Pea odorants guide host finding behaviour in pea moth: a new strategy for sustainable insect management
Final Report Abstract
The aim of this project was the identification of host plant volatiles responsible for pea moth Cydia nigricana Fabricius (Lepidoptera: Tortricidae) host location as a tool to develop a new strategy for pea moth control using kairomones. The results showed the ability of mated females of C. nigricana to discriminate among phenological stages of pea plants and demonstrated a clear preference for plants during flower development. Males and virgin females did not show this ability. Thus, the flowering stage of pea and the associated odour profile were crucial for the host location behaviour of mated females. Those moths distinguished not only between pea plants at different phenological stages based on a combination of visual and volatile cues, but also between odour collections of the corresponding plants, i.e. sensing volatile cues of the host only. It has been shown that for mated females of C. nigricana odour is the fundamental host plant cue and that visual cues are needed for the insects to show its whole behavioural sequence. The behavioural assays, identification of the volatile content and recording of antennal activity provided a first indication of which volatiles may be important for host location in female C. nigricana. In total, 27 compounds were identified from odour profiles of pea plants at different phenological stages (leaf, bud, flower, pod) as well as from detached buds and flowers, ten of them were antennally active, and nine of them were antennally active and pea flower specific. Synthetic analogues of these nine flower specific and antennally active volatiles resulted in high attraction response of female C. nigricana in the wind tunnel and in the field. The results showed that two monoterpenes were fundamental volatile cue for pea moths’ host location and two alcohols had a strong synergistic effect on female attraction if mixed with these monoterpenes. The recorded trap catches of female C. nigricana in the field despite the superior competition of a flowering pea field as background odour are an indication for possible effective synthetic attractants. Analyses of odour profiles of flowering pea plants depending on diurnal rhythm and the respective behavioural response of the moths towards these volatiles in the wind tunnel indicated that the flight activity time is synchronized with the variation in release of key volatiles affecting the host location behaviour of C. nigricana. Furthermore, analyses of odour profiles of several pea cultivars and other host plants species of C. nigricana and the behavioural response to these host specific odour profiles in the wind tunnel showed that the suitability of a host plant is partly linked with the variation in release of key volatiles affecting the host location behaviour of C. nigricana. The overall findings provide a promising basis to develop the implementation of kairomones in pea moth control and further studies are in progress.
Publications
- Pea odorants guide host finding behaviour in pea moth: a new strategy for insect management. IOBC/wprs Bulletin (in progress). IOBC wprs working group meeting ‘Integrated protection of field vegetables’, Bäckaskog slott, Sverige, 2011
Thöming, G., Saucke, H. & Knudsen, G.K.
- 2012. Blatt, Knospe, Blüte oder Hülse – wann kommt der Erbsenwickler zur Erbse? Mitteilungen der Deutschen Gesellschaft für allgemeine und angewandte Entomologie 18: 237-240. Entomology Congress, Berlin, Germany, 2011
Thöming, G. & Saucke, H.
- Ein Lockstoff für den Erbsenwickler? Erste Ergebnisse zu Wirtspflanzen-Duftstoffen in Windtunnel- und Freilandstudien. Julius-Kühn-Archiv 438: 147. Deutsche Pflanzenschutztagung, Braunschweig, Germany, 2012
Thöming, G., Norli, H.R., Saucke, H. & Knudsen, G.K.
- Pea flower volatiles to control the pea moth – first results from wind tunnel and field experiments. IOBC/wprs Bulletin (in progress). IOBC wprs working group meeting ‘Pheromones and other Semiochemicals’, Bursa, Turkey, 2012
Thöming, G., Norli, H.R., Saucke, H. & Knudsen, G.K.
