Parasitoids and fungal pathogens of Phyllonorycter issikii (Kumata, 1963) from Bulgaria

Abstract

The lime leaf miner, Phyllonorycter issikii, is a moth species native to East Asia, which recently invaded considerable part of Europe. A study on the natural enemies of this invasive species was conducted in Bulgaria. Tilia cordata leaves infested with the lime leaf miner were collected in 2015 and 2016 in two public parks in Sofia. A total of eleven eulophid parasitoids (Hymenoptera: Eulophidae) belonging to three subfamilies -Entedoninae, Eulophinae and Tetrastichinae, and one braconid species (Hymenoptera: Braconidae) were recorded. In addition, one unidentified ichneumonid species was reared. Minotetrastichus platanellus was the most abundant species in the samples comprising 76.88% of the parasitoids reared from collected immature and pupal stages of Ph. issikii. It is followed by Sympiesis gordius (6.53%) and S. sericeicornis (6.03%). Three new host-parasitoid associations were established. The entomopathogenic fungi Beuveria bassiana and Metarhizium anisopliae (Hypocreales) were isolated for the first time from cadavers of Ph. issikii larvae and pupae. Based on the presented observation we hypothesized that the lime leaf miner can produce three generations in Bulgaria.

The Hymenopterous Parasitoids of the Lime Leaf Miner Phyllonorycter issikii (Kumata) (Lepidoptera: Gracillariidae) from Its Native and Invaded Regions in Asian Russia

“…Prior to our research, the relationship of A. cilla and C. braconius with Ph. issikii was initially identified in Hungary [29,30]. Moreover, the eulophid Pleurotroppopsis japonica known to parasitize on Ph.…”

“…It is important to stress that the parasitoids of the family Braconidae were hardly reared from Phyllonorycter issikii. In the following sources [9,21,23,25,29,30], a few braconids were indicated to be trophically linked with Ph. issikii: Colastes braconius Haliday, 1833 (subfamily Exothecinae) [25,30], Dolichogenidea dilecta (Haliday, 1834), Pholetesor circumscriptus (Nees, 1834), Ph.…”

“…In the following sources [9,21,23,25,29,30], a few braconids were indicated to be trophically linked with Ph. issikii: Colastes braconius Haliday, 1833 (subfamily Exothecinae) [25,30], Dolichogenidea dilecta (Haliday, 1834), Pholetesor circumscriptus (Nees, 1834), Ph. exiguus (Haliday, 1834), Pholetesor sp.…”

“…This species was already recorded as the parasitoid of Ph. issikii in Slovakia [25] and Bulgaria [30].…”

Invasive alien forest insect species in south-eastern Romania

“…The data collected in 2017 provide the first reports of this species in south-eastern Romania. However, given that the spread of the species in Europe took place from east to west with a speed of at least 110 km/year (Šefrová, 2002) or even 200 km/year (Rodeland, 2007) and that it had already arrived near Sofia, Bulgaria in 2006 (Toshova et al, 2018), it is very likely that it was present in the southern part of Romania for many years without being detected. Even during the search in 2017, it was found at only two observation points because its mines are mostly found on the lower branches or on the undergrowth and in the inner part of the crown (Šefrová, 2002;Ermolaev and Zorin, 2011b) and do not cause a change in colour or premature drying of leaves (Kovács et al, 2006); consequently, the presence of the insect is not apparent.…”