Epitrix (flea beetle) species, life cycles and detection methods (Epitrix II)

Epitrix Foudras 1860, is a genus of flea beetles (Coleoptera: Chrysomelidae: Alticinae) with nearly 180 species worldwide. Most species occur in South and Central America (neotropics), and only 12 and 10 species are known from North America and Europe, respectively. A few species of Epitrix are reported to feed on potato plants, the adults feeding on the leaves and the larvae on the roots and tubers. In the European Union (EU) emergency measures have been introduced to prevent the introduction of the EPPO A1 listed species Epitrix tuberis and E. subcrinita and the spread of the EPPO A2 species E. cucumeris and E. papa, accidentally introduced in Portugal and Spain. The three former species are native from North America and are known to cause damage to tubers, with E. tuberis being the most damaging one. E. papa is a newly described species with unknown geographic origin and known distribution limited to some regions of Portugal and Spain and causes damage to tubers. Other neotropical Epitrix species could also be of concern for European phytosanitary authorities, such as E. yanazara, which are known to feed on potato. Further research into the taxonomy and pest status of other potential Epitrix species of concern within the neotropics is required to understand these lesser-known species better and the impacts they may pose to other regions.

This project utilises the expertise of a network of scientists developed during Euphresco Epitrix I project to increase knowledge, understanding and preparedness for potential new outbreaks of Epitrix spp. affecting potato crops.

Epitrix species are uniform in their external morphology and difficult to distinguish in the field or in the laboratory even by specialists. Taxonomic experts from affected areas in Europe and North America prepared samples of accurately identified Epitrix beetles to help validate molecular detection methods for the benefit of the plant inspection services, particularly for regions where this expertise does not exist. Validated methods are now ready for interlaboratory comparative tests, which will be carried out in autumn 2021.

Many new potential pest Epitrix spp. were collected on solanaceous plants during a field expedition to Peru in 2020. This material will be used to help to bridge the knowledge gap of lesser-known Epitrix species within the neotropics.

Plant volatile organic compounds (VOCs) were investigated in EPITRIX I in the laboratory and in field experiments as potential attractants for detecting and monitoring Epitrix. Further research into the attractiveness of the VOC substances were studied, and although the results were encouraging, the attractiveness of the substances tested in the field was insufficient for reliable insect detection and monitoring. An additional study for testing new attractants (plant and insect volatiles) was therefore proposed but unfortunately not funded.

Available licensed insecticides and cultural management practices were reviewed to ensure that chemical control measures are still feasible, as several widely used pesticides have recently been removed from the market or are under review in the EU and the United Kingdom. The study showed that cultural practices (such as crop rotation, dates of planting, plantation of a trap crop, destruction of crop residues, and control of solanaceous weeds) may be used for efficiently disrupting the insect’s biology and target control.