Lisne buhe (Hemiptera: Sternorrhyncha: Psylloidea) sitni su, često nezamjetni kukci, koji predstavljaju neizostavnu komponentu mnogih ekosustava. Do danas je opisano oko 4000 vrsta, rasprostranjenih na cijelom svijetu, pri čemu im je raznolikost najveća u tropskim i suptropskim područjima. Lisne buhe isključivo su fitofagni, uglavnom monofagni ili oligofagni, kukci. Za ishranu preferiraju mladi biljni porast, rjeđe odrvenjele ili podzemne biljne dijelove. Zbog činjenice da se samo manji broj vrsta ubraja u važne poljoprivredne štetnike, lisne buhe najslabije su poznata natporodica unutar podreda Sternorrhyncha. Većina za poljoprivredu gospodarski važnih vrsta javlja se na višegodišnjim drvenastim voćnim kulturama i ukrasnom drveću i grmlju, rjeđe na zeljastim povrtnim vrstama. Vrste poznate kao gospodarski štetnici na biljkama uzrokuju izravne i neizravne štete. Izravne štete uzrokuju ličinke i odrasli stadiji sisanjem biljnih sokova dok su neizravne štete posljedica prenošenja biljkama vrlo štetnih unutarstaničnih fitopatogenih bakterija ili lučenja medne rose, na koju se posljedično naseljavaju gljivice čađavice i smanjuju fotosintetsku aktivnost zelenih biljnih dijelova.
Cilj ovog rada bio je sastaviti cjeloviti popis vrsta („check“ listu) lisnih buha u Hrvatskoj, temeljen na detaljnom pregledu dostupne literature i rezultatima vlastitog faunističkog istraživanja, utvrditi potencijalno prisustvo karantenskih vrsta Diaphorina citri Kuwayama, 1908, Trioza erytreae (Del Guercio, 1918) i Bactericera cockerelli (Šulc, 1909) te utvrditi prisutnost, brojnost i rasprostranjenost invazivnih vrsta lisnih buha, uključujući vrste ranije zabilježene na području Hrvatske. Tijekom istraživanja pregledani su svi dostupni literaturni izvori, a terenska i laboratorijska istraživanja obuhvaćala su prikupljanje uzoraka, obradu uzoraka pod binokularnom lupom, izradu makroskopskih suhih preparata imaga, izradu trajnih mikroskopskih preparata, identifikaciju vrsta pod svjetlosnim mikroskopom uz korištenje literature te označavanje, sušenje i pohranjivanje trajnih preparata. Pretraživanje literaturnih podataka obuhvatilo je razdoblje od 1894. do 2021. godine te su utvrđeni navodi za 77 vrsta lisnih buha. Pročišćeno je 29 sinonima vrsta prema važećoj nomenklaturi. Terensko i laboratorijsko istraživanje provedeno je u razdoblju od 2015. do 2021. godine, u 20 županija na području Hrvatske, prilikom čega su prikupljena 503 uzorka entomofaune, biljnog materijala i žutih ljepljivih ploča. Izrađeno je 455 trajnih mikroskopskih preparata ličinki i genitalija odraslih stadija lisnih buha te 172 suha makroskopska preparata imaga. U uzorcima je identificirana 51 vrsta. 18 vrsta novo je za faunu Hrvatske, od čega su četiri vrste stranog podrijetla. Novoutvrđene vrste pripadaju u 4 porodice (Aphalaridae, Liviidae, Psyllidae i Triozidae), odnosno 12 rodova. Rodovi Colposcenia Enderlein, 1929, Rhodochlanis Loginova, 1964, Glycaspis Taylor, 1960 i Arytaina Foerster, 1848 novi su za faunu Hrvatske. Popis („check“ lista) lisnih buha Hrvatske, sastavljena objedinjavanjem pouzdanih literaturnih podataka i rezultata vlastitih faunističkih istraživanja, trenutno obuhvaća 81 vrstu iz 6 porodica i 29 rodova. Niti u jednom analiziranom uzorku nisu zabilježene karantenske vrste lisnih buha. Invazivne vrste Ctenarytaina eucalypti (Maskell, 1890), Acizzia jamatonica (Kuwayama, 1908) i Cacopsylla fulguralis (Kuwayama, 1908), čije je prisustvo ranije utvrđeno na području Hrvatske, zabilježene su ponovno tijekom ovog istraživanja i utvrđena je njihova rasprostranjenost. Ovaj rad značajan je prilog znanosti u oblasti faune lisnih buha Republike Hrvatske. Izučavanje morfološke identifikacije kukaca i poznavanje vrsta prisutnih na određenom području neophodno je za sprječavanje nastanka većih gospodarskih šteta u poljoprivredi. Samo na temelju točne identifikacije vrsta te poznavanja njihove biologije i ekologije, moguće je provesti učinkovito i pravovremeno suzbijanje štetnih kukaca. Budući da tri karantenske vrste predstavljaju potencijalnu opasnost za agrumarstvo odnosno proizvodnju krumpira u Hrvatskoj, neophodno je nastaviti pratiti njihovu potencijalnu pojavu.
Psyllids or jumping plant-lice (Hemiptera: Sternorrhyncha: Psylloidea) are a relatively small group of phytophagous, predominantly monophagous and oligophagous, phloem-feeding insects. Due to their smally body size, ranging 1,5-4,5 mm, they often go unnoticed on their host plants. Together with aphids, scale insects and whiteflies they constitute the suborder Sternorrhyncha within the order Hemiptera. Since not many psyllid species are known as plant pests, they are the least known superfamily within the suborder, but have recently gained attention as vectors of some very harmful plant pathogens. The identification of species is often challenging, due to their great similarity, small size and a limited number of diagnostic morphological characters.
Some 4000 species have been described so far, classified in seven families, with a distribution throughout all major zoogeographical regions of the world, but showing greatest diversity in tropical and south temperate regions. Psyllid life cycle typically comprises of an egg stage, five larval instars (nymphs) and a sexually reproducing adult stage. Adult psyllids are characterised by the ability to jump, a trait from which their common name “jumping plant-lice” stems. Tropical and south temperate species are usually polyvoltine, with several overlapping generations per year, while north temperate species are generally univoltine, spawning one generation per year. Although relatively few species are known as serious pests, those that are, usually cause economically significant damages. Direct damages are caused by feeding of nymphs and adults on their host plants, which may result in chlorosis and necrosis of infested plant tissue, premature defoliation, stunted plant growth or wilting. Indirect damages are seen through transmission of harmful phytoplasma diseases and abundant excretion of excessive carbohydrates, an intake from sugar rich phloem content, in the form of honeydew. Honeydew is often subsequently infested with sooty moulds that decrease photosynthetic activity of leaves and, in ornamental plants, their decorative value. Nymphs are usually more destructive as they feed on young shoots and leaves rich in nitrogen compounds and in some species cause severe galling of plant tissue. Most psyllids feed on dicotyledonous angiosperms. Some, such as representatives of the genus Livia Latreille, 1802 or species Bactericera tremblayi Wagner, 1961 and Bactericera kratochvili Vondráček, 1957 are associated with monocotyledonous angiosperms (Juncus spp., Carex spp., Allium spp.), while only four species develop on conifers. However, conifers serve as shelter plants on which many species overwinter and are therefore often accidentally mistaken for host plants.
Alien terrestrial invertebrates represent one of the most numerous groups of organisms introduced into Europe. They are recognised as a great threat to biodiversity, as their introduction into Europe has increased in the last two decades. Arthropods, mostly insects, are the most dominant and represent for nearly 94% of all species within the group. At the order level, Hemipterans are the second most represented, accounting for 26% of all alien insects. Most alien insect species spread unintentionally through human activities, mainly by abundant international trade of their host plants, particularly woody ornamentals. Due to their small size, which makes them difficult to detect, Hemipteran species, including psyllids, seem particularly prone to such spread. In combination with global warming, many insect species from subtropical and tropical areas domesticate easily in Europe, particularly in southern regions. The same trend has been noticed in Croatia. Prior to this research, three alien species from superfamily Psylloidea were already reported from Croatia.
Of special interest for Europe are alien species regulated under Regulation (EU) 2016/2031, called quarantine pests. These species are absent from Europe, or are present very locally, and present a significant threat to European crop production. Three psyllid species, Diaphorina citri Kuwayama, 1908, Trioza erytreae (Del Guercio, 1918) and Bactericera cockerelli (Šulc, 1909) currently have such status under Commission implementing Regulation (EU) 2019/2072,
as vectors of very destructive plant diseases. D. citri and T. erytreae are vectors of destructive citrus pathogens, while B. cockerelli transmits pathogen of solanaceous crops. T. erytreae is the only species currently present in Europe, with distribution recorded in Spain and Portugal.
Fauna has been researched and check-lists have been published for all other superfamilies within Sternorrhyncha in Croatia, which makes psyllids the only remaining group that hasn't been explored. Therefore, three main aims for this study were set. First, to compile a check-list of psyllid species present in Croatia, based on distributional data available in the literature and the results from author's field research. Second, to establish the presence and distribution of new, as well as previously recorded alien species, and last, to establish potential presence of quarantine psyllid species.
In order to compile a check-list, available literature covering period 1894-2021 was browsed and only records that unambiguously referred to the territory of modern-day Croatia were included on the list. Field survey of psyllid fauna was carried out in the period 2015-2021 on agricultural crops, in private gardens, commercial garden centres, on public greenery, in forests and nurseries, on wild and cultivated flora all across Croatia. Survey included visual inspections of host plants and collection of infested leaves with nymphs into a transparent plastic bags. Adults were collected with entomological fine mesh sweeping net or by beating of branches on a white tray. Entomofauna was subsequently collected with a mouth aspirator. In certain occasions, yellow stick traps were used. Samples of adult psyllids were deposited into 70% ethanol and brought into laboratory for identification. Late-instar nymphs and adults' genitalia were slide-mounted and identified to the species level under stereo and optical microscopes. Identification of the collected species was based on morphological characteristics of adult males i. e. their highly specific genitalia, slide-mounted in a combination of Canada balsam and 1/3 benzyl-alcohol. Only one species, Psylla foersteri Flor, 1861, was identified based on morphological characteristics of adult females and two species, Trioza ilicina (De Stefani Perez, 1901) and Trioza soniae Rapisarda, 1994 based on morphological characteristics of late-instar nymphs. Slide-mounted genitalia and late-instar nymphs were compared to descriptions, illustrations and keys available in the literature to identify the species. All slide-mounts were labelled with data relevant for a faunistic entry and deposited in the entomological collection of Centre for plant protection, Zagreb.
According to the available literature data, 77 psyllid species were previously recorded from the territory of modern-day Croatia, for which 29 synonyms were clarified in accordance with the latest systematic classification.
During faunistic research on psyllids in Croatia 503 samples of entomofauna, plant material and yellow sticky traps were collected, out of which 455 permanent slides of larvae and adult's genitalia and 172 adult voucher specimens were prepared. 51 psyllid species were subsequently identified, 18 of them new for psyllid fauna of Croatia. Species new for Croatian fauna are: Colposcenia traciana (Klimaszewski, 1970), Rhodochlanis bicolor (Scott, 1880), Glycaspis brimblecombei Moore, 1964, Psyllopsis discrepans (Flor, 1861), Acizzia acaciaebaileyanae (Froggatt, 1901), Acizzia uncatoides (Ferris & Klyver, 1932), Diaphorina chobauti Puton, 1898, Arytaina genistae (Latreille, 1805), Cacopsylla brunneipennis (Edwards, 1896), Cacopsylla myrthi (Puton, 1876), Cacopsylla pulchella (Löw, 1877), Cacopsylla saliceti (Foerster, 1848), Livilla variegata (Löw, 1881), P. foersteri, Psylla hartigii Flor, 1861, Bactericera crithmi (Löw, 1880), T. ilicina and T. soniae. Newly recorded species belong to 12 genera within families Aphalaridae, Liviidae, Psyllidae and Triozidae. Four genera, Colposcenia Enderlein, 1929, Rhodochlanis Loginova, 1964, Glycaspis Taylor, 1960 and Arytaina Foerster, 1848, are new for Croatian entomofauna.
Currently, the check-list of psyllids in Croatia comprises 81 species belonging to 6 families and 29 genera. Ctenarytaina eucalypti (Maskell, 1890), Acizzia jamatonica (Kuwayama, 1908) and Cacopsylla fulguralis (Kuwayama, 1908), alien species previously recorded in Croatia, were recorded again during this research and their distribution was established. Additionally, four
new alien species were discovered and their presence published in relevant journals. Quarantine psyllid species were not identified in any of collected samples and can be declared as absent from the Croatian territory.
This research gives a first thorough insight into psyllid fauna of Croatia. The three quaratine species would present a threat to citrus and potato production, should they be introduced into Croatia. Therefore, the monitoring of their potential presence is of high importance. Only accurate identification of species allows for a timely and efficient control against plant pests. Therefore, morphological identification and cataloguing of present species serve as a foundation for successful control of species that represent threat to agricultural production.