Parasitoid inventarisation of European corn borer (Ostrinia nubilalis Hübner, 1796) and options for its biological control in Slovenia | Inventarizacija parazitoidov koruzne vešče (Ostrinia nubilalis Hübner, 1796) in možnosti njenega biotičnega zatiranja v Sloveniji

Inglés. European corn borer (Ostrinia nubilalis) (ECB) is an important maize pest in central and northern Europe. Presently it is controlled by insecticides or biological agents such as Trichogramma brassicae in several European countries, excluding Slovenia, where the pest’s pressure is highly variable and no appropriate mechanization is available. Lessening the dependence on chemical pesticides is an integral part of the European Union’s agenda for agriculture. Mass release of Trichogramma spp. could be seen as a promising alternative for ECB control in countries with a highly fluctuating ECB pressure and no mechanization for insecticide applications. However, no records of naturally occurring hymenopteran parasitoids of ECB exist in Slovenia. To address this important under-researched topic and provide the expert basis for potential introduction of ECB egg parasitoids in Slovene maize production, a systematic inventarisation programme of ECB parasitoids was launched in 2010. Additionally, ECB flight was monitored in 2011 and 2012 at two locations in Slovenia: Jablje and Rakičan. In both locations two ECB generations  were observed. ECB was fist observed at the end of May in Rakičan. During the five years of the systematic survey we discovered two ECB parasitoid species. ECB egg masses were parasitized by Trichogramma brassicae, whereas ECB pupae were parasitized by Tycherus nigridens, with 6 or 7 % parasitation rate, respectively. T. nigridens represents a new taxon report for Slovenia. We conclude that there is a strong need for undertaking systematic surveys of natural enemies of agricultural pests.

Esloveno. Koruzna vešča (Ostrinia nubilalis) (ECB) je pomemben škodljivec koruze v srednji in severni Evropi. V številnih evropskih državah jo obvladujejo z insekticidi, kar pa ne velja za Slovenijo, saj poleg tega, da je populacijski pritisk tega škodljivca zelo spremenljiv oziroma nepredvidljiv, tudi ni na voljo ustrezne škropilne tehnike. Glede na zastavljene cilje EU, ki so usmerjeni v zmanjševanje tveganja zaradi rabe fitofarmacevtskih sredstev, je uporaba biotičnih agensov, kot je na primer množični izpust parazitoidov iz rodu Trichogramma proti ECB dobrodošla in obetavna alternativa kemičnim sredstvom. Znanje o zastopanosti in razširjenosti parazitoidov ECB iz reda kožekrilcev je v Sloveniji še vedno pomanjkljivo. Za preučitev možnosti obvladovanja ECB z biotičnimi agensi smo leta 2010 začeli sistematično spremljati navzočnost in razširjenost parazitoidov ECB na koruznih poljih. Dodatno smo v letih 2011 in 2012 spremljali nalet ECB v Jabljah in Rakičanu. Na obeh lokacijah smo odkrili dva rodova ECB. Škodljivec se je navadno pojavil najprej v Rakičanu konec maja. V petih letih raziskave smo v Sloveniji naleteli na dve vrsti parazitoidov ECB, in sicer na vrsto Trichogramma brassicae, ki smo jo izolirali iz parazitiranih jajčec ECB in na vrsto Tycherus nigridens, ki smo jo izolirali iz parazitiranih bub ECB. Stopnja parazitizma je bila 6 % za T. brassicae in 7 % za T. nigridens. Vrsta T. nigridens predstavlja novo taksonomsko najdbo za Slovenijo. Zaključujemo, da je izvajanje sistematičnega iskanja in inventarizacije naravnih sovražnikov kmetijskih škodljivcev nujnega pomena za Slovenijo.