A rearing technique for producing Epitrix similaris Gentner (Coleoptera: Chrysomelidae: Alticinae)

The flea beetle species Epitrix similaris Gentner was identified in mainland Portugal in 2009, following the detection around 2004 in the Oporto region of an unusual type of potato tuber damage, similar to that caused in North America by the economically important tuber flea beetle Epitrix tuberis Gentner. This was the first finding of E. similaris, an american species, in Europe and in the EPPO region. By contrast to E. tuberis, a well studied species, no information exists on the biology, behavior, host-range and population dynamics of E. similaris to base adequate and efficient control strategies. Because of the subterranean development of the larvae, the small size and high mobility of the adults, the field studies necessary to collect data on the population dynamics and damage, for determining the most adequate timing and control strategies are difficult to carry-out with natural populations. To circumvent this constraint we developed at INIAV a rearing technique for producing adult insects of the species E. similaris for the artificial infestation of laboratory and field experiments. The insects are reared inside cages kept in a walk-in climate-controlled chamber (temperature 22 +/- 0.5 degrees C, 16h day-length, and 64%-84% relative humidity). As host-plants, juvenile potted plants of aubergine (Solanum melongena L.) and small potted plants of potato (Solanum tuberosum L.) are used. The host plants are produced in a separate chamber, and later introduced in the insect rearing unit to be exposed to adult insects during three weeks, for oviposition to occur. After this period, the plants are cleaned off from adults, removed from the oviposition cage and transferred to smaller emergence cages, where the immature stages present in the soil are allowed to complete their development. Each pot is kept 5-7 weeks in the emergence cage. The adults are daily collected with entomological mouth aspirators, and either used for the experiments or reintroduced into the production cycle. The cultures are refreshed twice per year with insects collected from the field, in order to preserve a large genetic base in the insect cultures.