The effects of anthropogenic noise on the behaviour of a terrestrial invertebrate

: the field cricket (Gryllus bimaculatus)

Abstract

Many animals are increasingly facing human-induced environmental changes. Anthropogenic noise is globally recognised as a major environmental pollutant that has become omnipresent in aquatic and terrestrial environments. Anthropogenic noise changes the acoustic environment through an increase caused by human activities. The majority of studies on the effect of anthropogenic noise on animal behaviour have focused of aquatic and terrestrial vertebrate species. However, little is known about the effects of noise on the behaviour of invertebrates. Invertebrates are diverse and account for the majority of animal species, and are essential for ecosystem functioning, providing numerous ecosystem services. Studying how invertebrates are affected by anthropogenic noise is important because behavioural response of species to changing environments play a key role in enabling species to adjust to human-induced environmental changes. Therefore, in this thesis, I employ comparative and experimental approaches to investigate the effects of noise and its amplitude on the behaviour of invertebrates. I used field crickets G. bimaculatus as a terrestrial invertebrate species to study the effects of anthropogenic noise on invertebrate behaviour. I first conducted a meta-analysis to quantify the effects of anthropogenic noise on the order Orthoptera which allow us to quantify the effects of noise holistically. Overall, I found that anthropogenic noise affects male calling, mate choice, and life history in various Orthoptera species. Second, I used a playback experiment to test whether crickets adjust their foraging, sheltering, and movement behaviour in the presence of anthropogenic noise. I found that noise exposure caused a decrease in the number of individuals reaching food and individuals took longer to reach the food when exposed to noise. I also found that during noise-exposure, crickets took less time to reach the shelter and spent more time in the shelter than in the pre-noise exposure stage. Furthermore, in the pre-noise exposure stage, crickets spent more time moving than in the during noise-exposure stage. Third, I tested how noise affects receivers’ ability to locate signallers, by exposing male and female crickets to three different acoustic playback treatments consisting of male cricket songs, anthropogenic noise, and male cricket songs with noise. I found that anthropogenic noise affects behavioural responses, leading to differences in the latency to move, and the pattern of the response differed between males and females. Moreover, anthropogenic noise decreased the time individuals spent moving and that also differed between sexes. Finally, I tested whether differences in anthropogenic noise amplitude elicit different behavioural responses. I found that the highest amplitude of noise had the most effect on crickets. The findings indicate that anthropogenic noise has an impact on various key behaviours of invertebrates. These findings are crucial in the context of conservation because when identifying areas to protect invertebrates, my results show that it is essential to consider the effects of noise on invertebrate behaviour.

Thesis embargoed until 31 July 2026.

Date of Award	Jul 2024
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Umm Al Qura University
Supervisor	Hansjoerg Kunc (Supervisor) & Domhnall Jennings (Supervisor)