Effects of habitat fragmentation and social cues on the spatial and oviposition-related behaviours of the common brimstone butterfly (Gonepteryx rhamni)

Details

Supervisors

Nieberding, Caroline M. ; Marcantonio, Matteo

Faculty

Faculté des sciences

Degree label

Master [120] en biologie des organismes et écologie, à finalité approfondie

Abstract

Although biodiversity has never been as rich as it is today, it is being changed and destroyed at an alarming rate. The main anthropogenic threats considered to be responsible for the extinction of biodiversity are changes in land and sea use (including habitat fragmentation). Species can react to these threats in four different ways: they can either disperse, acclimatise through phenotypic plasticity, adapt through genetic changes in populations, or become extinct or extirpated. However, most of the changes observed in species in response to threats primarily involve phenotypic plasticity. In particular environmental settings, a specific type of behavioural plasticity called “social learning” can serve as a key response to anthropogenic pressures. Social learning is defined as “learning that is influenced by observation or interaction with another animal or its products”. Research on social learning has almost always focused on vertebrates. However, there is growing evidence that invertebrates such as insects are also capable of learning from each other. The aim of this study was to test whether habitat fragmentation and social cues has an impact on the spatial and oviposition-related behaviours of the common brimstone butterfly (Gonepteryx rhamni). To do so, a total of 51 females were collected in 5 different locations in Wallonia (Belgium). These butterflies were tested in flight arenas divided into quadrants in which host plants had been planted following a chequered-like pattern. Trials consisted of recording three types of information during 20 minutes: the position of the individual, its behaviours, and the time spent in each quadrant and behaviour. The experiments were divided into two sequential phases (training and memory phase) for two distinct cohorts of individuals (social and non-social cohort). Individuals were tested 5 times for the training phase, one time for the short-term memory phase and one time for the long-term memory phase. During training trials, all host plants were accessible and social cues in the form of fake paper butterflies were hung near certain host plants for the social cohort. During memory trials, all host plants were hidden except the last host plant on which the individual had oviposited and a host plant on which it had never oviposited. For the social cohort, a third host plant was left uncovered: a host plant on which the individual had never oviposited and on which there was a social cue during training tests. Individuals from more fragmented habitats explored less and took less time to oviposit than individuals from less fragmented habitats. Individuals took less time to oviposit, oviposited more and spent less time escaping during the memory phase than during the training phase. Finally, the individuals of the social cohort spent less time escaping and more time resting than the individuals in the non-social cohort.