The oak lace bug (Corythucha arcuata) - a multiple threat on oak ecosystems G. Csóka, M. Paulin, Á. Mikó, C. Eötvös, C. Gáspár, A. Hirka NARIC Forest Research Institute, Department of Forest Protection, Mátrafüred, Hungary DETECTION AND CONTROL OF FOREST INVASIVE ALIEN SPECIES IN A DYNAMIC WORLD LIFE ARTEMIS Conference Ljubljana, Slovenija 25-28th September 2019 More new non-native species in the last 30 years than in the previous 110 years Numbers of newly detected non-native insects on woody-plants in Hungary since 1881. Nezara viridula (Africa) Halymorpha halis (Asia) Corythucha arcuata (North America) Non-native hemipterans from three continents A „rising star” in Europe Oak lace bug (Corythucha arcuata) Origin: North-America, where it is not considered significant pest. Known distribution OLB in Eurasia with the years of the first records Magnitude of the invasion in Europe: At least 100,000 ha severely infested oak forest in CE Europe. More than 1 million hectares including European part of Russia 2017 2017 2014 2016 2019 2013 2017 2015 2015 2019 2019 2017 2017 2013 2016 2015 2017 2015 2016 Presently known distribution in Hungary with the year of first record in the given county Different levels of C. arcuata infestation in Hungary (September 2019) Potential host range We checked 48 different oak species in 20 sentinel gardens in seven countries. Presence of OLB was recorded at 15 locations in five countries (Croatia, Hungary, Italy, Romania and Serbia). A total of 27 out of 48 oak species have been proven to be suitable OLB hosts. Of these 27, 15 were globally new host records for OLB. Almost all Eurasian deciduous oak species are suitable host! Q. Q. Q. Q. Q. Q. Q. Other Country Total (th ha) cerris ilex petraea pubescens pyrenaica robur suber oaks Austria 7 39 1 25 3 75 Albania 0 Bosnia-Hercegovina 300 300 Bulgaria 1,051 Croatia 29 153 294 570 121 1,167 France 700 1,651 1,390 1,990 94 5,825 Germany 1,130 Greece 1,430 Hungary 212 138 19 110 14 493 Italy 0 Macedonia 0 Poland 690 Portugal 331 737 67 1,135 Romania 1,130 Russia 3,000 Serbia 345 173 10 33 561 Slovakia 48 180 25 233 Slovenia 0 Spain 2,891 1,609 2,000* 6,500 Turkey 6,476 Ukraine 2,400 2,400 United Kingdom 219 Total: 33,315 Extent of oak forests in European countries Albania: Ejup CotaAustria: Gernot HochBosnia-Hercegovina: Mirza DautbašićBulgaria: Georgi Georgiev France: Rémy PetitGermany: Björn HoppeGreece: Dimitrios AvtzisItaly: Iris Bernardinelli Poland: Jacek Hilszczański Portugal: Manuela BrancoRomania:Constantin CiorneiSpain: Jose Luis Nieves-AldreySwitzerland: Beat ForsterUkraine: Valentina Meshkova Non-Quercus hosts records Occasional symptoms Frequent and/or mass symptoms Acer campestre Castanea sativa Betula pendula Prunus serotina Carpinus betulus Rubus caesius Corylus avellana Tilia cordata Corylus colurna Tilia platyphyllos Cotinus coggygria Fagus sylvatica Juglans regia Keria japonica Koelreuteria paniculata Lysimachia punctata Prunus serratula Prunus spinosa Robinia pseudoacacia Rosa canina Sorbus aria Sorbus torminalis Ulmus glabra Ulmus minor Direct impact: Early discoloration and desiccation of the foliage (sometimes already in late June) Indirect impacts: Oak health? Vectoring pathogens? Growth? Acorn crop? Human – OLB interactions? Oak related herbivore diversity? Pedunculate oak Black locust Pedunculate oak Pedunculate oak Ash Black locust Ash Aerial image from Gyula (SE Hungary) Source: DALERD Co. Ltd. Ash Pedunculate oak Ash Pedunculate oak Ash Ash Pedunculate oak Pedunculate oak Ash Pedunculate oak Drone image from infested pedunculate oak stand Source: Mecsek Forestry Co. Ltd. Photosynthetic acivity of severely infested oaks reduced by 59%, the transpiration activity by 22%. Nikolić, N., Pilipović, A., Drekić, M., Kojić, D., Poljaković-Pajnik, L., Orlović, S. & Arsenov, D. (2019): Physiological responses of pedunculate oak (Quercus robur L.) to Corythucha arcuata (Say, 1832) attack. Archives of Biological Sciences, 71, 167–176. Similar results in Hungary (unpublished). Decreasing fecundity of oaks - Less and smaller acorns - Early acorn abscission - Less frequent masting years? Impacts on oak regeneration and wildlife??? Blood-sucking beasts in my bedroom! The citizen complains begin... Exclusively one oak species ~650 species 11% Oaks belonging to one section of oaks 15% Polyphagous 44% Oak specialists 47% (˃300 species) Oaks 21% Species belonging to Fagales Species belonging to 4% Fagaceae 5% Degree of host specificity of oak feeding insects in Hungary Leaves Flowers Acorns Roots 66.4% Stem (˃430 species) Branches, shoots Buds Distribution of oak feeding herbivore insects by feeding locations f a j 400 380 350 335 303 300 283 251 H o m o p t e r a 250 C o l e o p t e r a 200 172 Hym enoptera 150 Lepidoptera 100 89 50 11 11 0 III. I V . V. VI.VII.VIII.IX. X. XI. hónap Number of herbivore insect species potentially feeding on oaks by months (Csóka 1994) Larvae of late season oak specialist folivores (Harpya milhauseri – left; Drymnoia querna – center; Apoda limacodes - rigth) starve and die on severely infested leaves. Asexual generations of cynipid gall wasps suffer high mortality on severely infested leaves (asexual generation of Cynips quercusfolii). No „serious” natural enemy has been found so far! Summary WhatWhat wewe alreadyalready know:know: OLBOLB showedshowed a arapid rapid spread spread and and outbreaks outbreaks in the in last the 5 lastyears 5 -in6 yearsmany inSE manyEuropean SE Europeancountries. Both countries accelerated. It m ayspread have and 2- 3population generations increase per yearwere likely helped by the mild winters an the dry and hot summers. in SE Europe. It may have up to three generations per year in SE Europe. AllThe majorrelatively Eurasian cold winter deciduous of 2016/2017 oaks did(both not incause section high overwinteringCerris and sectionmortality. Quercus) seem to be prime hosts. So at least 30 million hectaresAll major ofEurasian oak forests oaks (both provide in section suitable Cerris hosts and for section OLB inQuercus) Europe. seem Spreadsprime hosts. as Sotypical at least „ 30hitchiker million hectares”, first appears of oak forests along provide main suitable roads hostsand citiesfor OLB.. No way to stop the spread. Spreads as typical „hitchiker”, first appears along main roads and cities. SevereNo way toattack stop the may spread. cause mass discoloration and desiccation of leavesSevere attackby late may June. cause mass discolouration of leaves by early July. SevereNo natural infestation enemies hasseem negative to have effectsconsiderable on oaks regulation’ fecundity. potential in the invaded area in this phase. It has proven negative impact on some oak specialist herbivores. No natural enemies seem to have considerable potential of regulation in the invaded area in this phase. What we still do not know, but should urgently know: Will the climate restrict the further spread to North and West? Where and when? Will the damage become as „chronic” as damage by C. ciliata on Platanus? Direct and indirect impacts of long term damage on tree growth and health? Impact on survival of seedlings and young stands? Can C. arcuata act as vector of some oak pathogen? How much and how serious damage should be expected? Long term impact on the extremely species rich oak herbvivore communities? What can we do? Ostrich policy? Praying? More alcohol to forget the problem? Will „Mother Nature” alone save our oaks and oak-related diversity? ALARM, RESEARCH NEEDED! Participants of the EUPHRESCO OLBIE kick off meeting 24th July, 2019 – Bogdása, Hungary Thanks for your attention! .