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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2024

Abstract

BACKGROUND As regulations on pesticides become more stringent, it is likely that there will be interest in steam as an alternative approach for soil disinfestation. This study investigates the feasibility of utilizing a soil steaming device for thermal control of invasive plants. RESULTS Seeds of Echinochloa crus-galli, Impatiens glandulifera, Solidago canadensis, and rhizome fragments of Reynoutria × bohemica were examined for thermal sensitivity through two exposure methods: (1) steam treatment of propagative material in soil; (2) exposure of propagative material to warm soil just after heated by steam. Soil temperatures in the range of 60–99 °C and dwelling period of 3 min were tested. Increased soil temperature decreased seed germination/rhizome sprouting. The exposure method had a significant effect where higher temperatures were needed to reduce the seed germination/rhizome sprouting in method 2 explained by the effect of extra heat given in method 1. Using method 1, for E. crus-galli and S. canadensis, the maximum mean temperature of approximately 80 °C was enough to achieve the effective weed control level (90%). This was lower for I. glandulifera and higher for R. × bohemica. Using method 2, 90% control was achieved at 95 °C for S. canadensis; more than 115 °C for I. glandulifera; and more than 130 °C for E. crus-galli and R. × bohemica. CONCLUSION Our findings showed a promising mortality rate for weeds propagative materials through soil steaming. However, the species showed varying responses to heat and therefore steam regulation should be based on the differences in weeds' susceptibility to heat.

Abstract

The fall armyworm, Spodoptera frugiperda, situation in Africa remains a priority threat despite significant efforts made since the first outbreaks in 2016 to control the pest and thereby reduce yield losses. Field surveys in Benin and Mali reported that approximately one-week post-emergence of maize plants, the presence of fall armyworm (egg/neonates) could be observed in the field. Scouting for fall armyworm eggs and neonates is, however, difficult and time consuming. In this study, we therefore hypothesized that the optimum timeframe for the fall armyworm female arriving to lay eggs in sown maize fields could be predicted. We did this by back-calculating from interval censored data of egg and neonates collected in emerging maize seedlings at young leaf developmental stage. Early time of ovipositing fall armyworm after sowing was recorded in field experiments. By using temperature-based models to predict phenological development for maize and fall armyworm, combined with analytical approaches for time-to-event data with censored status, we estimated that about 210 accumulated Degree Days (DD) is needed for early detection of neonate larvae in the field. This work is meant to provide new insights on timely pest detection and to guide for precise timing of control measures.

To document

Abstract

Six species of Ips de Geer (Coleoptera: Curculionidae; Scolytinae) occur in Europe. They attack weakened or dead conifers but may become aggressive and mass-attack living trees. All species have expanded their ranges in Europe since the late 19th century. Here, we analyse the patterns of this spread and discuss the factors at play. Starting with an assessment of distribution changes of the insects and of their host trees since the nineteenth century, we describe how and, when known, why territorial changes occurred in Fennoscandia (Norway, Sweden, Denmark, and Finland), Central Europe (Czechia, Slovakia, Hungary, Poland, Austria, Germany), the Netherlands, Belgium and Great Britain. Based on these country narratives, we discuss the conditions for, and causes of, territorial expansion. A necessary condition is the presence of host trees of vulnerable ages and sizes, resulting from the post-glaciation expansion of host range. Population changes and territorial expansion are influenced by environmental or anthropic drivers: climatic events (droughts and storms), silvicultural practices and trade. Three main factors favour or hamper the response of the different species to these drivers: active and passive flight capacity, dispersal upon emergence and response to pheromones after take-off, and pre-dispersal mating. These criteria enable identification of differences in the invasive capacities of the six species. In particular, Ips typographus appears to be a poor invader worldwide because of its wide dispersal upon emergence and its delayed response to pheromones. Finally, we discuss the risks to the Irish forests so far uncolonised by Ips species.