First record of Epitrix similaris in Portugal: addition to the EPPO Alert List
The NPPO of Portugal recently informed the EPPO Secretariat of the first record of Epitrix similaris (Coleoptera: Chrysomelidae) on its territory. The identification was done by the Portuguese National Institute of Biological Resources. The insect is reported to be quite widespread in potato production areas. The proposed control measures are: crop rotation without any Solanaceae crops, and destruction of plant debris and weeds. Chemical control is targeted against the adults, to prevent new life cycles from being initiated especially at the beginning of the season.
EPPO note: Epitrix similaris is a North American insect which had so far never been reported in Europe, and for which there is very little information in the literature about its geographical distribution, host plants or economic importance. It can be recalled that on the EPPO A1 List, only E. cucumeris and E. tuberis are included. Arnett (2000) mentions that among the 12 Epitrix species which occur in North America, only 5 are considered as pests (i.e. E. cucumeris, E. fuscula, E. hirtipennis, E. subcrinita and E. tuberis) and this list does not include E. similaris. Seeno and Andrews (1972) recorded the occurrence of E. similaris together with E. hirtipennis, E. subcrinita and E. tuberis in California (US), and stated that these species were primarily associated with solanaceous crops, although adults appeared intermittently on beans, sugarbeet and cucurbits. Although much data is lacking on the biology and economic impact of E. similaris on potatoes and other solanaceous crops, the EPPO Secretariat decided to add it to the Alert List to draw the attention of the NPPOs to the introduction of this new potato pest in the EPPO region.
Epitrix similaris (Coleoptera: Chrysomelidae)
Why: In Portugal, unusual damage to potato crops (superficial lesions on the tubers) started to be observed in 2004 in the north of the country (near Porto). In the following years, damage continued to spread towards the south but the causal agent remained unknown. In 2008, Epitrix similaris was identified in Portugal and was considered to be responsible for this unusual type of damage. However, at this point, it still cannot be excluded that other species of Epitrix might be also be involved because of the difficulties encountered in identification (members of the Alticinae sub-family are small insects with similar morphology). Studies are continuing in Portugal to better understand the biology of this new pest and its association with the damage observed. Considering the importance of potato crops in Europe, and the possible similarities that E. similaris could present with other listed pests (E. cucumeris and E. tuberis – both EPPO A1 List), the EPPO Secretariat decided to add it to the Alert List.
Where:
EPPO region: Portugal (mainly in the north and centre; E. similaris is reported to be widespread in potato-growing areas).
North America: USA (at least California). E. similaris is considered to originate from North America, but very little data is available on its geographical distribution in its area of origin.
On which plants: Potato (Solanum tuberosum) and other Solanaceae, such as tomato (Lycopersicon esculentum), aubergine (S. melongena), tobacco (Nicotiana tabacum), Capsicum sp., and weeds (Datura stramonium, S. nigrum). Adults can occasionally feed on leaves of other plant families (Chenopodiaceae, Cucurbitaceae, Fabaceae).
Damage: Affected potato tubers show long corky lesions and small superficial warts. These lesions are caused by larvae (whitish, slender, with a brown head) which feed under the epidermis, these galleries usually remain superficial and do not affect the flesh of the tuber. Adults (small, black beetles 1.5-2 mm long) cut characteristic shot-holes in potato leaves (1-1.5 mm diameter). In Portugal, the yield of potato crops is apparently not affected but the commercial value of the tubers is reduced. Severely disfigured tubers are rejected in trade. Concerning the pest’s impact in its native area, the EPPO Secretariat could not find any record of economic damage caused by E. similaris on potatoes or other solanaceous crops in North America.
Although data is Iacking on the life cycle of E. similaris, it is probably similar to other Epitrix species. Adults overwinter in the soil and crop debris, and emerge in spring. Eggs are laid in the soil near the base of potato plants. Newly hatched larvae move towards the root system and start to feed on tubers. Pupation then takes place in the soil. It is considered that under favourable conditions, there may be at least two generations per year.
Dissemination: Adults can fly actively and it can be noted that the spread of E. similaris in Portugal has been rather fast. Potato tubers or soil attached to the tubers could carry the pest (as larvae, pupae or overwintering adults) over long distances.
Pathway: Potato tubers from countries where E. similaris occurs, soil from countries where the pest occurs.
Possible risks: Potatoes are widely grown across Europe and are of major economic importance. Other solanaceous hosts, such as tomato, aubergine and capsicum might also be at risk but so far in Portugal, damage is only reported on potato. Cultural and chemical control measures are likely to be effective against E. similaris but more practical experience is needed to verify this assumption. More studies are also needed to determine the economic impact of E. similaris on potato and eventually on other solanaceous crops. Although it is unlikely that the natural spread of E. similaris can be stopped, it seems advisable that precautions should be taken to delay it and to prevent introductions of other Epitrix species into the EPPO region.
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EPPO RS 2009/022
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Panel review date: -
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Entry date 2009-02
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Sources
NPPO of Portugal, 2009-01.
Arnett RH Jr (2000) American Insects. A handbook of the insects of America North of Mexico, 2nd edition, CRC Press (US), 1003 pp.
Oliveira R, Chatot C, Dedryver CA (2008) Détectée en Europe, une nouvelle altise. Potato Planet, juillet, 30-34.
Seeno T, Andrews F (1972) Alticinae of California, Part 1: Epitrix spp. (Coleoptera: Chrysomelidae). The Coleopterist's Bulletin 26(2), 53-61 (abst.).
Silva N (2008) Novo praga ameaça batata portuguesa. Frutas, Legumes e Flores, no. 101, 12-13.
INTERNET
Centro Operativo e Tecnológico Hortofrutícola Nacional. Balanço da campanha batata. Relatório. http://www.cothn.pt/files/7762_Relatori_4939003baf4de.pdf
Instituto Nacional de Investigação Agrária e das Pescas (Portugal) Pragas – Epitrix similaris. http://www.iniap.min-agricultura.pt/ficheiros_noticias/folhetoEpitrixemBatateira.pdf
Moreira J, Belchior A (2007) Estudo comparativo de cultivares de batata em dois modos de fertilização azotada, conduzido em sistema de produção integrada. http://www.drapc.min-agricultura.pt/base/geral/files/realtorio_batata_2007.pdf