How Argentine fireflies threaten Spanish soil health

Spain’s already worrying progress of desertification has a new threat in the form of Argentine fireflies. There is great concern among scientists on the Iberian Peninsula.

Argentine fireflies, a recently introduced species, threaten native earthworm populations that are crucial to soil health and agriculture. The firefly, called Photinus signaticollis

, native to South America, has established itself in Spain since 2016. The insect has spread to the northeast of the peninsula and even crossed the Pyrenees into southern France in 2019.

The larvae of these fireflies feed on earthworms. Therefore, their growing presence could negatively impact these organisms essential to soil health.

The extent of the invasion is still unknown

Researchers from the Department of Biodiversity, Ecology and Evolution of the Universidad Complutense de Madrid are sounding the alarm: the scale of the invasion and the ecological niche that these fireflies will occupy in Europe remain unknown. Using species distribution models, the scientists identified areas in Europe where these fireflies could potentially establish themselves.

Why in Northeast Spain?

In their native South America, Photinus signaticollis

are mainly found in the temperate regions of Argentina and Uruguay, where the climate in some places closely resembles that of the western Mediterranean coast. This climate similarity has allowed fireflies to become established in the western Mediterranean.

“Using species distribution models, we have identified highly suitable areas across Europe where this firefly could become established if introduced. Interestingly, using only data from South America and associated state models, we can predict exactly where it will occur in Europe. There are climatic similarities between the birth area around Río de la Plata and the province of Girona,” the researchers emphasise in a statement.

No natural enemies

The lack of natural enemies in Europe seems to promote the rapid spread of P. signaticollis

. The research team points to the lack of resources, specialists, and attention for biological invasions, which increases the problems surrounding exotic species. The university adds that these “neglected invasive species” are a growing problem. The lack of resources to tackle such invasions can create several challenges and threats from exotic species.