Temperature and humidity are important factors for the survival of insects, and insects have developed a wide range of plastic responses to deal with changes in these factors. Phenotypic plasticity is a species ability to express different phenotypes, from a single genotype in response to changes in their environment. While changes to temperature have been well studied, changes in humidity and its interaction with temperature are much less studied. This study aims to address this by examining how the morphology and behaviour of Pachnoda marginata (P. marginata) is affected by differences in temperature and substrate moisture. P. marginata are a species of beetle from across central and western Africa, found in both dry and humid environments. Eight males and eight females were kept in four separate tanks of varying temperature and substrate moisture, simulating different environments over a period of several months, with behavioural and morphological traits/measurements collected. The results from the study showed a lack of evidence to support Bergmann and Allen’s rules as temperature had no effect on the weight, leg length or claw curve of the P. marginata. However, evidence for phenotypic plasticity was found, with P. marginata at lower temperatures seen wandering in the surface more frequently, being smaller and having shorter limbs in high temperature and low substrate moisture environments and more eggs being retained by female P. marginata in low temperature and substrate moisture environments. These results lead to the conclusion that temperature and substrate moisture can result in trade-offs between reproduction and survival as well as showing how the P. marginata are able to effectively adapt to different environments with plastically induced changes.
- Plasticity
- Behaviour
- adaptation
- Beetle
- Master of Science by Research (MScRes)
Phenotypic Plasticity of Pachnoda marginata in response to Temperature and Substrate Moisture
Legg, W. (Author). 13 Jul 2026
Student thesis: Masters by Research