Research by BScM Candidate: Meg Collis (Research Grant 2015)
Yellow Crazy Ants(Anoplolepis gracilipes) are a major threat to the Wet Tropics World Heritage Area. They are aserious environmental and agricultural pest recognised among the world’s 100 most invasive species. Yellow Crazy Ants were first detected within the Wet Tropics World Heritage Area in 2012. The Wet Tropics Management Authority has received both state and national government funding to facilitate an eradication program through until 2019. Read more about the Yellow Crazy Ant eradication program and follow the campaign on Facebook.
Collis’ research investigated “The effect of Yellow Crazy Ants on native invertebrates: An analysis of pitfall trap contents from the ‘Wet Tropics Management Authority Yellow Crazy Ant Eradication Campaign’”. Findings from the sample area show evidence that Yellow Crazy Ant invasion results in more invertebrates but fewer native ants. The Wet Tropics Management Authority Yellow Crazy Ant Eradication Campaign periodically conducts pitfall trap sampling within and surrounding known invasion areas. This project analysed the contents of pitfall traps from three sites in the Edmonton area collected in May 2014 and February 2015.
The results were used to determine the effect within the sampled area of Yellow Crazy Ants on species richness (number of different species) of native ants, abundance of native ants, size composition of native ants and the ordinal richness and abundance of invertebrates. It was found that changes to macroinvertebrateabundance were dependent upon the density of Yellow Crazy Ants, with the most significant difference occurring with high densities of the invasive species.
High densities of Yellow Crazy Ants were also found to decrease the abundance of native ants and increase the
overall abundance of non-ant invertebrates. In this study, species richness of native ants was higher where no Yellow Crazy Ants were detected and whilst larger ants were twice as abundant in uninvaded sites, the numbers of larger ants overall was statistically low.
This study shows that there is potential in the Wet Tropics context for Yellow Crazy Ants to displace native ants resulting in changes to the biodiversity of the region. However due to the potential variability of results over seasons, long-term monitoring is recommended in the management of invasion control.
During the process of species identification, two new species of ants from the genera Vombisidris and Lordomyrma were discovered and are being held by CSIRO Tropical Ecosystems Research Centre in Darwin.
