Invasive Pest Research Articles

First Report of <i>Tetrastichus howardi</i> (Olliff) and <i>Chelonus formosanus</i> Sonan as parasitoids of fall armyworm, <i>Spodoptera frugiperda</i> (J.E. Smith), in Pakistan

Fall armyworm, Spodoptera frugiperda (J.E. Smith), an invasive agricultural pest, causes substantial economic losses in Pakistan. This study reports the first record of Tetrastichus howardi (Olliff) and Chelonus formosanus Sonan as natural enemies parasitising S. frugiperda within the country. Parasitoids were collected from infested maize fields and identified through morphological analysis. This discovery enhances our understanding of the natural enemy complex associated with S. frugiperda in Pakistan and provides a foundation for investigating their potential as biological control agents. These findings underscore the potential of these parasitoids as components of integrated pest management systems to diminish reliance on chemical insecticides and foster sustainable agricultural practices.

New host plant records of rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hymenoptera: Sternorrhyncha: Aleyrodidae) in diverse habitats

The current study focused on assessing the prevalence of invasive whitefly infestation in diverse habitats in the Saurashtra region of Gujarat. The study revealed the presence of Aleurodicus rugioperculatus Martin, specifically in Punica granatum, Ficus religiosa, Ficus benghalensis, Borassus flabellifer, Cordia myxa, Pennisetum purpureum, Azadirachta indica and Citrus limon during the survey conducted in 2023–24. This infestation of Aleurodicus rugioperculatus Martin with different host plants marks the first documented occurrence of this novel invasive whitefly species affecting India. These findings highlight the need for further research and management strategies to address the threats posed by this invasive pest.

Factors influencing adoption of agro-ecological pest management options for mango fruit fly under information constraints: a two-part fractional regression approach

The catalytic effect of climate change on the emergence and prevalence of invasive alien pests along with weak pesticide regulatory frameworks in developing countries calls for a transition towards sustainable pest management. Agro-ecological pest management (APM) offers a nature-based, cost-effective alternative for addressing systemic pest challenges, such as mango fruit fly invasion. We applied a two-part fractional regression to sequentially model APM adoption and intensity decisions among 423 smallholder mango orchard managers from Makueni County, Kenya. Despite APM’s potential, we observed moderate adoption rates (56.7%), with the average adopter implementing only 25% of the APM practices concurrently. Farmers’ socio-psychological attributes significantly influenced both adoption and intensity decisions. While perceptions of technology attributes and institutional and social factors primarily influenced both the adoption and intensity decisions, information constraints, resource endowment, gender and inter-generational factors significantly influenced only the intensity decision. To support the transition from synthetic insecticides to APM measures, policymakers should create more opportunities for awareness creation, training and knowledge co-creation and co-production, particularly through social networks and gender-disaggregated participatory group approaches.

A biosecurity perspective on urban trees in public and private spaces and trees available from nurseries

Urban trees are of high importance for healthy urban ecosystems. However, some trees are invasive plants that may ‘escape’ from urban areas into natural environments. Furthermore, invasive forest pests often arrive and establish in urban environments before they spread to forest ecosystems. Therefore, knowledge of tree species composition in urban areas is important for the biosecurity of cities and surrounding forests. Despite this, urban tree inventories often lack information on trees on private properties. To assess the potential role of urban areas as a source of invasive trees as well as invasive pests of trees, we compared the species composition of urban trees in public and private spaces in several Swiss cities and in tree nurseries (henceforth: ‘nurseries’) in Switzerland. We analysed the various data sets we compiled regarding invasive tree species, and examined how many trees are potential hosts for invasive quarantine pests of trees. We found no statistically significant difference in tree species composition in public and private urban areas, but the proportion of non-native trees was higher in private than in public spaces. Tree species available in nurseries and those present in cities were not significantly different, with larger urban tree inventories having a greater overlap with the species available in nurseries. Five of eight tree species considered invasive whose sale was banned since September 2024 were still on sale ten months before the ban came into force. All eight tree species were present in urban tree inventories. Importantly, between 91 % and 97 % of all urban trees in public and private spaces were suitable hosts for at least one quarantine forest pest. Given the pivotal role that urban trees play for the health of urban and peri-urban ecosystems, knowledge of tree species composition is essential from a biosecurity perspective. Our findings suggest that the combination of public urban tree inventories and trees available from nurseries can provide an estimate of the composition of private urban trees and can be useful for invasive species monitoring.

Loss-of-function in testis-specific serine/threonine protein kinase triggers male infertility in an invasive moth

Genetic biocontrol technologies present promising and eco-friendly strategies for the management of pest and insect-transmitted diseases. Although considerable advancements achieve in gene drive applications targeting mosquitoes, endeavors to combat agricultural pests have been somewhat restricted. Here, we identify that the testis-specific serine/threonine kinases (TSSKs) family is uniquely expressed in the testes of Cydia pomonella, a prominent global invasive species. We further generated male moths with disrupted the expression of TSSKs and those with TSSKs disrupted using RNA interference and CRISPR/Cas9 genetic editing techniques, resulting in significant disruptions in spermiogenesis, decreased sperm motility, and hindered development of eggs. Further explorations into the underlying post-transcriptional regulatory mechanisms reveales the involvement of lnc117962 as a competing endogenous RNA (ceRNA) for miR-3960, thereby regulating TSSKs. Notably, orchard trials demonstrates that the release of male strains can effectively suppress population growth. Our findings indicate that targeting TSSKs could serve as a feasible avenue for managing C. pomonella populations, offering significant insights and potential strategies for controlling invasive pests through genetic sterile insect technique (gSIT) technology.

Pre-emptive augmentative biological control of Spodoptera frugiperda in Europe using Trichogramma spp.

BackgroundFall armyworm, Spodoptera frugiperda, is a highly invasive pest of maize and other crops worldwide. It has recently been detected in Europe, and it is urgent to test and develop new sustainable control methods adapted to the European context and market. Trichogramma spp. are egg parasitoids that are sometimes used as biological control agent against S. frugiperda in other continents. However, a major issue using Trichogramma spp. against this pest is that females cannot reach all eggs in an egg mass, which is usually composed of one to three layers of eggs, often covered with scales and hair. Three European Trichogramma species were tested for their ability to parasitize egg masses with one to three layers and with or without hair and scale cover.MethodsTrichogramma brassicae, T. dendrolimi and T. cacoeciae were offered five types of S. frugiperda egg masses: one-layer without hair; one-layer with hair; two-layers without hair; two-layers with hair; three-layers with hair. For each treatment, an egg mass laid on paper was placed in a small vial saturated with females, to be sure that all reachable eggs would be parasitized. For each egg mass, the number of eggs in each layer was counted. Fifteen replicates were made per treatment, as well as 10 control vials without Trichogramma sp. Parasitism rates were calculated for each egg mass.ResultsThere were significant differences in the ability of parasitoid species to oviposit through hair and scales and to reach the lower egg layers. Trichogramma dendrolimi was the most efficient species and T. cacoeciae the least. Depending on the number of egg layers and hair and scales, parasitism rates by T. brassicae, T. dendrolimi and T. cacoeciae varied between 99 and 41%, 100 and 43% and 100 and 28%, respectively.ConclusionsThe assays confirmed that Trichogramma females cannot easily oviposit through thick layers of hair and scales but overall parasitism rates were higher than found previously. Important variations between species were found, and more Trichogramma sp. and other local natural enemies should be tested pre-emptively before S. frugiperda has invaded Europe.

Assessing the feasibility of pre-emptive biological control against the emerald ash borer, Agrilus planipennis, an imminent biosecurity threat to Europe

As the globalisation of trade increases, so does the spread of arthropod pests, leading to a growing focus on biosecurity preparedness. One approach to this is pre-emptive biological control, involving the importation of classical biological control (CBC) agents for risk assessments and acquiring approval for their release prior to the expected arrival of their target pests. This aims to mitigate the economic and/or environmental consequences of a delayed biological control response to pest invasions. Guidelines to assess the feasibility of pre-emptive biological control for high priority pests were recently developed. Emerald ash borer (EAB), Agrilus planipennis, is an invasive woodboring pest of ash (Fraxinus spp.) in North America, European Russia and Ukraine, and is spreading westward into Europe, threatening the future of European ash (Fraxinus excelsior). We applied the aforementioned guidelines to assess the feasibility of pre-emptive biological control in Europe using four EAB parasitoids, already released in North America for CBC. Three of the parasitoids; Oobius agrili, Spathius galinae, and Tetrastichus planipennisi, were found suitable for pre-emptive biological control. The fourth parasitoid, Spathius agrili, was found to have limited establishment in new environmental conditions, and was therefore deemed less suitable for pre-emptive biological control of EAB in Europe. This assessment can inform scientists and regulators in Europe on the most promising EAB parasitoids that should be considered for pre-emptive applications for importation and risk assessment to acquire pre-approval for immediate release should the target pest subsequently be discovered. In turn, this study contributes to the development of biosecurity preparedness against EAB’s imminent spread throughout Europe.

Carvacrol acts on the larval midgut of Spodoptera frugiperda by destroying the tissue structure and altering the bacterial community

The fall armyworm, Spodoptera frugiperda, has become a global invasive pest in recent years, threatening agricultural production. Carvacrol (CAR) is a multifunctional plant-derived compound and exhibited significant bioactivities against many pests. Our previous study found that CAR inhibited growth and development in S. frugiperda. However, the effects of CAR on the midgut of this pest remain unknown. In this study, the actions of CAR on the larval midgut of S. frugiperda were investigated. The results found that 1.0 and 2.0 g/kg CAR treatments destroyed the structure of the larval midgut based on hematoxylin-eosin staining and transmission electron microscope observation. In addition, 2.0 g/kg CAR exposure significantly altered the larval midgut bacterial community composition and structure. The results of the linear discriminant analysis effect size (LEfSe) analysis suggest that six bacterial genera contributed to the different structures of the larval bacterial community. Furthermore, PICRUSt2 analysis found that 16 bacterial function categories were altered by CAR treatment, of which 8 were significantly increased. Our results provided new insight into the toxicological mechanisms of CAR against S. frugiperda larvae and laid the foundation for the field application of S. frugiperda control.

Potential distribution of Acerophagus papayae, a parasitoid of the papaya mealybug (Paracoccus marginatus), across Africa

The papaya mealybug, Paracoccus marginatus, is a highly polyphagous invasive pest that affects at least 133 economically important crops, and causes economic losses worldwide. Acerophagus papayae (Noyes and Schauff), a parasitic wasp, has proven to be a successful biocontrol agent, but its use in Africa is limited. Here, we use a predictive correlative model to explore the potential distribution of A. papayae and relate it to data showing the potential distribution of P. marginatus, to highlight potentially suitable areas for biological control of P. marginatus, for its current distribution, as well as its potential future distribution.The resulting model performed well with a test AUC of 0.89. Areas that were highly suitable for P. marginatus and were also suitable for A. papayae were highest across West Africa. Whilst there were areas which were suitable for both species in both East Africa and Central Africa, there were large areas of cropping land which were highly suitable for P. marginatus although not suitable for A. papayae. Across Northern and Southern Africa, there were limited cropping areas which were suitable for P. marginatus and where there was suitability, it was only moderate. Across these areas, there was limited suitability for A. papayae.Our results offer refined information on the potential suitability for A. papayae across Africa with the aim to help guide decisions on the areas where use of A. papayae could be used effectively as a part of an integrated pest management programme against P. marginatus.

A potential trade-off between reproduction and enhancement of thermotolerance in Liriomyza trifolii populations driven by thermal acclimation

The invasive pest, Liriomyza trifolii, poses a significant threat to ornamental and vegetable plants. It spreads rapidly and causes large-scale outbreaks with pronounced thermotolerance. In this study, we developed L. trifolii strains adapted to high temperatures (strains designated 35 and 40); these were generated from a susceptible strain (designated S) by long-term thermal acclimation to 35 °C and 40 °C, respectively. Age-stage, two-sex life tables, thermal preferences, critical thermal limits, knockdown behaviors, eclosion and survival rates as well as expression of genes encoding heat shock proteins (Hsps) were compared for the three strains. Our findings indicated that the thermotolerance of L. trifolii was enhanced after long-term thermal acclimation, which suggested an adaptive plastic response to thermal stress. A trade-off between reproduction and thermotolerance was observed under thermal stress, potentially improving survival of the population and fostering adaptionary changes. Acclimation at 35 °C improved reproductive performance and population density of L. trifolii, particularly by enhancing the fecundity of female adults and accelerating the speed of development. Although the 40 strain exhibited the highest developmental speed and greater thermotolerance, it incurred a larger reproductive cost. This study provides a theoretical framework for monitoring and controlling leafminers and understanding their evolutionary adaptation to environmental changes.

Symbiont community assembly shaped by insecticide exposure and feedback on insecticide resistance of Spodoptera frugiperda

Exploring the mechanism of microbiota assembly and its ecological consequences is crucial for connecting microbiome variation to ecosystem function. However, the influencing factors underlying microbiota assembly in the host-microbe system and their impact on the host phenotype remain unclear. Through investigating the prevalent and worsening ecological phenomenon of insecticide resistance in global agriculture, we found that insecticide exposure significantly changed the gut microbiota assembly patterns of a major agricultural invasive insect pest, Spodoptera frugiperda. The relative importance of various microbiota assembly processes significantly varied with habitat heterogeneity and heterogeneous selection serving as a potential predictor of the host’s insecticide resistance in field populations. Moreover, disturbance of the gut microbiota assembly through antibiotics was revealed to significantly affect the rate and heritability of insecticide resistance evolution, leading to a delay in insecticide resistance evolution in this insect pest. These findings indicate that the gut microbiota assembly process of the insect host is influenced by persistent exposure to habitat conditions, particularly insecticides. This variation in insecticide exposure-related community assembly process subsequently influences the insect host’s insecticide resistance phenotype. This study provides insights into gut microbiota assembly processes from a symbiotic perspective and underscores the significant impact of symbiotic community changes on host phenotypic variation.

Strengthening plant health systems in South Sudan: addressing challenges and enhancing system efficiency and sustainability

Climate change-induced invasive pests remain a major bottleneck to agricultural productivity and food security in South Sudan. Strengthening the plant health system has the potential to contribute to reducing crop losses caused by pests. A situational analysis was conducted to assess the current state and effectiveness of plant health functions in three counties in South Sudan. Descriptive findings of data collected from 960 farmers in Juba, Yambio, and Yei indicated low access to plant health services, including advisory and extension, training, and information. There was a high dependence on NGOs and UN agencies to provide plant health services, indicating a gap in government-led initiatives. The findings demonstrate a complex relationship between plant health services and on-farm practices and regional variations in access to plant health services and resources. The findings have crucial implications for the plant health system in South Sudan, requiring the need for service accessibility, government involvement in plant health systems, strengthening of the policy and regulatory frameworks, and inclusivity in service provision.

Analysis of the immune transcriptome of the invasive pest spotted wing drosophila infected by Steinernema carpocapsae.

Drosophila suzukii is a pest of global concern due to its great impact on several crops. The entomopathogenic nematode Steinernema carpocapsae was highly virulent to the larvae of the fly although some immune mechanisms were triggered along the infection course. Thus, to understand the gene activation profile we performed a comparative transcriptome of D. suzukii larvae infected with S. carpocapsae and Xenorhabdus nematophila to map the differentially expressed genes involved in the defence response. The analysis exposed the induction of genes involved in the humoral response such as the antimicrobial peptides and pattern-recognition receptors while there was a suppression of the cellular defence. Besides, genes involved in melanisation, and clot formation were downregulated hindering the encapsulation response and wound healing. After the infection, larvae were in a stress condition with an enrichment of metabolic and transport functionalities. Concerning the stress response, we observed variations of the heat-shock proteins, detoxification, and peroxidase enzymes. These findings set a genetical comprehensive knowledge of the host-pathogen relation of D. suzukii challenged with S. carpocapsae which could support further comparative studies with entomopathogenic nematodes.

Better preparedness for invasive crop pests in changing climate: Assessing the risk of western corn rootworm (Coleoptera: Chrysomelidae) colonization in global maize growing regions and future spread dynamics

AbstractThe establishment and spread of alien species in new areas pose a potential threat to global food security. Diabrotica virgifera virgifera LeConte is an invasive maize pest originally from Mexico, causing substantial economic damage to maize production across extensive areas of the United States and Europe. However, it has not yet invaded Asia or other regions. We used the Ensemble Model and Cellular Automaton to analyze the establishment and spread risk of this pest. The pest has not explored novel climates during past invasions, and the climatic ecological niche it occupied in Europe constitutes only a fraction of that in North America, indicating that the species still possesses the potential to spread further in Europe in the future. Currently, approximately 34% of global maize‐growing areas are at risk, with 25.5% facing a high establishment risk. By 2060, a significant northward spread is projected to occur in North America and Europe, while only a sporadic spread is expected in South America, Asia, Africa, or Oceania. Therefore, the adaptation of transnational management strategies may be necessary to prevent and control the risk of introduction and spread of this important maize pest into new areas of global maize production.

Investigating the impact of cross-shelf transport and local retention in the Black Sea Rim Current system on small pelagic fishes

Advection of pelagic fish larvae through ocean currents is a source of dispersal that is known to structure marine populations by directly impacting population success and persistence. To be able to understand fish population dynamics and manage existing fisheries it is therefore of importance to assess the extent of exchange between populations and determine the factors that drive it, which is still a challenge in fisheries research today. In this study, the output of a high-resolution basin-scale circulation model is used to calculate the dispersal probability from spawning areas and the remaining Black Sea for a range of commercially important fish such as anchovy, sprat, turbot, red mullet, and bluefish under different environmental conditions. The common trait of many commercially important species in the Black Sea is that they have pelagic larval stages of different time scales which are simulated by tracking virtual drifters in the simulated surface circulation of the Black Sea. Simulation results show that the dynamic current structure of the Black Sea causes low local retention of larvae. During spring and summer lower offshore transport and higher local retention is observed than in fall and winter, which is directly related to the Rim Current strength. The lowest offshore transport is observed on the northern northwestern shelf, the main spawning area for pelagic fish with still 24-32% of larvae transported offshore. Simulations show that pelagic fish species such as anchovy and sprat adopted different reproductive strategies through their species-specific traits. For the summer spawning species anchovy, timing, and location of spawning together with its short pelagic larval stage is shown to enhance retention on the northwestern shelf. Sprat with its long pelagic larval stage and winter spawning is more adapted to high offshore transport, making it unlikely that sprat is recruited to the same area as where it is spawned. This modeling framework provides a basis for investigating recruitment variability of pelagic fish species in the Black Sea specifically considering the impact of climate variability and provides a useful guide to the potential connectivity of marine populations or the spread of invasive pests in the Black Sea.

Fall Armyworm Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) in East Nusa Tenggara Province of Indonesia: Genetic Characterization and Strain Detection

<em>Spodoptera frugiperda</em> J.E. Smith (Lepidoptera: Noctuidae) is an invasive pest of corn plants spreading throughout the world, including East Nusa Tenggara (NTT), Indonesia. Despite the wide distribution, there is a lack of information on the strain or genetic diversity of the pest in NTT. Therefore, this study aimed to determine the strain of <em>S. frugiperda</em> from several areas in NTT with a molecular method using <em>cytochrome oxidase subunit 1</em> (<em>COI</em>)<em> </em>and <em>triose phosphate isomerase</em> (<em>Tpi</em>)<em> </em>gene markers. The<em> </em>samples were collected from 3 islands: Timor, Flores, and Sumba. Amplification of the marker genes was carried out using 3 specific primers to identify the strain obtained from samples. Subsequently, polymerase chain reaction (PCR) products were sequenced and the DNA sequences were analyzed using the BioEdit and BLAST programs. Phylogeny analyses were carried out using the MEGA 11 program to verify the strain group of samples with reference isolates from other countries found in GenBank. The PCR results showed product amplicon size 811 bp for the <em>CO1A</em> marker. Based on phylogeny tree analysis using <em>COI </em>marker, <em>S. frugiperda </em>from NTT showed 2 clades, namely corn and rice strains. The characterization results showed that <em>S. frugiperda</em> in NTT comprised 63.6% corn and 36.4% rice strains. <em>COIB </em>classified <em>S. frugiperda</em> from NTT into the h4 haplotype subgroup, while <em>Tpi </em>gene marker was in the corn strain. This study provided valuable information regarding the strain of <em>S. frugiperda</em> in Indonesia to determine the appropriate control strategy.

Distribution of Robinia pseudoacacia pests in the south of the Russian Far East

In recent years, one of the problems associated with introduced woody plant species has been the invasion of pests and diseases into their secondary habitats. Such an invader in Russia, including the Far East, is Robinia pseudoacacia L. In order to assess the distribution of pests of this species in the south of the Far East and to evaluate the damage caused by them, monitoring of plantations in populated areas of the region is necessary. The article provides data on the distribution of pests R. pseudoacacia – Euura tibialis (Newmann, 1837) (Hymenoptera: Tenthredinidae), Obolodiplosis robiniae (Hald.,1847) (Diptera: Cecidomyiidae) in the Primorsky Territory. Studies of the R. pseudoacacia plantings show that E. tibialis occurs in 9 of 24 localities. On each plant specimen, approximately 2–3%, in some cases up to 4%, of the leaf plates were damaged to a greater or lesser extent. The northernmost point of the pest distribution is the town of Luchegorsk, the southern point is the Slavyanka settlement. The most affected are the city of Ussuriysk and the village Sinij Gay. A pest such as O. robiniae is found in all the 24 surveyed settlements. The northernmost point of its distribution is the city of Luchegorsk, the southernmost point is the Hassan settlement. The most affected by this pest is the town of Artem, the town of Bolshoi Kamen, Khorol settlement, Tavrichanka village. Further monitoring of R. pseudoacacia plantations in the Primorsky Territory is necessary in order to determine the distribution of its pests and assess the damage they cause.

Absolute Configuration of the Invasive Mealybug Delottococcus aberiae (De Lotto) Sex Pheromone: Synthesis and Bioassay of Both Enantiomers.

The mealybug Delottococcus aberiae (De Lotto) (Hemiptera: Pseudococcidae) is an invasive pest reported in Europe at the end of the first decade of the 2000s, causing severe damage to citrus production in eastern Spain. In a previous work, (4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate was identified as the sex pheromone emitted by females, a new compound with an unusual β-necrodol skeleton possessing one stereocenter. This compound was assigned to the (-)-enantiomer but the absolute configuration was then not reported. In the present study, enantiomeric pure samples of both enantiomers were synthesized. X-ray diffraction analysis allowed the (-)-enantiomer, identical to the one emitted by virgin D. aberiae females, to be unequivocally identified as (-)-(R)-(4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate. Bioassays carried out to test the activity of both enantiomers under field conditions suggest that the presence of the (+)-(S)-enantiomer has detrimental effects on the activity of the racemates.

Interactions between invasive pests and pathogens in a native chestnut forest

The introduction in the same area of different invasive species can result in novel interactions, with unpredictable consequences. We carried out a study in Galicia (northwestern Iberian Peninsula) with the aim of clarifying the interactions between two invasive species Cryphonectria parasitica and Dryocosmus kuriphilus. In 2018, we selected five chestnut plots affected by both species. We compared trees affected only by the insect and trees affected by both the insect and the fungus with respect to attack level, gall characteristics, female size and fecundity, and concentrations of nitrogen, water and secondary metabolites. We also evaluated female preferences in a greenhouse assay. There were higher levels of attack in trees affected by both invaders. However, the greenhouse assay showed that ovipositing females do not preferentially choose trees attacked by the fungus. The presence of the fungus had no effect on the size, wall thickness, or hardness of D. kuriphilus galls, but larvae were smaller in trees also affected by the fungus. The fecundity of females was strongly related to the presence of chestnut blight; the number of eggs per female was almost double in trees affected by the fungus. There were no relations between blight and the nitrogen or water content in the galls, where the insects feed. There were also no effects of chestnut blight on the concentration of terpenes or phenols, but condensed tannins were higher in trees with chestnut blight. The higher tannins induced by chestnut blight may directly or indirectly benefit gall wasps. Positive relationships between condensed tannin concentration and reproductive performance of other gall makers were previously reported. Tannins can also improve the negative effects of environmental conditions inside the gall. Our results indicate that the presence of chestnut blight can increase the suitability of chestnut trees for the invasive insect, D. kuriphilus, through the increase in tannins due to the presence of the fungus.

Resistance monitoring of diamide insecticides and characterization of field-evolved chlorantraniliprole resistance among Chinese populations of the tomato pinworm Phthorimaea (=Tuta) absoluta (Lepidoptera: Gelechiidae)

The tomato pinworm, Phthorimaea (=Tuta) absoluta, is considered one of the most destructive and invasive insect pests worldwide, having developed significant resistance to many popular insecticides. In this study, we monitored the field resistance of P. absoluta populations from China to three diamide insecticides: flubendiamide, chlorantraniliprole, and cyantraniliprole. We found that one field population from Wuzhong City (WZ) exhibited high level of resistance to chlorantraniliprole. Using the WZ population and a susceptible reference strain (YN-S), we established a near-isogenic line (WZ-NIL) of P. absoluta with resistance to chlorantraniliprole. This strain also showed substantial cross-resistance to flubendiamide, and cyantraniliprole. Genetic analysis revealed that the inheritance of resistance to chlorantraniliprole in the WZ-NIL strain was autosomal and incompletely dominant. Additionally, the pesticide synergist piperonyl butoxide significantly inhibited chlorantraniliprole resistance by compromising P450 monooxygenase activity, which was significantly higher in the resistant strain. Furthermore, WZ-NIL had significantly prolonged developmental stages, lower pupation rates, reduced female fecundity, and lower egg hatchability than YN-S individuals. The fitness of WZ-NIL relative to YN-S was estimated to be 0.73, indicating significant fitness cost associated with chlorantraniliprole resistance. Rotating chlorantraniliprole with other insecticides that have different modes of action and degradation may be particularly useful for managing chlorantraniliprole resistance in P. absoluta.