Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Diversity of parasitoid assemblages of native and alien leaf miners in Croatia.

Abstract

Croatia has rich native leafminer fauna with recently added alien and invasive species. Phyllonorycter roboris, Phyllonorycter quercifoliella, and Tischeria ekebladella on Quercus robur and Quercus petraea, Phyllonorycter klemannella ([ Phyllonorycter klemannellus]) on Alnus glutinosa are native leafminers. Phyllonorycter robiniella, Parectopa robinella on Robinia pseudoacacia, Phyllonorycter platani on Platanus sp., Cameraria ohridella on Aesculus hippocastanum and Phyllonorycter leucographella on Pyracantha coccinea were recently introduced invasive species in Croatia. The hypotheses: (a) native parasitoids have adapted to new hosts, (b) these parasitoid species are generalists, (c) native and alien species of leafminers with similar bio-ecological characteristics have similar parasitoid assemblages were tested. The research was carried out from 2004-2006 in forests and parks in Croatia. For each parasitoid assemblage the diversity indices were calculated: Domination index, Shannon's diversity index H and evenness of species E. Cluster analyses were used to compare the similarities of parasitoid assemblages. A total of 28 taxa of parasitoids from the superfamily Chalcidoidea and 4 taxa from the superfamily of Ichneumonoidea have been found. The majority of parasitoid species found were generalist species on other leaf miner species from Lepidoptera. P. roboris/P. quercifoliella have the most diverse parasitoid assemblage (the highest H value) followed by T. ekebladella. Oaks support the rich fauna of taxonomically and ecologically similar leaf miner species and free exchange of parasitoids is enabled among them. All the parasitoid species found on these leafminers are generalist. They also have the highest E value because they lack specific monophagous parasitoid species. P. klemannella has lower diversity indices H and E because of the dominance of specific parasitoids from the family Encyrtidae. P. platani has two dominant parasitoid species Minotetrastichus platanellus and Pediobius saulius. The dendrogram shows that P. roboris/P. quercifoliella, P. robiniella, P. leucographella, Pa. robiniella and T. ekebladella have similar parasitoid assemblages. Very similar are T. ekebladella and Pa. robiniella, both host species grow on the same sites together (oak and black locust) and generalists can search for similar mines: white upper surface leaf mines. The greater linkage distance between P. klemannella and P. platani can be explained with the dominance of specific monophagous parasitoid species in the assemblage. The similarities between parasitoid assemblages of native (P. roboris/P. quercifoliella, T. ekebladella) and alien (P. leucographella, P. robiniella, Pa. robiniella, C. ohridella) leaf miner species show that the native generalist parasitoids have adapted to new hosts. Ten species of parasitoids have been found on C. ohridella, with P. saulius and Minotetrastichus frontalis as the dominant species. The invasive leaf miner species in Croatia have recruited a parasitoid community similar to the native leaf miner species and that this process has occurred quite rapidly.