Bionomics and host plants of the invasive Cydia interscindana (Möschler, 1866) (Lepidoptera, Tortricidae), an emerging pest in the Carpathian Lowlands

Cydia interscindana (Möschler, 1866) has spread through several European countries in the past few years, becoming an invasive pest of ornamental trees. It was collected in Hungary for the first time in a pheromone trap set for Cydia pomonella (Linnaeus, 1758) in 2014. Here we discuss its recent distribution in Hungary based on intensive sampling between 2018 and 2020, which showed the dispersal of the pest by humans. Two formerly unknown host plants are also recorded. The damage caused by the larvae, the external morphology of the adult male, larva, pupa (described for the first time) and pupal exuviae are presented. We also analyse DNA barcodes, identifying this pest for the first time via DNA sequencing of immature stages. Introduction Cydia interscindana is native in the Mediterranean region, where it was described by Möschler in 1866 from Andalusia. It is distributed in Mediterranean countries including Portugal (Corley 2004), Spain (Férriz et al. 2006), France (Lévêque et al. 2017) and Italy (Minelli 1995). Later the species was recorded in the British Isles (Knill-Jones 2020), Belgium (De Prins 2016), Switzerland (Swisslepteam 2010), Slovakia (Pastorális et al. 2018) and Russia (Caucasus; Schurov et al. 2017). In Hungary, Cydia interscindana adults were caught by a sticky delta pheromone trap (CSALOMON RAG type) for Cydia pomonella (Linnaeus 1758) in 2014 during a study on swarming dynamics of the latter pest in Budapest. This provided the first record of the species in the Carpathian basin (Szabóky 2014; Takács and Szabóky 2015). In the Mediterranean region larvae feed on Juniperus oxycedrus (L.) (Miller 1990). In Belgium the larva was recorded on Juniperus spp. (Meert et al. 2019). J. oxycedrus is not native in Hungary, but Cupressus × leylandii A.B. Jacks. & Dallim 1926, Platycladus orientalis (L.) Franco 1949 and Chamaecyparis lawsoniana (A. Murray bis) Parl. 1864 are popular evergreens used as ornamental trees both in parks and gardens. In Hungary several pests of these plants have been recorded, all probably introduced with imported plants; in the literature, 11 Lepidoptera, nine Coleoptera and six Hemiptera species have been mentioned already (Csóka and Kovács 1999; Maráczi 2013; Bozsik et al. 2016; Schurov et al. 2017). However, until the end of the 2000s, only Scolytidae (Coleoptera) species caused serious damage (Bozsik and Szőcs 2017). In 2012, an outbreak of the formerly detected (Muskovits 2001) Lamprodila festiva (Linnaeus 1767) (Buprestidae) took place in Budapest (Németh 2012) causing serious damage on Platycladus orientalis and several ornamental gymnosperm species. This outbreak was certainly caused by introduced specimens, that had arrived with trees from the Mediterranean region where this beetle is a well-known pest (Merkl 2016), whose abundance in Hungary increases due to climatic change (Csóka et al. 2018). Based on the available data, in Hungary this beetle pest has also been blamed for all the damage caused on Cupressus, Platycladus and Chamaecyparis trees and management has been carried out only against them. In 2018, a larva of L. festiva, an unidentified caterpillar and a freshly emerged specimen of Cydia interscindana were collected simultaneously from a Leyland cypress in Székesfehérvár (Central Hungary). In that year, similar Lepidoptera larvae were found in three neighbouring villages: Velence, Sukoró and Pákozd. To identify the sampled caterpillar, DNA analysis was undertaken. Additionally, in 2019–2020 a country-wide investigation was carried out to map the distribution and abundance of C. interscindana and gather data on bionomics of this pest in the Carpathian basin.

An Open-Source Low-Cost Imaging System Plug-In for Pheromone Traps Aiding Remote Insect Pest Population Monitoring in Fruit Crops

This note describes the development of a plug-in imaging system for pheromone delta traps used in pest population monitoring. The plug-in comprises an RGB imaging sensor integrated with a microcontroller unit and associated hardware for optimized power usage and data capture. The plug-in can be attached to the top of a modified delta trap to realize periodic image capture of the trap liner (17.8 cm × 17.8 cm). As configured, the captured images are stored on a microSD card with ~0.01 cm2 pixel−1 spatial resolution. The plug-in hardware is configured to conserve power, as it enters in sleep mode during idle operation. Twenty traps with plug-in units were constructed and evaluated in the 2020 field season for codling moth (Cydia pomonella) population monitoring in a research study. The units reliably captured images at daily interval over the course of two weeks with a 350 mAh DC power source. The captured images provided the temporal population dynamics of codling moths, which would otherwise be achieved through daily manual trap monitoring. The system’s build cost is about $33 per unit, and it has potential for scaling to commercial applications through Internet of Things-enabled technologies integration.

Genome-Wide Selective Signature Analysis Revealed Insecticide Resistance Mechanisms in Cydia pomonella

The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a serious invasive pest of pome fruits. Currently, C. pomonella management mainly relies on the application of insecticides, which have driven the development of resistance in the insect. Understanding the genetic mechanisms of insecticide resistance is of great significance for developing new pest resistance management techniques and formulating effective resistance management strategies. Using existing genome resequencing data, we performed selective sweep analysis by comparing two resistant strains and one susceptible strain of the insect pest and identified seven genes, among which, two (glycine receptor and glutamate receptor) were under strong insecticide selection, suggesting their functional importance in insecticide resistance. We also found that eight genes including CYP6B2, CYP307a1, 5-hydroxytryptamine receptor, cuticle protein, and acetylcholinesterase, are potentially involved in cross-resistance to azinphos-methyl and deltamethrin. Moreover, among several P450s identified as positively selected genes, CYP6B2, CYP4C1, and CYP4d2 showed the highest expression level in larva compared to other stages tested, and CYP6B2 also showed the highest expression level in midgut, supporting the roles they may play in insecticide metabolism. Our results provide several potential genes that can be studied further to advance understanding of complexity of insecticide resistance mechanisms in C. pomonella.

Nondestructive Detection of Codling Moth Infestation in Apples Using Pixel-Based NIR Hyperspectral Imaging with Machine Learning and Feature Selection

Codling moth (CM) (Cydia pomonella L.), a devastating pest, creates a serious issue for apple production and marketing in apple-producing countries. Therefore, effective nondestructive early detection of external and internal defects in CM-infested apples could remarkably prevent postharvest losses and improve the quality of the final product. In this study, near-infrared (NIR) hyperspectral reflectance imaging in the wavelength range of 900–1700 nm was applied to detect CM infestation at the pixel level for three organic apple cultivars, namely Gala, Fuji and Granny Smith. An effective region of interest (ROI) acquisition procedure along with different machine learning and data processing methods were used to build robust and high accuracy classification models. Optimal wavelength selection was implemented using sequential stepwise selection methods to build multispectral imaging models for fast and effective classification purposes. The results showed that the infested and healthy samples were classified at pixel level with up to 97.4% total accuracy for validation dataset using a gradient tree boosting (GTB) ensemble classifier, among others. The feature selection algorithm obtained a maximum accuracy of 91.6% with only 22 selected wavelengths. These findings indicate the high potential of NIR hyperspectral imaging (HSI) in detecting and classifying latent CM infestation in apples of different cultivars.

Green Chemistry Production of Codlemone, the Sex Pheromone of the Codling Moth (Cydia pomonella), by Metabolic Engineering of the Oilseed Crop Camelina (Camelina sativa)

Synthetic pheromones have been used for pest control over several decades. The conventional synthesis of di-unsaturated pheromone compounds is usually complex and costly. Camelina (Camelina sativa) has emerged as an ideal, non-food biotech oilseed platform for production of oils with modified fatty acid compositions. We used Camelina as a plant factory to produce mono- and di-unsaturated C12 chain length moth sex pheromone precursors, (E)-9-dodecenoic acid and (E,E)-8,10-dodecadienoic acid, by introducing a fatty acyl-ACP thioesterase FatB gene UcTE from California bay laurel (Umbellularia californica) and a bifunctional ∆9 desaturase gene Cpo_CPRQ from the codling moth, Cydia pomonella. Different transgene combinations were investigated for increasing pheromone precursor yield. The most productive Camelina line was engineered with a vector that contained one copy of UcTE and the viral suppressor protein encoding P19 transgenes and three copies of Cpo_CPRQ transgene. The T2 generation of this line produced 9.4% of (E)-9-dodecenoic acid and 5.5% of (E,E)-8,10-dodecadienoic acid of the total fatty acids, and seeds were selected to advance top-performing lines to homozygosity. In the T4 generation, production levels of (E)-9-dodecenoic acid and (E,E)-8,10-dodecadienoic acid remained stable. The diene acid together with other seed fatty acids were converted into corresponding alcohols, and the bioactivity of the plant-derived codlemone was confirmed by GC-EAD and a flight tunnel assay. Trapping in orchards and home gardens confirmed significant and specific attraction of C. pomonella males to the plant-derived codlemone.

An investigation into yeast-baculovirus synergism for the improved control of Thaumatotibia leucotreta, an economically important pest of citrus

A mutualistic association between Cydia pomonella and yeasts belonging to the genus Metschnikowia has previously been demonstrated. Larval feeding galleries inoculated with M. andauensis, reduced larval mortality and enhanced larval development. Additionally, adult C. pomonella female oviposition preference was also shown to be influenced by the volatiles produced by M. andauensis. This mutualistic relationship was manipulated for biological control purposes, by combining M. pulcherrima with the baculovirus Cydia pomonella granulovirus. The combination of M. pulcherrima with brown cane sugar and CpGV in laboratory assays and field trials resulted in a significant increase in larval mortality. A similar observation was made when M. pulcherrima was substituted for Saccharomyces cerevisiae. This indicates that yeasts harbour the potential for use in biological control, especially when combined with other well-established biocontrol methods. Thaumatotibia leucotreta is a phytophagous insect endemic to southern Africa. It is highly significant to the South African citrus industry due to its classification as a phytosanitary pest by most international markets. An integrated pest management programme has been implemented to control T. leucotreta. The baculovirus Cryptophlebia leucotreta granulovirus forms one component of this programme and is highly effective. In this study, we proposed to determine which yeast species occur naturally in the gut of T. leucotreta larvae and to examine whether any of the isolated yeast species, when combined with the CrleGV-SA, enhance its effectiveness. Firstly, Navel oranges infested with T. leucotreta larvae were collected from geographically distinct citrus-producing regions across South Africa. This led to the isolation and identification of six yeast species from the gut of T. leucotreta larvae via PCR amplification and sequencing of the internal transcribed spacer region and D1/D2 domain of the large subunit. Six yeast species were identified, viz. Meyerozyma guilliermondii, Hanseniaspora uvarum, Clavispora lusitaniae, Kluyveromyces marxianus, Pichia kudriavzevii and Pichia kluyveri. Additionally, Saccharomyces cerevisiae was included as a control in all trials due to its commercial availability and use in the artificial diet used to rear T. leucotreta. Secondly, larval development and attraction assays were conducted with the isolated yeast species. Thaumatotibia leucotreta larvae that fed on Navel oranges inoculated with M. guilliermondii, P. kluyveri, H. uvarum, and S. cerevisiae had accelerated developmental periods and reduced mortality rates. Additionally, it was demonstrated that T. leucotreta neonates were attracted to YPD broth cultures inoculated with P. kluyveri, H. uvarum, P. kudriavzevii and K. marxianus for feeding. Thirdly, oviposition preference assays were conducted with adult T. leucotreta females to determine whether the isolated yeast species influence their egg-laying in two-choice and multiple-choice tests. Navel oranges were inoculated with a specific yeast isolate, and mated adult females were left to oviposit. Meyerozyma guilliermondii, P. kudriavzevii and H. uvarum were shown to influence adult T. leucotreta female oviposition preference in two-choice tests. However, multiple-choice tests using the aforementioned yeast species did not mimic these results. Lastly, a series of detached fruit bioassays were performed to determine the optimal yeast:virus ratio, test all isolated yeast species in combination with CrleGV-SA and to further enhance yeast/virus formulation through the addition of an adjuvant and surfactant. CrleGV-SA was applied at a lethal concentration that would kill 50 % of T. leucotreta larvae. The optimal yeast concentration to use alongside CrleGV-SA was determined. Pichia kluyveri, P. kudriavzevii, K. marxianus and S. cerevisiae in combination with CrleGV-SA increased larval mortality compared to CrleGV-SA alone. The inclusion of molasses and BREAK-THRU® S 240 to P. kudriavzevii and S. cerevisiae plus CrleGV-SA formulations greatly enhanced their efficacy. Additionally, semi-field trials were initiated using P. kudriavzevii and S. cerevisiae, with promising preliminary results being obtained, although more replicates need to be performed. The experiments performed in this study provide a platform for further research into the application of a yeast/virus combination as a novel control and monitoring option for T. leucotreta in the field.

Studierea influenţei componenţilor minori asupra eficienţei feromonilor sexuali ai viermelui mărului

In this paper is reported the evaluation of biological efficacy of two minor components that was added to the basic sex pheromone component Cydia pomonella L., E8, E10-C12-OH. The use of minor component- C.M.-1 of increasing concentrations in binary mixture compositions with the basic sex phe-romone component of codling moth on pheromone-impregnated rubber septa in delta pheromone traps has shown an increased effectiveness by 56-62% in field trials on apple orchard. At the same time, the number of males caught in delta pheromone traps where were used minor component - C.M.-2 in binary mixture compositions increased by 29-35%. Auxiliary research is still needed.

Cross-Resistance of the Codling Moth against Different Isolates of Cydia pomonella Granulovirus Is Caused by Two Different but Genetically Linked Resistance Mechanisms

Cydia pomonella granulovirus (CpGV) is a widely used biological control agent of the codling moth. Recently, however, the codling moth has developed different types of field resistance against CpGV isolates. Whereas type I resistance is Z chromosomal inherited and targeted at the viral gene pe38 of isolate CpGV-M, type II resistance is autosomal inherited and targeted against isolates CpGV-M and CpGV-S. Here, we report that mixtures of CpGV-M and CpGV-S fail to break type II resistance and is expressed at all larval stages. Budded virus (BV) injection experiments circumventing initial midgut infection provided evidence that resistance against CpGV-S is midgut-related, though fluorescence dequenching assay using rhodamine-18 labeled occlusion derived viruses (ODV) could not fully elucidate whether the receptor binding or an intracellular midgut factor is involved. From our peroral and intra-hemocoel infection experiments, we conclude that two different (but genetically linked) resistance mechanisms are responsible for type II resistance in the codling moth: resistance against CpGV-M is systemic whereas a second and/or additional resistance mechanism against CpGV-S is located in the midgut of CpR5M larvae.