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Malmgren, Louise, 2011. Response to olfactory stimuli in gregarious Pieris brassicae caterpillars. First cycle, G2E. Uppsala: SLU, Dept. of Ecology



Insects search primarily to find food, egg-laying sites, resting sites or conspecifics. Understanding the search behaviour of insects at the point when they are not in contact with the host is relevant to for instance the control of pest species. There are many studies on how adult butterflies respond to different olfactory signals when distanced from the host, but less is known of how caterpillars use and respond to such signals. This study was conducted to investigate what olfactory signals attract gregarious Pieris brassicae caterpillars. Are damaged host plants more attractive than undamaged plants, or will signs of conspecifics such as frass attract the caterpillars? Furthermore, will caterpillars respond differently to different genotypes of the host?

Using four-way olfactometers, preference experiments were conducted on the genotypes broccoli (Brassica oleracea L. var. cymosa), cabbage (Brassica oleracea L. var. capitata) and cauliflower (Brassica oleracea L. var. botrytis) of the larval host Brassica oleracea. One preference experiment tested the caterpillars’ response to undamaged plants of the genotypes. In the other three experiments the response of gregarious P. brassicae caterpillars to insect-induced damage (by conspecifics), no damage, and frass treatments of each of the genotypes were tested. The results showed no difference in preference for any of the undamaged genotypes. There was also no difference in the caterpillars’ preference for any of the treatments of broccoli or cabbage, but a significant preference for damaged cauliflower over frass and the control (air). This could be explained by an attraction to the damaged plant tissue itself, or an attraction to conspecific presence because of the species-specific combination of compounds released by the plant. If the lack of difference between the undamaged genotypes is because the genotypes are equally preferred cannot be concluded before further studies have been made, comparing damaged treatments of the genotypes. It is clear from this study that caterpillars of P. brassicae respond to olfactory signals.

Main title:Response to olfactory stimuli in gregarious Pieris brassicae caterpillars
Authors:Malmgren, Louise
Supervisor:Hopkins, Richard and Ninkovic, Velemir
Examiner:Glinwood, Robert
Series:Independent project/ Degree project / SLU, Department of Ecology
Volume/Sequential designation:2011:9
Year of Publication:2011
Level and depth descriptor:First cycle, G2E
Student's programme affiliation:NK001 Biology and Environmental Science - Bachelor's Programme, 180.0hp
Supervising department:(NL, NJ) > Dept. of Ecology
Keywords:olfaction, olfactometer, caterpillar, host search, Pieris brassicae, Lepidoptera, Brassica oleracea, cauliflower, broccoli, cabbage, stimuli
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Subject. Use of subject categories until 2023-04-30.:Agricultural research
Animal ecology
Deposited On:13 Jun 2011 11:37
Metadata Last Modified:20 Apr 2012 14:20

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