Long-distance migration in butterflies and moths: a cross-species review

Abstract

Long-distance migration in Lepidoptera (i.e. butterflies and moths) has been studied for many years and mostly with a single-species focus. This review gives a cross-species overview of the latest developments in the multidisciplinary research field of Lepidopteran migration and is aimed to guide future research. The various methodologies that are used to study migratory Lepidoptera, their applications, advantages and disadvantages are discussed. Subsequently, an overview of the current knowledge and latest findings on Lepidopteran migration is given, including the migratory trajectories, migratory behaviour and its underlying traits and mechanisms. Many traits and genes studied thus far seem to be widespread among insects and some even among multiple animal taxa, supporting the evolutionary hypothesis that migration may be an extension of existing traits. Nevertheless, there are also variable migratory traits among species of migratory Lepidopterans. Lepidopteran migrations are found to increase in magnitude with higher temperatures, both regarding the number of migratory species detected and the number of individuals per species. This increase is hypothesised to continue in the future due to climate change. Since the majority of the current knowledge is based on only a few species, it is essential to include more species in future research so that the differences between migratory and non-migratory species can be investigated. Also, development of methodologies to follow individual animals along their lifetime tracks is of high priority, for it will enable to study all aspects of migratory behaviour in greater detail. Lastly, I recommend to study navigational behaviour in an integrated manner, i.e. combining the current knowledge on all the different compass mechanisms. Otherwise, the animals are thought to switch from one mechanism to the other in case of lacking information or inconsistency of one of the systems due to experimentation.