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.

Evaluation of Optimal Reference Genes for qRT-PCR Analysis in Hyphantria cunea (Drury)

The relative quantification of gene expression is mainly achieved through reverse transcription-quantitative PCR (qRT-PCR); however, its reliability and precision rely on proper data normalization using one or more optimal reference genes. Hyphantria cunea (Drury) has been an invasive pest of forest trees, ornamental plants, and fruit trees in China for many years. Currently, the molecular physiological role of reference genes in H. cunea is unclear, which hinders functional gene study. Therefore, eight common reference genes, RPS26, RPL13, UBI, AK, RPS15, EIF4A, β-actin, α-tub, were selected to evaluate levels of gene expression stability when subjected to varied experimental conditions, including developmental stage and gender, different tissues, larvae reared on different hosts and different larval density. The geNorm, BestKeeper, ΔCt method, and NormFinder statistical algorithms were used to normalize gene transcription data. Furthermore, the stability/suitability of these candidates was ranked overall by RefFinder. This study provides a comprehensive evaluation of reference genes in H. cunea and could help select reference genes for other Lepidoptera species.

Early Starvation Contributes to the Adaptive Capacity of Corythucha marmorata (Uhler), an Emerging Pest in China

Food shortages severely reduce the prospects of insect survival in natural settings, including in the case of herbivorous insects. However, the early starvation experience of some insects has positive effects throughout their entire lifespan. It is important to discuss the effects of refeeding and host plants on the capacity of herbivorous insects to adapt to starvation and low temperatures, considering that starvation resistance is expected to show some degree of adaptive phenotypic plasticity. We tested the relationship between host plant, starvation, and the supercooling capacity of the invasive pest Corythucha marmorata. In particular, we highlighted how early starvation affects the refeeding and recovery phases. Among the various range of hosts, the chrysanthemum lace bug has the fastest growth rate on Helianthus annuus, and the strongest supercooling capacity on Symphyotrichum novi-belgii. Especially, starvation for 2 days increases the rates of survival, development, and number of eggs upon refeeding, in comparison to no starvation. A 3-day starvation period in the nymphal stage significantly increased the supercooling capacity of 5th instar nymphs and adults, as observed in our study.

Monitoring of damage and distribution of invasive fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) on maize crop in Karo, North Sumatera, Indonesia

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is an invasive pest from America and has recently become an important pest in Indonesia. In their new environment, these pests have very high migratory and adaptive skills, as well as aggressive feeding habits. The aim of this research was to monitor the distribution, percentage of attacks, and damage caused by S. frugiperda on maize fields in the Karo District of North Sumatra Province. The study was conducted using a survey method at various altitudes and the sample unit was determined using the diagonal method. Each sample unit has a size of 2 × 2 m2. The age of maize crop used as the sample is 2-4; 5-6; 7-8; 9-10; and 11 weeks after planting (wap). Symptoms of attack, number of larvae population, and percentage of FAW attack were observed directly on plants. The results showed that FAW spread evenly at various altitudes, with the highest population at an altitude of 500-1,000 m.a.s.l at the age of 2-4 wap with a larval population density of 14.20 individual/unit sample. The highest percentage of attack was found at an altitude of 500-1,000 m.a.s.l, namely 82% at 2-4 wap. The highest attack on leaves occurred at an altitude of 500-1,000 m.a.s.l (70.6%) at the age of 2-4 wap.

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.

Biorational management of maize fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) using Bacillus thuringiensis (Berliner) enriched with chemical additives

An invasive pest, fall armyworm, Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae) attacks maize at every stage of development, from seedling emergence up to cob formation. Early instar larvae were seen mostly on leaves of maize with characteristics pin or shot hole symptoms. Later instar larvae were confined to deep whorls, leaving typically ragged like appearance and fed on the reproductive stage of the crop especially tassels and developing cobs resulting in quality and quantity loss of maize produce. The effect of commercially available Bacillus thuringiensis subsp. kurstaki product, Dipel® against the second instar larvae of Fall Armyworm (FAW )was not promising under laboratory conditions. Hence, an effort was made to add an adjuvant along with B. thuringiensis to increase the virulence of commercially available B. thuringiensis.The Laboratory bioassays with B. thuringiensis and seven chemical additives ( T1- Bt + Boric acid, T2- Bt + Zinc oxide, T3- Bt + Sodium nitrate, T4- Bt + Peptone, T5- Bt + Urea, T6- Bt + EDTA, T7- Bt + Citric acid & T8- Bt alone T9- Control) were tested against second instar larvae of Spodoptera frugiperda larvae. The results showed that B. thuringiensis plus sodium nitrate (T3) promoted maximum mortality 82.2 per cent with a minimum LC50 value of 54.620 mg/l. Sodium nitrate boosted B. thuringiensis activity at a concentration of 0.05 per cent by 2.128-fold than B. thuringiensis alone. Overall, sodium nitrate improved the efficacy of B. thuringiensis spray at the maximum level followed by boric acid, urea, EDTA and peptone.