A new tritrophic association

Simple SummaryThe oak lace bug (OLB), Corythucha arcuata, is a cell sap-sucking insect that is native to North America but has spread rapidly in European countries as an invasive pest. The main hosts are oaks, but it can develop on other forest species as well. Its occurrence is worrying in terms of the cumulative impacts that it could have on forests, as well as the molestation of imago in cities that have been frequently reported. Since the pest is still a new element of a biocoenosis, there is a lack of research on its natural enemies and competitors that could form a potential foundation for biological control strategies. Although there have been reports that lace bugs are quite susceptible to a fungal diseases amid more humid conditions, to date, none of the pathogenic fungi found on OLBs under natural conditions were identified in the literature. In this study, we provide evidence of four entomopathogenic fungi: Beauveria pseudobassiana, Lecanicillium pissodis, Akanthomyces attenuatus and Samsoniella alboaurantium that could present a potential as biological control agents against OLBs.The oak lace bug (OLB), Corythucha arcuata (Hemiptera: Tingidae), was first identified as an invasive pest in Europe in northern Italy in 2000 and since then it has spread rapidly, attacking large forested areas in European countries. The OLB is a cell sap-sucking insect that is native to North America, with Quercus spp. as its main host. Its rapid expansion, successful establishment in invaded countries, and observations of more damage to hosts compared to native areas are most likely due to a lack of natural enemies, pathogens and competitors. In its native area, various natural enemies of OLBs have been identified; however, little is known about the occurrence and impact of OLB pathogens. None of the pathogenic fungi found on OLBs in natural conditions have been identified until now. In this study, we provide evidence of four entomopathogenic fungi that are naturally occurring on invasive OLBs found in infested pedunculate oak forests in eastern Croatia. On the basis of their morphology and multilocus molecular phylogeny, the fungi were identified as Beauveria pseudobassiana, Lecanicillium pissodis, Akanthomyces attenuatus and Samsoniella alboaurantium. The sequences generated for this study are available from GenBank under the accession numbers MT004817-MT004820, MT004833-MT004835, MT027501-MT27510, and MT001936-MT0011943. These pathogenic species could facilitate biological control strategies against OLBs.

Insect herbivores co-occurring on the same host plant interact in various ways. In particular, early-season insect herbivory triggers a wide range of plant responses that can determine the performance of herbivores colonizing the plant later in the course of the season. But the strength and direction of such effects are debated, and virtually unknown in the case of novel interactions involving exotic insects in their introduction range. We conducted an observational field study in SW France, a region recently invaded by the Oak Lace Bug (OLB, Corythucha arcuata Say). We measured early chewing damage and subsequent OLB damage in four oak species (Quercus robur, Q. pubescens, Q. cerris and Q. ilex). We set up a complementary non-choice experiment in the laboratory, feeding OLB with leaves with or without prior herbivory. The four oak species differed in their sensitivity to OLB damage, Q. ilex being broadly resistant. Prior herbivory promoted OLB damage in the laboratory experiment, but not in the field. However, prior herbivory did not alter the rank of oak resistance to the OLB. Our results suggest possible synergistic effects between spring defoliators and the OLB. This study brings insight into herbivore-herbivore interactions and their possible implications for forest management.

The oak lace bug (Corythucha arcuata Say) was introduced to Europe from North America in 2000 and was first recorded in Serbia in 2013. It is a very serious oak pest which has harmful effect in both adult and nymph stages of the insect that feeds by sucking the sap on the lower (abaxial) leaf side. As this is a relatively new pest in our country, the possibility of its control by applying insecticides was tested during 2021. The paper presents the test results of three insecticidal active substances: deltamethrin, flonicamid and acetamiprid for the control of oak lace bugs. The insecticide flonicamid did not show sufficient efficacy in the suppression of the oak lace bug, while deltamethrin and acetamiprid have high efficiency for the suppression of the adults and nymphs of the oak lace bug, which recommended them for this purpose.

Corythucha arcuata (Say) (Hemiptera: Tingidae) is a pest of oaks that is highly distributed in several regions of the world, including North America, the Balkan Peninsula, Europe, and Turkey. In the present study, ten entomopathogenic fungi belonging to four different genera (Metarhizium (×4), Beauveria (×4), Isaria (×1), and Myriodontium (×1)) were tested against nymphs and adults of C. arcuata under laboratory conditions. Based on the initial screening studies, it was shown that all isolates were able to infect both nymph and adult individuals of the pest after application of 1 × 10 7 mL -1 conidial concentration. Among the tested isolates, Beauveria bassiana KTU-24 caused the highest mortality against both nymphs and adults within 14 days, with 80% and 90% mortality, respectively. This isolate also produced the highest mycosis values on both nymphs and adults, with 77% and 83% mycosis, respectively. Therefore, this isolate (B. bassiana KTU-24) was selected for concentration-mortality response tests for further characterization. The concentration- mortality response tests showed that the conidial concentrations of 1 × 10 8 and 1 × 10 9 mL -1 of B. bassiana KTU-24 produced 100% mortality against nymphs and the conidial concentration of 1 × 10 9 mL -1 of this isolate caused 100% mortality against adults. Based on probit analysis, the LC 50 values of the isolate B. bassiana KTU-24 were calculated as 1.17 × 10 7 and 6.44 × 10 6 conidia mL -1 against nymphs and adults, respectively. This study indicates that B. bassiana KTU-24 has a significant potential for further investigation as biological control agent against C. arcuata.

In addition to the classic biotic and abiotic factors that have disrupted the health of forests throughout history, lately, the balance of forest ecosystems has been disturbed by different phenomena such as climate change, pollution, and, especially, biological invasions of invasive alien species. One of the alien species that has invaded Europe relatively quickly is an insect species of North American origin, the oak lace bug (Corythucha arcuata Say, 1832 Heteroptera: Tingidae). In the context of the rapid spread of infestations and the severity of attacks on oak trees in infested forests, this paper aims to assess measures to manage this species in the future. Namely, the effect of aerial chemical treatments on oak lace bug has been investigated with two influencing factors: the mode of insecticide action (contact and systemic) and the treatment volume (low volume and ultra-low volume). The experiment was conducted in two forests over a total area of 350 hectares. The results show that the reduction of the nymph population varied from 91% to 96%. However, the residual population was sufficient to allow differentiated re-infestations over time, more quickly after contact insecticide sprays (22 days after treatment) and slowly after systemic insecticide sprays (more than a month after treatment). This re-infestation time difference had implications on attack intensity as well, with stronger leaf discoloration observed in areas treated with a contact insecticide compared with those treated with a systemic insecticide.

Oak lace bug (OLB) Corythucha arcuata (Say, 1832) (Heteroptera: Tingidae) is native to North America. In 2000 it got to Italy and has spread for recent 20 years in many countries in Europe. In 2017 OLB first registered in Kherson region of Ukraine. The aim of the research was to summarize the first data on oak lace bug spread in Ukraine. The studies were carried out in 2020 at 31 sample plots in the south-western part of the Kherson region (46°10 ' to 47°21' N, 32°10' to 33°05' E). The sample plots were located in forest stands, shelterbelts, and oaks in cities. The age of inspected stands is from 25 to 250 years old. The presence of oak lace bug and the threat to oak trees was assessed by a point system: 0 – OLB is absent; 1 – single, one egg mass per whole plot; 2 – rare, below 10% of trees damaged; 3 – common, OLB presents not in all trees, foliage damage up to 50%; 4 – widespread, OLB presents in all trees, foliage damage up to 100%. The weighted average score of OLB presence was evaluated for different groups of stands and some of their characteristics. The specimens of OLB and the traces of their vital activity were found at 19 sample plots (61,3%). At 51.6% of sample plots examined the OLB was common or widespread. The pest is widespread at 8 sample plots, including oaks in cities Kherson, Oleshki, and Hola Prystan, Doslidne forestry of the Steppe branch of Ukrainian Research Institute of Forestry & Forest Melioration named after G.M. Vysotsky (URIFFM) and Burkutske forestry of the Velikokopanske Forest & Hunting Enterprise. Mean OLB score is higher in forests than in shelterbelts and has a trend to increase with oak age. The highest OLB infestation was assessed in the sample plots neighbouring city streets and forest roads and in the sample plots near the waterway. The proportion of SP with common and widespread OLB from all inhabited plots near city streets, forest roads, and waterways exceeds 80%. The data obtained can be considered preliminary, since the reproduction, distribution, and settlement of the oak lace bug in the territory of the Kherson region began only 2 years ago.

Provides an overview of Sycamore lace bug (Corythucha ciliata Say) and Oak lace bug (C. arcuata Say) based on literature data and monitoring during the period 2018-2022. The species have been present in insect fauna of Serbia over the past fifty years and ten years, respectively. Lace bugs are significant pests of sycamore and oak trees. Their damage manifests itself as premature desiccation and drop of leaf mass (premature defoliation), reducing air quality benefits of trees in urban areas and diminishing aesthetic function. Additionally, tissue injury and loss of nutrients can affect longevity of mature trees and reduce woody mass yield. Presents information on origin and geographic range, biology, damage and control of lace bugs.

This scientific paper examines the impact of climate change on the spread and survival of the invasive species Corythucha arcuata Say, 1832 (oak lace bug, or OLB) in Romania. The OLB is native to the Eastern USA and Canada, and in its native habitat, it coexists with minimal impact to the preferred host plant species Quercus. However, in Europe, the OLB in high density causes early defoliation, slowing tree growth. As Quercus spp. is a keystone species, the impact of the OLB on European forests is significant. This paper aims to address several gaps in knowledge about the OLB by presenting findings from a study conducted by the Lucian Blaga University of Sibiu (ULBS) in Romania. The study identified the species’ chronology of spread, ecology, ethology and biology of the species, in addition to foliage classification to determine the extent of attack. The study found a direct link between the temperature and the speed of the generational lifecycle. The findings support the thesis that climate change is enabling the healthy, rapid density growth of OLB, which is a danger to the Quercus spp. Further research is needed in the area of the thermal tolerance of the OLB, and the research conducted by the ULBS represents the first documented research into the thermal constant of the insect. The paper concludes that further research must be in the direction to understand how and where these insects survive during winter to find future management measures and identify chemical or biological methods as solutions to eradicate and stop the expansion of the invasion of the OLB, and the potential consequences for the Quercus sp.

Oak lace bug (Corythucha arcuata) has continuously spread through Europe since its appearance in 2000, and it has become a dangerous pest of Quercus species in most countries. Despite of its high abundance in the surrounding countries it was found in West Ukraine only in 2020. During our investigation carried out in 2020 OLB was detected in all studied large forest patches of the Ukrainian part of the Carpathian Lowland. These were one of the newest distribution data from Ukraine after its appearance in the far coast of Black See near Yalta (South Ukraine). OLB most live on Q. robur and Q. petraea but in an orchard located near an infested forest patch we found infested sweet cherry (P. avium) trees, which is a new, formerly not mentioned cultivated host of the pest.

Oak lace bug – Corythucha arcuata (Say, 1832) (Hemiptera: Tingidae) is a North American species that has been introduced to Europe and Asia, where it became a serious oak pest. As little is known about its behavior, we conducted a study in which we tested the preference and performance of the oak lace bug for different oak species and the influence of powdery mildew and CO2 on the behavior of the oak lace bug. Four of the most represented oak species in Serbia (Hungarian, pedunculate, sessile, and Turkey oak) were used for testing the preference and performance of the oak lace bug, and the influence of oak powdery mildew on the behavior of the oak lace bug. The influence of CO2 on the behavior of the oak lace bug was tested on pedunculate oak. The results of this study have shown that there are differences in preference and performance of the oak lace bug between the analyzed oak species; there are significant differences in the oak lace bug host preference in the laboratory and in field conditions; Hungarian oak is most threatened by the oak lace bug, as the oak lace bug performs best on this species and preferers this species in field conditions; the oak powdery mildew and oak lace bug are in an antagonistic relationship; and that the changes in the leaves caused by the expected increase in CO2 concentration in the future will probably not influence the feeding behavior of the oak lace bug adults.

Forest ecosystems provide invaluable ecological, economic, and social benefits, making them essential for global well-being. However, these ecosystems face various threats, including biological invasions by alien species. Among these, the oak lace bug (OLB), an invasive North American insect, has rapidly spread in Europe, impacting oak forests and raising concerns about its adaptation to new environments. OLB feeds on the undersides of oak leaves, extracting sap and causing chlorotic discoloration. Severe infestations lead to premature defoliation, increased susceptibility to diseases or pests and can also result in a substantial reduction in photosynthesis activity. This study aims to analyse OLB’s invasive behaviour in Romanian forest ecosystems, with a specific focus on the differences between thermophilous and mesophilous oak forests. The analysis covers 6 years of data and reveals critical insights. In the initial 4 years, OLB predominantly inhabited the extracarpathian regions of Romania, with concentrated presence in the southern, western, and northwestern areas. Forest ecosystems mainly affected between 2017 and 2020 were characterized by thermophilous oak forests in southern and western regions. However, in the last 2 years (2021–2022), OLB presence increased, particularly in lowland ecosystems, albeit with reduced damage intensity. The analysis also unveiled an adaptation and expansion of OLB in mesophilous forest ecosystems. Climatic factors, specifically temperature and precipitation, significantly influenced OLB’s behaviour, points with severe attacks exhibiting specific climatic conditions. In summary, this study provides crucial insights into OLB’s behaviour, emphasizing the role of climatic and environmental factors in its invasive tendencies.

Oak lace bug - Corythucha arcuata (Say, 1832) (Hemiptera: Tingidae) is a North American species that has been introduced to Europe and Asia, where it became a serious oak pest. As little is known about its behavior, we conducted a study in which we tested the preference and performance of the oak lace bug for different oak species and the influence of powdery mildew and CO2 on the behavior of the oak lace bug. Four of the most represented oak species in Serbia (Hungarian, pedunculate, sessile, and Turkey oak) were used for testing the preference and performance of the oak lace bug, and the influence of oak powdery mildew on the behavior of the oak lace bug. The influence of CO2 on the behavior of the oak lace bug was tested on pedunculate oak. The results of this study have shown that there are differences in preference and performance of the oak lace bug between the analyzed oak species; there are significant differences in the oak lace bug host preference in the laboratory and in field conditions; Hungarian oak is most threatened by the oak lace bug, as the oak lace bug performs best on this species and preferers this species in field conditions; the oak powdery mildew and oak lace bug are in an antagonistic relationship; and that the changes in the leaves caused by the expected increase in CO2 concentration in the future will probably not influence the feeding behavior of the oak lace bug adults.

Studying the genetics of harmful insects populations is of great importance in understanding the migratory processes of species, especially invasive ones, and the fl ow of genes between populations. In this regard, one of the priorities of the genetics of arthropod populations is to assess the genetic similarity of individuals, genetic diversity, and DNApolymorphism. Universal RAPD-primers (OPA07, OPA09 and OPA18) for lace bugs (Tingidae family) have been revealed. In order to study DNA-polymorphism and the genetic diversity of lace bugs using selected primers, a comparative PCR-analysis of four species of bugs of this family (Corythucha arcuata Say, Corythucha ciliata Say, Stephanitis pyri F., Monosteira unicostata Mulsant et Rey) was carried out. It was shown that the species Monosteara unicostata diff ered from the others in the lowest level of DNA polymorphism and genetic diversity. The high values of DNA polymorphism and genetic diversity of the other three species indicate a high migratory ability of these insect species and a signifi cant intraspecifi c gene drift. In the research process, clustering of lace bugs species based on the data obtained using RAPD-markers was carried out in order to determine their genetic relationship. Cluster analysis of the data was performed by the UPGMA-method using the Popgene program. We found out that the genetically closest species were the species of the genus Corythucha, and the most distant from others was the species Monosteira unicostata. It was shown that RAPD-PCR-method can be successfully used in the analysis of interspecifi c diff erences of insects, along with other molecular-genetic methods. The performed studies allowed us to assess the eff ectiveness of the RAPD-primers identifi ed in the work for diff erentiating the species of lace bugs and to obtain information on the genetic relationship of the Tingidae family species. The primers identifi ed in the work are also eff ective for assessing DNA-polymorphism and genetic diversity of insects of the Tingidae family. This method of molecular-genetic diagnosis allows carrying out a more eff ective monitoring of pests of this insect family.

Entomopathogenic fungi have important roles in the natural regulation of many insect pests and pest populations. Several species of entomopathogenic fungi are being produced commercially and used as biological control agents against many insect pests in many parts of the world. They normally invade insects via the external cuticle and need not be ingested to initiate disease. This makes them prime candidates for use against plant and blood sucking insects. In Turkey, there are many insect pests in agricultural and forested area and, they cause great economic losses in these areas. Some studies showed that entomopathogenic fungi can be important biocontrol agents against many pest species in Turkey and, these pathogens have a potential to suppress population of some pest species in the field. In this review, we provide an overview of entomopathogenic fungi and the potential of entomopathogenic fungi for controlling some pest species

Aim. The aim of the work was to study the species diversity of pests of the suborder of shield bugs (Heteroptera) in agrocenoses of the Lazarevsky district of Sochi.This paper presents data on the distribution, abundance and density of Heptoptera pest populations in this location. Heteroptera were gathered twice a month during the growing season (April to October) and weekly in the autumn‐winter period (November to March). The choice of registration date during the growing season was determined by the appearance of the first phytophagous individuals after wintering. Identification of the identified phytophages was carried out in the laboratories of the station according to generally accepted methods.The paper presents data on the distribution, abundance and density of pest populations of the suborder of shield bugs (Heteroptera) in the Lazarevsky district of Sochi, Krasnodar Territory. As a result of this research, the species composition of the most common species of bedbugs in this area has been revealed. The most harmful species noted were: berry shield Dolycoris baccarum Linnaeus, 1758; ornate shield Eurydema ornata Linnaeus, 1758; Green shield Nezara viridula Linnaeus, 1758; ruled shield Graphosoma lineatum Linnaeus, 1758; brown‐marbled bug Halyomorpha halys Stål, 1855; oak lace‐maker Corythucha arcuata Say, 1832; sycamore lace‐maker Corythucha ciliata Say; pear lace‐maker Stephanitis pyri Fabricius and linden bug Oxycarenus lavaterae Fabricius, 1787.As a result of the research undertaken, an increase in the total number of bedbug populations, an expansion of trophic connections, an increase in aggressiveness and a change in the status of individual pest species were revealed.