Native and invasive ladybirds in a changing U.K. climate

Native and invasive ladybirds in a changing U.K. climate

How are native and invasive ladybirds impacted by the changing U.K. climate?

Project Description

Climate change and invasive species have been described as a “deadly duo”. We have the potential to explore the interacting effects of these drivers of biodiversity change using ladybirds as a model system. Some native U.K. ladybirds have declined in recent years, in part as a result of the establishment and spread of an invasive ladybird species, the Harlequin ladybird (Harmonia axyridis), which now dominates many U.K. landscapes. The native 2-spot (Adalia bipunctata) and 7-spot (Coccinella septempunctata) ladybirds have decreased in distribution. Native and invasive ladybirds interact through competition for aphid prey and through intraguild predation, where invasive species are often stronger competitors and more voracious predators.

These interspecific interactions, and changes in species distribution and abundance, are taking place in the context of a changing U.K. climate, including increases in summer temperature, greater fluctuations in temperature (e.g., more prolonged periods of extreme heat and associated drought), and milder winter temperatures coupled with periods of extreme winter weather (cold and snowfall). These climate factors are likely to affect ladybird behaviour, physiology, and interactions with other species – including prey and competitors – and are therefore likely to affect the abundance and stability of native ladybird populations. There is now a critical need to understand how native ladybird species respond to the combined threats of invasive species and a changing climate.

This studentship will investigate effects of climate change on 2-spot and 7-spot ladybird behaviour and physiology, and how these effects impact interactions with the invasive Harlequin ladybird. Possible research questions to be addressed include:

  • How do higher summer temperatures and heat waves impact native and introduced ladybird feeding behaviour and interactions with aphid prey? Higher temperature is associated with higher activity and metabolism in many insects, which should increase feeding; however, thermal stress should impair feeding. Temperature effects on feeding are likely to impact relative competitive ability between native and introduced species.
  • How will the changing climate impact population stability in native and introduced species? In addition to direct effects of temperature on reproductive capacity and survival, the changing climate is also likely to influence the degree of synchrony between ladybird and aphid prey populations.  Laboratory experiments will be complemented by large-scale modelling that tests whether patterns of land-use offset climate effects.
  • How do milder winter temperature impact native and introduced ladybird survival during diapause and overwintering emergence?
  • Are different colour morphs affected differently by changes in summer and winter temperature? The black melanic morph warms faster and is at higher risk of overheating, compared with the red-non-melanic morph.
  • What is the physiological response to thermal stress for native and introduced ladybirds? Using metabolomics approaches, which capture a snapshot of physiological state at a cellular level, it is possible to detect thermal stress at a physiological level that is buffered and masked at a whole organism level.
  • How do changes in behaviour and physiology, in turn, mediate interspecific interactions, with outcomes for population dynamics and community composition? Temperature influences activity, and will therefore affect encounter rates between cannibal predators and intra-guild prey among ladybird species, and between ladybirds and their own predators and parasitoids. Differences in both predatory efficiency and susceptibility to parasitoids between native and invasive species are thought to influence their relative success.

The approaches will include laboratory experiments using controlled temperature rooms and incubators to evaluate temperature effects under controlled conditions, and trials under natural and semi-natural conditions. The student will benefit from broad training in evolutionary ecology and entomology in Dr. Perry’s lab, which investigates the ecological context of reproductive and sexual behaviour in ladybirds, fruit flies and other insects.

Aims of the Project

The aims are to evaluate how the changing climate – including increasing summer temperature, periods of extreme heat, and milder winter temperatures – impacts behaviour,  population growth and stability of native and invasive ladybirds; to evaluate physiological responses to thermal stress; and to assess how temperature mediates direct interactions between native and invasive ladybirds.

Methods

Experimental approaches will include laboratory experiments using controlled temperature rooms and incubators and field trials. There will also be opportunities to investigate ladybird physiological responses to temperature at a cellular level, using metabolomics. Additionally, the large-scale and long-term datasets held by the Biological Records Centre within CEH will provide an opportunity for correlative modelling approaches to inform the mechanistic experimental approaches.

Specialised Skills required

No specialist skills are required. Training will be provided in experimental design, behavioural assays, insect biology, and data collection and analysis, as well as the presentation of results and writing scientific publications. There will be opportunities to investigate ladybird physiological responses to temperature at a genetic and cellular level, using transcriptomics and metabolomics; training will be provided.

Please contact Jen Perry jennifer.perry@zoo.ox.ac.uk

 

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