The University of Granada is using micro-computed tomography to create a 3D atlas of Euwallacea fornicatus, a pest that attacks trees on the Costa Tropical

Scientists at the University of Granada have made a significant breakthrough in the study of Euwallacea fornicatus, a tiny beetle measuring barely two millimetres that poses a serious threat to avocado crops on the coasts of Granada and Málaga. As polyphagous insects, they also threaten other ecosystems. Using computed microtomography (microCT) techniques, they have obtained detailed three-dimensional images of its internal anatomy. The aim of this work is to better understand its anatomy in order to improve the tools for identifying and monitoring this pest, the first specimens of which in Spain were detected on ornamental trees in Motril.

At first glance, Euwallacea fornicatus might go unnoticed, but its biology conceals a complexity that makes it a particularly significant pest. Native to Southeast Asia and now found in tropical and subtropical regions, this beetle does not cause its main damage by burrowing galleries in the wood, but by carrying within it symbiotic fungi that degrade the wood and on which it feeds. The insect harbours spores of specific species in specialised internal cavities called mycangia. In this species, these are located above the point where the mandibles attach. By boring into the tree with its mandibles, it inoculates the fungus, which colonises the plant’s vascular tissues, causing it to wither and, in severe cases, die. This mechanism makes it an emerging phytosanitary threat to crops such as avocado, as well as to other woody species.

An anatomical atlas to understand the enemy

To unravel the secrets of this tiny invader, Javier Alba-Tercedor, Professor Emeritus in the Department of Zoology at the University of Granada (UGR) and an international authority on microtomography applied to zoology, has used the SkyScan 1272. This instrument functions like a medical CT scanner, but with far superior resolution, capable of capturing details smaller than one micrometre. The result is a veritable three-dimensional anatomical atlas in which its organs, musculature and the mycangia where it carries pathogenic fungi can be observed with unprecedented clarity. The images are not only of great scientific value, but also possess a striking aesthetic beauty. All of this is captured in a video that offers a ‘visual journey’ into a hidden world of extraordinary complexity.

The research arose from a collaboration with the biologist Ignacio Henares Civantos, who studies the evolution of this beetle’s populations on the Granada coast using specialised traps. Henares contacted the Department of Zoology at the University of Granada to obtain high-resolution images of the captured specimens, a proposal that Professor AlbaTercedor expanded to carry out a complete microtomographic study. The ultimate aim, in the researcher’s words, is ‘to understand the enemy from the inside’, knowledge that will prove extremely useful for improving training and awareness campaigns aimed at technicians, farmers and the general public, as envisaged in the Contingency Plan for this quarantine pest in the European Union.

Scientific collaboration for pest surveillance

This work is part of a broader international project on bark beetle pests, in which

Professor Alba-Tercedor is collaborating with Dr Jakub Goczał of the University of Agriculture in Kraków (Poland). Together, they are studying the development of these insects’ flight muscles to better understand their dispersal capacity.

The results of this microtomography research will be presented at the scientific and technical conference ‘Exotic ragweed weevils on the Iberian Peninsula: Current situation and prospects’, to be held at the Faculty of Sciences of the University of Alicante on Thursday 26 March.

Contact

Javier Alba-Tercedor
Department of Zoology
Email: jalba@ugr.es

Ignacio Henares Civantos

Technical Advisor. Department of Plant Health
Regional Office for Agriculture, Fisheries, Water and Rural Development in Granada
Email: ignaciol.henares@juntadeandalucia.es

Imágenes

Image 1. Javier Alba-Tercedor and Ignacio Henares Civantos pose with some of the images obtained.

Image 2. Appearance of the tiny beetle that is the subject of the study.

Image 3. Diagram of the procedure followed for the microtomographic study.

Images 4 and 5. General view of the internal anatomy in a sagittal section.

Image 6. Detail of a frontal section of the head of the female Euwallacea fornicatus, showing details of various structures such as the brain, the mycangia, etc.