The impact and spread of the invasive garden ant: an alien invasive species in the UK

Alongside climate change and habitat loss, invasive non-native species are a major threat to the natural world. Ants are amongst the most widespread and damaging invasive species. The invasive garden ant, Lasius neglectus, has only recently been detected in the United Kingdom and is the country’s first invasive ant species. This thesis aims to assess the impact and spread of this species in the UK. In this thesis I carry out a UK-wide risk assessment for the species and develop a protocol for experimentally assessing its potential impact on an economically important crop plant. I investigate behaviours that may contribute to its success as an invasive species. I evaluate the feasibility of commonly used pesticides for the control of Lasius neglectus, and conclude that granular products, while convenient for large-scale application, are not suitable for this species due to low palatability; this may hinder future control attempts. I carry out a large-scale survey to assess the distribution of this easily-overlooked species, and conclude that while it is not as widely distributed in botanic gardens as expected, the number of urban sites where it occurs is increasing rapidly. In conclusion Lasius neglectus is difficult to detect and hard to eradicate once established, so efforts should be made to reduce its spread from the areas in which it currently occurs.