Vedlegg

CV oktober 2017
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Sammendrag

Olfaction is the most important sensory mechanism by which many insects interact with their environment and a wind tunnel is an excellent tool to study insect chemical ecology. Insects can locate point sources in a three-dimensional environment through the sensory interaction and sophisticated behavior. The quantification of this behavior is a key element in the development of new tools for pest control and decision support. A wind tunnel with a suitable flight section with laminar air flow, visual cues for in-flight feedback and a variety of options for the application of odors can be used to measure complex behaviour which subsequently may allow the identification of attractive or repellent odors, insect flight characteristics, visual-odor interactions and interactions between attractants and odors lingering as background odors in the environment. A wind tunnel holds the advantage of studying the odor mediated behavioural repertoire of an insect in a laboratory setting. Behavioural measures in a controlled setting provide the link between the insect physiology and field application. A wind tunnel must be a flexible tool and should easily support the changes to setup and hardware to fit different research questions. The major disadvantage to the wind tunnel setup described here, is the clean odor background which necessitates special attention when developing a synthetic volatile blend for field application.

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Herbivorous insects use olfactory cues to locate their host plant within a complex olfactory landscape. One such example is the European grapevine moth Lobesia botrana, a key pest of the grape in the Palearctic region, which recently expanded both its geographical and host plant range. Previous studies have showed that a synthetic blend of the three terpenoids, (E)-β-caryophyllene, (E)-β-farnesene and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), was as attractive for the moth as the complete grape odour profile in laboratory conditions. The same studies also showed that the specific ratio of these compounds in the grape bouquet was crucial because a percentage variation in any of the three volatiles resulted in almost complete inhibition of the blend's attractiveness. Here, we report on the creation of stable grapevine transgenic lines, with modified (E)-β-caryophyllene and (E)-β-farnesene emission and thus with an altered ratio compared to the original plants. When headspace collections from these plants were tested in wind tunnel behavioural assays, they were less attractive than control extracts. This result was confirmed by testing synthetic blends imitating the ratio found on natural and transformed plants, as well as by testing the plants themselves. With this evidence, we suggest that a strategy based on volatile ratio modification may also interfere with the host-finding behaviour of L. botrana in the field, creating avenues for new pest control methods.

Sammendrag

In nature plant terpenoids play multiple ecological roles. Many phytophagous insects use them as kairomones to locate their host plants. This is also the case for Lobesia botrana, which is the main pest of European vineyards. It was found that a specific blend of the terpenoids (E)-β-caryophyllene, (E)-β-farnesene and the homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene emitted by grapevine was attractive to L. botrana females, and the attractiveness was shown to be dependent on the kairomone ratio. In this work, we generated stable grapevine transgenic lines with altered (E)-β-caryophyllene and (E)-β-farnesene emission compared to natural plants. Thus, we modified the ratio between these two kairomones in vivo, and tested how it affected L. botrana behaviour.

Sammendrag

The pea moth Cydia nigricana (Lepidoptera: Tortricidae) is the key pest of the pea Pisum sativum (Fabaceae). Alternative pest control techniques need to be developed since efficient control options are scarce. Field studies in Northern Hessen, Germany, in the years 2006 - 2008 demonstrated a strong correlation between the seasonal flight period of C. nigricana and the phenology of pea. With this starting point, we propose to study the olfactory space between the pea plant and the pea moth, aiming to identify volatile cues encoding host recognition and host finding in pea moth females, and the potential use of these compounds for control of the pea moth. As a first step, two-choice experiments in the laboratory concerning complex plant odours were conducted to study the preference between different phenological development stages of pea plants using male and female C. nigricana (mated and non-mated). Males and non-mated females showed no preference, whereas mated females clearly preferred flowering pea plants. To study the host finding behaviour and upwind orientation of C. nigricana we conducted wind tunnel experiments, using pea plants in different phenological development stages. The preference of mated females for the pea flower has been confirmed and additionally, high attraction of mated females for the late bud stage was recorded. Overall, the flower and the late bud stage of P. sativum seem to be the most important phenological development stage of pea for host finding behaviour of C. nigricana. The next steps in this study are the identification, selection and characterisation of behavioural active pea plant compounds.