the Mediterranean countries are also assessed; they are much lower than those in maize grain as a result of food processing technologies. ; The authors wish to thank to FP7 EU project MycoRed (GA222690) for giving the opportunity to prepare this review article as well as to the Spanish Government (project AGL2010-22182-C04-04) for the financial support.

Correspondance: bourguet@supagro.inra.fr ; National audience ; The use of transgenic crops producing toxins from the bacterium Bacillus thuringiensis – or Bt crops – is associated with the risk that the targeted pests become resistant to these toxins. To reduce this risk, the US government required the implementation of a strategy named High Dose/Refuge (HDR). This strategy is based on maintaining Bt toxin-free plants or crops – referred to as « refuges » – to preserve a pool of susceptible insects in the vicinity of Bt fields. Among other factors, its efficiency relies on a high gene flow between these susceptible individuals and any resistant individuals selected in Bt fields. For several pests targeted by these toxins, this strategy was nevertheless implemented when little was in fact know, as to the life history traits likely to influence the intensity of the gene flow. Part of this gap has been filled since then: we summarize here the recent advances on the European corn borer (ECB), one of the main targets of insecticidal Bt maize. Although this moth pest is highly polyphagous, its other host plants – whether wild or cultivated – do not provide a sufficient source of susceptible individuals to efficiently prevent toxin resistance from developing. Moreover, a fraction of the ECB reproduce in close vicinity of their place of emergence, so that refuges situated a few hundred meters from Bt maize fields – the maximal distance currently required is 800 meters – may not warrant a sufficient intermixing between susceptible and resistant individuals. In crop rotation situations, this intermixing could however be facilitated through a contrasted management of herbaceous maize field borders. Although 10 years after the beginning of Bt maize cultivation no resistance has yet broken out, our data suggests that it is illusory to aim at a universally suitable strategy, and that the HDR strategy – as currently implemented – may not necessarily be optimal ; La culture de plantes transgéniques Bt – produisant des toxines ...

Correspondance: bourguet@supagro.inra.fr ; National audience ; The use of transgenic crops producing toxins from the bacterium Bacillus thuringiensis – or Bt crops – is associated with the risk that the targeted pests become resistant to these toxins. To reduce this risk, the US government required the implementation of a strategy named High Dose/Refuge (HDR). This strategy is based on maintaining Bt toxin-free plants or crops – referred to as « refuges » – to preserve a pool of susceptible insects in the vicinity of Bt fields. Among other factors, its efficiency relies on a high gene flow between these susceptible individuals and any resistant individuals selected in Bt fields. For several pests targeted by these toxins, this strategy was nevertheless implemented when little was in fact know, as to the life history traits likely to influence the intensity of the gene flow. Part of this gap has been filled since then: we summarize here the recent advances on the European corn borer (ECB), one of the main targets of insecticidal Bt maize. Although this moth pest is highly polyphagous, its other host plants – whether wild or cultivated – do not provide a sufficient source of susceptible individuals to efficiently prevent toxin resistance from developing. Moreover, a fraction of the ECB reproduce in close vicinity of their place of emergence, so that refuges situated a few hundred meters from Bt maize fields – the maximal distance currently required is 800 meters – may not warrant a sufficient intermixing between susceptible and resistant individuals. In crop rotation situations, this intermixing could however be facilitated through a contrasted management of herbaceous maize field borders. Although 10 years after the beginning of Bt maize cultivation no resistance has yet broken out, our data suggests that it is illusory to aim at a universally suitable strategy, and that the HDR strategy – as currently implemented – may not necessarily be optimal ; La culture de plantes transgéniques Bt – produisant des toxines ...

Correspondance: bourguet@supagro.inra.fr ; National audience ; The use of transgenic crops producing toxins from the bacterium Bacillus thuringiensis – or Bt crops – is associated with the risk that the targeted pests become resistant to these toxins. To reduce this risk, the US government required the implementation of a strategy named High Dose/Refuge (HDR). This strategy is based on maintaining Bt toxin-free plants or crops – referred to as « refuges » – to preserve a pool of susceptible insects in the vicinity of Bt fields. Among other factors, its efficiency relies on a high gene flow between these susceptible individuals and any resistant individuals selected in Bt fields. For several pests targeted by these toxins, this strategy was nevertheless implemented when little was in fact know, as to the life history traits likely to influence the intensity of the gene flow. Part of this gap has been filled since then: we summarize here the recent advances on the European corn borer (ECB), one of the main targets of insecticidal Bt maize. Although this moth pest is highly polyphagous, its other host plants – whether wild or cultivated – do not provide a sufficient source of susceptible individuals to efficiently prevent toxin resistance from developing. Moreover, a fraction of the ECB reproduce in close vicinity of their place of emergence, so that refuges situated a few hundred meters from Bt maize fields – the maximal distance currently required is 800 meters – may not warrant a sufficient intermixing between susceptible and resistant individuals. In crop rotation situations, this intermixing could however be facilitated through a contrasted management of herbaceous maize field borders. Although 10 years after the beginning of Bt maize cultivation no resistance has yet broken out, our data suggests that it is illusory to aim at a universally suitable strategy, and that the HDR strategy – as currently implemented – may not necessarily be optimal ; La culture de plantes transgéniques Bt – produisant des toxines ...