Olfactory learning in Pieris brassicae butterflies is dependent on the intensity of a plant-derived oviposition cue
Creators: name: Peftuloglu, Dimitri
name: Bonestroo, Stefan
name: Lenders, Roos
name: Smid, Hans
name: Dicke, Marcel
name: van Loon, Joop
name: Haverkamp, Alexander
Publisher: name: Zenodo
Year: 2024
Subjects: olfactory conditioning
Oviposition stimulus
Glucosinolates
Lepidoptera
Pieris brassicae

description: Butterflies, like many insects, use gustatory and olfactory cues innately to assess the suitability of an oviposition site and are able to associate colours and leaf shapes with an oviposition reward. Studies on other insects have demonstrated that the quality of the reward is a crucial factor in forming associative memory. We set out to investigate whether the large cabbage white Pieris brassicae (Linnaeus) has the ability to associate an oviposition experience with a neutral olfactory cue. In addition, we tested whether the strength of this association is dependent on the gustatory response to the glucosinolate sinigrin, which is a known oviposition stimulus for P. brassicae. Female butterflies were able to associate a neutral odour with an oviposition experience after a single oviposition experience, both in a greenhouse and in a semi-natural outdoor setting. Moreover, butterflies performed best when trained with concentrations of sinigrin that showed the strongest response by specific gustatory neurons on the forelegs. Our study provides novel insight into the role of both gustatory and olfactory cues during oviposition learning in lepidopterans and contributes to a better understanding of how these insects might be able to adapt to a rapidly changing environment.
description: Funding provided by: Dutch Research CouncilROR ID: https://ror.org/04jsz6e67Award Number: 016.Veni.192.116
Funding provided by: Dutch Research CouncilROR ID: https://ror.org/04jsz6e67Award Number: SPI87-313
description: Butterflies were conditioned by spraying 1 ml sinigrin solution on a green paper disc (9.5 cm in diameter) as an unconditioned stimulus, coupled with 20 microliters of vanilla scent as a conditioned stimulus. Three different concentrations of sinigrin solution were used. 3 different conditioning treatments plus one group of non-conditioned naive animals --> four different treatments. Tests consisted of releasing one animal in a testing environment provided with four green paper discs, identical to the ones used during training, but without sinigrin. Two of these were scented with vanilla scent, while the other two were scented with 30% alcohol-water solution. Each test lasted 30 minutes. Parameters recorded for each test are listed and explained below. Please note that not all of the recorded parameters have been used for analysis.

Electrophysiology

Response of the trichoid taste sensilla to sinigrin was assessed with single sensillum recordings. Sinigrin was dissolved in 1 mM KCl, 4 different concentrations were used (1, 10, 20, 30 mM), while 1 mM KCl was used as blank control. The foretarsi of female Pieris brassicae present two different sensilla classes, namely medial and lateral, with two clusters for each class. One random sensillum for each class was screened for responses to sinigrin.