Invasive phyllophagous insects in Ukraine

Abstract

The biological invasion of non-native organisms can cause significant economic losses as well as large-scale damage to natural ecosystems. Among the invasive insects, the spread of alien phyllophagous insects feeding on the plant leaves is becoming increasingly important. The reconnaissance survey of green areas and forests in the Lviv, Transcarpathian, and Ternopil regions of Ukraine, aiming to identify the invasive species, was conducted in 2017-2019. The symptom/damaged part and a close-up of any feeding of phyllophagous insects including larvae, adults, pupae, or eggs were collected and labelled using general recommendation for collecting arthropod pests. Accurate identification and specimen affiliation were carried out based on microscopic analyses, available guides, or online resources. Fall webworm (Hyphantria cunea) is the species of internal quarantine in Ukraine that has been successfully introduced and spread in forests, gardens, and green plantations; it is widespread across Ukraine. The larva of false acacia sawfly (Nematus tibialis) was rarely found feeding on the leaves of black locust with no significant threat to the species' trees. In 2014, box tree moth (Cydalima perspectalis) penetrated into the territory of Transcarpathia from Hungary. Nowadays, this invasive species is spread in all green areas of big cities such as Lviv, Odesa, Kyiv, Kharkiv, Mykolaiv, Dnipro, and in the Transcarpathian region causing a huge foliage loss to boxwood plants. The invasive elm zigzag sawfly (Aproceros leucopoda), causing local damage to Ulmus trees, was recorded in 2010. The horse-chestnut leaf-mining moth (Cameraria ohridella) is still a leader among the invasive leaf miners in urban plantations. It has spread almost all over the country and causes significant infestation of horse-chestnut leaves every year, even if there is no evidence that moth damage leads to tree death. An increasing importance of damages caused by invasive leaf miners feeding in the mines of the leaves of lindens (lime leaf mine Phyllonorycter issikii), planes (plane leaf miner Phyllonorycter platani) and locusts (leaf blotch miner moth Macrosaccus robiniella, locust digitate leafminer Parectopa robinella) was also recorded. Recently, the strong damage of sycamore lace bug (Corythucha ciliata), a new invasive species that belongs to the piercing and sucking insects feeding on the lower leaf side and sucking sap was detected in the Transcarpathian and Kherson regions of Ukraine. Since 2018, this invasive pest has penetrated into the urban green areas of Lviv City. The citrus flatid planthopper (Metcalfa pruinosa), another invasive species, was recorded in Transcarpathian and Odessa regions. It is considered as a very important invasive species due to its gregarious behavior and mobility. The brown marmorated stink bug (Halyomorpha halys) was also found on agricultural crops in the Odessa region. Newly detected invasive species have all the prerequisites for further distribution into the forests and green plantations across Ukraine. Lilac leafhopper (Igutettix oculatus) was identified as an invasive pest of Syringa spp., Ligustrum spp. and Fraxinus spp. in the green urban areas of Lviv City in 2019. The importance of invasive aphids such as Prociphilus fraxinifolii, Appendiseta robiniae, Aphis craccivora, A. nerii, Illinoia lambersi has also increased especially in green urban areas between 2018 and 2019. Black locust gall midge Obolodіplosіs robіnіae was also found widely distributed. However, it does not have currently any significant damaging effect on black locust trees. Newly recorded identification of invasive phyllophagous insects may amplify the concern on the increasing threat to the leaves of forests and green plantations. Based on personal observations and literature analyses, we strongly believe that the main pathway of invasive insects’ spread in Ukraine is the trade of planting material and ornamental plants. We have found that the use of chemical and mechanical methods to control the spread of invasive phyllophagous insects does not provide a sufficiently long-lasting effect. According to the research review, the natural control of invasive phyllophagous insects is possible only when an effective parasitic complex occurs. This complex, in combination with other measures, can become the basis of the integrated protection methods for forests and green urban areas in the future.

Keywords

• phyllophagous insects
• invasive species
• pathway
• forests
• green urban areas