engleski

Native parasitoid assemblages of an invasive pest, Dryocosmus kuriphilus (Hymenoptera: Cynipidae), in Slovenia, Croatia and Hungary

The Asian sweet chestnut gallwasp, Dryocosmus kuriphilus (Hymenoptera, Cynipidae) is considered to be the most important pest of chestnut worldwide. Originating from China, this pest was accidentally introduced to Japan in 1941, colonized Korea in 1958 and the USA in 1974. In 2002 it was detected in Europe, Italy. Since then DK spread throughout Italy and has also been reported in all European countries where chestnut grows. Within the native range in China, 11 parasitoids species were found to associate with D. kuriphilus which kept the host populations at low densities ; in Japan, South Korea, the USA and European countries the attack rates of indigenous parasitoid species vary from 2% to 4.7%, We studied the native parasitoid assemblages of D. kuriphilus across it expanding range in Italy (since 2005), Slovenia (since 2010), Croatia (since 2011) and Hungary (since 2013). All parasitoid species are known to associate with oak cynipid galls. Most of them are generalists that can shift hosts more easily and are more successful in colonizing an invasive host and thus a large parasitoid diversity within the DK community can be expected. The aim was to study the source community of parasitoids available to attack the invasive host and the way in which they may associate with D. kuriphilus. Since 2005, 44 species shifted onto the new pest, D. kuriphilus. In Italy, 39 chalcidoid parasitoid species have so far recruited naturally to the new host, 28 in Slovenia, 20 in Croatia 20, and 17 in Hungary. The time lag between the introduction of the new host, D. kuriphilus, and the recruitment of native parasitoid community is short and depends on the longevity of pest’s presence on a particular site. Recruitment of parasitoids to D. kuriphilus depends on actual parasitoid species composition of oak gallwasps to be found in the same locality and varies from year to year.

sweet chestnut; parasitoid recruitment; host shift

nije evidentirano