Hopp til hovedinnholdet

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.

2019

To document

Abstract

This is a post-peer-review, pre-copyedit version of an article published in [Biological Invasions] Locked until 3.8.2020 due to copyright restrictions. The final authenticated version is available online at: https://doi.org/10.1007/s10530-019-02058-x

To document

Abstract

Pandora neoaphidis and Entomophthora planchoniana are widespread and important specialist fungal pathogens of aphids in cereals (Sitobion avenae and Rhopalosiphum padi). The two aphid species share these pathogens and we compare factors influencing susceptibility and resistance. Among factors that may influence susceptibility and resistance are aphid behavior, conspecific versus heterospecific host, aphid morph, life cycle, and presence of protective endosymbionts. It seems that the conspecific host is more susceptible (less resistant) than the heterospecific host, and alates are more susceptible than apterae. We conceptualize the findings in a diagram showing possible transmission in field situations and we pinpoint where there are knowledge gaps.

Abstract

In the family Orchidaceae, many species have highly specialised floral structures and floral fragrances resulting from interactions with specific pollinators. Olfactory cues are important for the moths to locate orchids at a distance, whereas visual cues are important at a closer range. In this study, we combined a portable air entrainment kit with an automated video monitoring system for collecting volatiles and observing behaviour directly around-the-clock (24 h) in the natural habitat of our target plant–arthropod system, the orchid Platanthera chlorantha and the hawkmoth Sphinx pinastri. We found that P. chlorantha was visited almost exclusively by S. pinastri. All the visits occurred after sunset, principally between sunset and midnight. Soon after midnight, visits dropped to levels recorded at sunset, then declined further towards sunrise. The period with most visits matched the peak production of the terpenoids (Z)-β-ocimene and (E)-β-ocimene. In contrast, linalool, (E)-cinnamyl alcohol and benzyl benzoate emission continued to increase beyond the period of peak visits up to sunrise. Methyl benzoate emissions declined throughout the night from a sunset peak. As temporal emission of the two volatile ocimenes from P. chlorantha flowers matches S. pinastri foraging visits to the flowers, we propose that they play a vital role in assisting hawkmoths locate their hosts. This is the first study to show correspondence in the timing of specific scent emissions in orchids and moth activity on the scale of hours.

Abstract

Although supporting high productivity, modern agriculture caused a long-term impact on natural trophic interactions, releasing pests from pressure linked with their natural enemies. Studies have demonstrated that volatiles released under herbivory can recruit natural enemies of pests from a distance. Here, we used a novel biodegradable formulation loaded with induced and food-signalling volatiles with the aim to attract the green lacewing, Chrysoperla carnea, and increase biological control of two cereal aphids Sitobion avenae and Rhopalosiphum padi. The new product consisted of a biodegradable matrix loaded with a 3-component blend of methyl salicylate, acetic acid and phenylacetaldehyde in a 1:1:1 ratio. Field experiments were carried out in a barley field in Norway. Single plants were provided with a 1 ml dollop of the new formulation or with a standard polyethylene emballage dispenser loaded with the same amount of compounds. The number of lacewing eggs and larvae as well as the attraction of additional natural enemies was recorded both on the treated and surrounding plants by visual inspection. At the same time, an assessment of aphid infestation was carried out. A higher local density of lacewing adults, eggs and larvae over an 8-week period was observed for both the standard and the biodegradable formulation in comparison with untreated plants. Chemical analysis of the volatiles emitted from the slow-release matrix showed an active emission of the blend over at least a 4-week period. Significant biological control of aphid was measured in the vegetation surrounding the odour source. Both aphid populations were significantly reduced, with no difference between the new and the standard treatment. While coccinellids and hoverflies were not affected by the treatment, a lower number of mummified aphids were measured in some of the treated plants in comparison with untreated ones. Results show the potential for semiochemical-based targeted attraction of lacewings to enhance biological control of aphids in a prevalent monoculture field setting. Additional studies are required to support the development of practical integrated pest management guidelines, including optimization of application density, threshold value for pest and natural enemies and practical recommendation for the establishment of non-crop vegetation within and around the crop.