IOBC wprs Symposium, Dachau 1998

Scents in Orchards

Plant and Insect Semiochemicals from Orchard Environments


The goal of the meeting is to bring together people from various fields interested in behaviourally active compounds of plant and insect origin, especially from orchard environments.

Orchards are a source of a manifold of odours which rule interactions between plants and herbivores, their predators and parasites, and between sexes of the same species. In spite of an inherent diversity, structurally related compounds occur at different trophic levels across taxa, fulfilling various functions.

Flavors help both insects and humans to identify savoury and palatable fruit - some insects are known to sequester these compounds into sex pheromones. Physico-chemical, biosynthetic and physiological mechanisms, and the evolutionary context serve to explain links and commonalities. Different disciplines view these chemicals from different perspectives, employing different experimental approaches.

Plant volatile compounds

A wealth of knowledge on plant volatiles has been acquired by chemists interested in flavor chemistry, plant physiology and biochemistry. This knowledge is a most valuable resource for entomologists attempting to identify plant volatile compounds that attract insects to food sources, mating and oviposition sites. The potential of attractant or deterrent plant compounds for insect control is hardly exploited at all.

Yet, the impressive listings of volatile compounds identified from various natural products are far from complete. Shortcomings become apparent especially when looking at volatile collections through the insect antenna; its astounding sensitivity and specificity highlights the importance of analogues and isomers, or of compounds present in small amounts - that may nevertheless elicit strong behavioural responses. The sweet, fruity smell of codling moth sex pheromone to the human nose is due to trace amounts of a geometric isomer, the sex pheromone of a related moth.

Semiochemicals and pheromones in non-lepidopteran insects

The practical use of semiochemicals for insect control is still largely restricted to moth pheromones. Compounds and methods need to be made available to monitor or control economically important species belonging to other taxonomic groups.

Mating disruption

Lepidopteran sex pheromones are a particularly well-investigated class of compounds. Their use for environmentally safe control of key species such as Oriental fruit moth or codling moth has become a reality during the past decade. A concerted effort of the scientific community, industry and growers must now be made to consolidate these achievements and to establish mating disruption as a reliable and cost-efficient technique.

Meeting site

The meeting will be held at Dachau, a 1200-year-old town close to Munich. As you all know, Dachau gained a most deplorable reputation during recent history. However, I am confident that the ancient part of town will be a hospitable forum for the meeting. In addition, Dachau is only a short commuter train ride from the centre of Munich.

0-05-01 peter.witzgall@phero.net