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The caterpillars feed on oak leaves, stripping trees bare to their bark. This weakens the trees, increasing their vulnerability and susceptibility to threats, diseases, other pests, and harsh environmental conditions (EFSA, 2009).

Health risks:

One caterpillar can carry up to half a million bristles. These hairs, which can travel up to 500 metres, contain Thaumetopoein, an allergenic protein that can cause skin rashes, eye complaints, and respiratory problems like pharyngitis and asthma (Maier et al., 2003; Rahlenbeck & Utikal, 2015).

Current methods:

Current products are non-specific, affecting other species of caterpillars and damaging the environment; these measures do not succeed at conservation of flora and fauna around the OPC's habitat. For more information you can watch our interview with Jules Sondeijker, OPC control expert: (J. Sondeijker, personal communication, May 7, 2020).


The OPC is the larvae of the Oak Processionary Moth (OPM) (Thaumetopoea processionea), a major invasive species spreading rapidly from its native parts of Central and Southern Europe. (Groenen & Meurisse, 2011).

It owes its name to the larvae's behavioural trait of forming long processions when in search of food during the night (Koppert Biological Systems, 2020).

The OPC has already established significant populations in western and northern areas of Europe, including France, the Netherlands, Germany, Belgium, and even all the way to the UK. Climate change has been thought to aid and advance this spread (van Oudenhoven, van Vliet & Moraal, 2008).


The MSP-Maastricht team aims to develop a biological, environmentally friendly insecticide that is specific to the OPC.

In order to develop this new tool for population control of the pest, essential target genes unique to the species were identified. Subsequently, short interference RNA molecules (siRNAs) are used to inhibit the production of the corresponding proteins needed for the development of the caterpillar. In any other species, these siRNA would degrade rapidly, without causing any harm. However, for the target insect, it leads to a decrease in population.

Potential siRNAs were identified using BLAST, and the precursor will be delivered through genetically modified bacteria that can survive the environmental conditions.