Biological control of the invasive Thrips parvispinus (Karny) (Thysanoptera: Thripidae) using entomopathogenic nematodes

Thrips parvispinus (Karny) (Thysanoptera: Thripidae) is an invasive pest increasingly affecting ornamental production in Florida, with a rapid expansion in North America, Europe, and Africa. Current management relies heavily on chemical control, highlighting the need for more sustainable alternatives, such as entomopathogenic nematodes (EPNs). We evaluated six EPN species (Heterorhabditis bacteriophora, Heterorhabditis indica, Steinernema carpocapsae, Steinernema riobrave, Steinernema feltiae, and Steinernema kraussei) under laboratory conditions, using a rate of 200 IJ/cm². Subsequently, the four best-performing species (H. bacteriophora, H. indica, S. carpocapsae, and S. riobrave) were further tested under greenhouse conditions using mandevilla plants and soil applications at a rate of 100 IJ/cm². Trials were conducted at 27 °C, reflecting the average temperatures of the ornamental growing and shipping seasons in southern Florida, while applications targeted the prepupal and pupal soil-dwelling stages of the pest. Observations of the surviving adults were recorded. In laboratory trials, the application of H. bacteriophora, S. riobrave, H. indica, and S. carpocapsae reduced the recovery adult thrips by 20 - 36% compared to controls. Greenhouse trials demonstrated reductions in all treatments where EPNs were applied, with reductions of up to 60% in adult recovery in S. riobrave and S. carpocapsae. Environmental factors, including warm temperatures and low substrate moisture, helped explain the EPN performance, favoring warm-adapted and desiccation-tolerant species. This is the first report demonstrating EPN efficacy against T. parvispinus, suggesting its potential for integration as an alternative tool within IPM programs.

1 Introduction

Thrips parvispinus (Karny) (Thysanoptera: Thripidae) is an emerging pest of significant concern in tropical and subtropical regions, with a rapidly expanding host range and geographic distribution (Ahmed et al., 2023). Native to Southeast Asia, T. parvispinus has become invasive in various parts of the world, including Europe, the Caribbean, and, more recently, the United States, where it was first reported in Florida in the early 2020s (Soto-Adames, 2020). Since then, the pest has rapidly spread to additional states, including Georgia, North Carolina, South Carolina, Colorado (Ahmed et al., 2023), and California (Middleton, 2025), with interceptions in Ohio and Pennsylvania (Ahmed et al., 2023). The establishment of T. parvispinus in ornamental and vegetable production systems has posed serious challenges for integrated pest management (IPM), primarily due to its polyphagous behavior, which facilitates infestation across a wide range of tropical ornamental and vegetable crops (Ahmed et al., 2023; Srinivasnaik et al., 2025).

Thrips parvispinus has been reported to infest at least 43 plant species from 19 families and different crop types (Ahmed et al., 2023; Ahmed et al., 2024). Although studies on T. parvispinus biology are still in progress, it is generally accepted that its life cycle lasts around 13–14 days when feeding on peppers (Hutasoit et al., 2017). Females insert their eggs into the leaf tissue, and larvae pass through two instars, completing development within four to five days before pupating in the soil (Revynthi et al., 2024). This species is comparable to other destructive thrips, such as the western flower thrips (WFT) Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) and the melon thrips Thrips palmi Karny (Thysanoptera: Thripidae) (Mound and Collins, 2000). Injury by T. parvispinus is associated with the deformation of young leaves, affecting photosynthesis and disrupting normal growth (Lim, 1989). In vegetables, the impact on chili peppers is up to 23% in yield (Sastrosiswojo, 1991), in papaya its association with a saprophytic fungus, Cladosporium oxysporum, causes malformation of younger tissues affecting the top of the trees (Lim, 1989), while in ornamentals of the genera Dahlia, Chrysanthemum, Gardenia, Mandevilla, Anthurium and Ficus significant damage such as leaf scarring, distortion of new growth, and flower blemish can be inflicted diminishing their commercial value (Middleton, 2025). To date, T. parvispinus has not been associated with the transmission of any plant pathogen.

Management of T. parvispinus is particularly challenging in ornamental crops, where its feeding activity reduces crop marketability. The small size of this species, relative to other common thrips (Ahmed et al., 2023), and similar cryptic behavior allow it to go unnoticed until substantial damage has occurred. To address the high initial populations and the regulatory constraints experienced by nursery growers in southern and central Florida, research was conducted to provide a list of insecticides to be used in rotational programs (Ataide et al., 2024), in combination with studies aiming at the prevention of infestation and limiting the spread through disinfesting plant cuttings in commercial nurseries (Ataide et al., 2025a). However, as expected, chemical insecticides might offer incomplete and short-term suppression as part of an early incursion strategy (Ataide et al., 2025b). If not integrated with more sustainable alternatives, their continued use may lead to long-term problems, including insecticide resistance, negative environmental impacts, and adverse health effects on field workers and consumers.

Based on previous studies with closely related pests such as the WFT and the onion thrips Thrips tabaci Lindeman (Thysanoptera: Thripidae) (Summerfield et al., 2024), the biological control of T. parvispinus is a promising approach involving predatory insects, predatory mites, entomopathogenic fungi, and entomopathogenic nematodes (EPNs). However, much of this work remains in the early stages and requires further research and development to optimize its effectiveness and integration into pest management programs. In this regard, the work done by Summerfield et al. (2024) can be a model for exploring biological control strategies. Their laboratory evaluations demonstrated that EPNs can effectively induce mortality in both T. tabaci and the WFT, with Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) showing a significantly higher efficacy against T. tabaci. These findings suggest that S. feltiae may offer a more targeted option for managing onion thrips, particularly during the soil-dwelling pupal stages. Considering that T. parvispinus undergoes its prepupal and pupal stages within the plant substrate (Revynthi et al., 2024), evaluating EPNs using commercial strains and poured in similar substrates to those where ornamental plants are typically grown may provide valuable insights into the potential effectiveness of this biological control strategy.

As lethal endoparasites that naturally inhabit soil and epigeal environments, EPNs can infect a wide range of insects, particularly those that are soil-dwelling (Campbell et al., 2003), warranting studies on their potential to control the prepupal and pupal stages of T. parvispinus. The most used EPNs belong to the genera Heterorhabditis and Steinernema, which differ in their host-searching strategies. In general, Heterorhabditis species are active cruisers that move through the soil in search of hosts (cruisers), whereas Steinernema species tend to wait near the soil surface or ambush passing hosts (ambushers). However, behavioral variation occurs among species, forming a continuum between these two strategies (Campbell et al., 2003). Our study evaluated the potential of EPNs as biological control agents against T. parvispinus, addressing the need for sustainable pest management strategies in ornamental crop production. Commercially available EPNs from the genera Heterorhabditis and Steinernema were selected with the expectation that at least one species would exhibit potential efficacy under the typically warm climatic conditions of South Florida. We first assessed six EPN species under laboratory conditions: Heterorhabditis bacteriophora Poinar, Heterorhabditis indica Poinar, Karunakar & David (Rhabditida: Heterorhabditidae), Steinernema carpocapsae (Weiser), Steinernema kraussei (Steiner), S. feltiae, and S. riobrave Cabanillas, Poinar & Raulston (Rhabditida: Steinernematidae). In this initial phase, we tested their ability to infect the pest soil-dwelling prepupal and pupal stages of T. parvispinus using experimental arenas with a potting mix. Based on laboratory performance, four EPN species were selected for further evaluation in greenhouse trials using mandevilla plants (Mandevilla splendens (Hook.f.) Woodson), a species reported to be severely affected by the pest in commercial nurseries in South Florida.

2 Materials and methods

2.1 Plant material

Bean plants (Phaseolus vulgaris L. var. Roman; Goya Foods, Jersey City, NJ, USA) were used for insect colony maintenance and laboratory experiments. They were chosen instead of mandevilla as they allow faster and easier plant propagation and insect multiplication. Bean seeds were sown weekly in 140 mL plastic pots using a potting mix as substrate (ProMix BX Mycorhizae, Denver, CO, USA). Plants were watered three times per week. Since germination, planted pots were kept in a climate-controlled room set to 25 ± 2 °C, 50% RH, and a 12:12 h L:D photoperiod. The greenhouse trials used mandevilla plants (var. Scarlet) obtained from a local nursery in Homestead, FL.

2.2 Thrips parvispinus colony

A T. parvispinus colony was maintained in a containment facility of the University of Florida Tropical Research and Educational Center in Homestead, FL, under FDACS-DPI permit #2022-105. The colony was kept under controlled environmental conditions (27 ± 1 °C, 70% RH, 12:12 h L:D) on bean plants. This colony originated from individual thrips collected from mandevilla plants at a local nursery in Homestead, FL, as part of a diagnostic effort conducted in collaboration with the UF-TREC Plant Diagnostic Clinic and FDACS-DPI. The colony was maintained following the protocol described by Ataide et al. (2024), with no additional introduction of insects from other locations or collection dates due to quarantine restrictions. Under these conditions, inbreeding was managed by maintaining large populations of insects on both bean and pepper plants, and by dividing the colony into two separate population lines, which were reared in different rooms.

2.3 Nematode sources

Commercially produced nematodes were used in the experiments, including S. carpocapsae, S. feltiae, H. bacteriophora (BioBee, Salisbury, MD, USA), S. kraussei (BASF, Florham Park, NJ, USA), S. riobrave and H. indica (Arbico Organics, Oro Valley, AZ, USA). Upon arrival, infective juvenile nematodes (IJs) were stored at 9 °C for no longer than 2 weeks before use. Before application, nematodes were acclimated to room temperature, and viability was assessed by observing movement in three replicate samples of 100 IJs each. In all experiments, mean viability was ≥ 95%. Different batches of EPNs were used for each experimental trial.

2.4 Laboratory experiments

Adapting a method from previous research (Summerfield et al., 2024), the experimental arena was set using a plastic container (5 h ×5.5 d cm) (Fisherbrand, Waltham, MA, USA) with the lid adapted with an anti-thrips screen (mesh size: 54 µm) (Inoxia Ltda., Cranley, UK) to permit ventilation and avoid insect escape. Each container was filled with approximately 14.4 g of moisturized substrate (Promix, Premier Tech Ltd., Rivière-du-Loup, Quebec, Canada), which was gently pressed to ensure a depth of 2 cm in the substrate within the container (Figure 1A). In total, 600 g of sterile, non-sieved substrate and 1,250 ml of sterile water were used. Cohorts to obtain second-instar larvae of T. parvispinus individuals were prepared 6 days before the infestation day, as described in previous studies (Ataide et al., 2024). Ten second-instar larvae were placed on a 2.3 cm diameter bean leaf disk per container. After three days, the leaf discs were removed and inspected for dead or non-pupating larvae, which were subtracted from the initial number per container. Subsequently, 2 mL of either nematode solution or water (control) was pipetted evenly onto the substrate. The substrate surface area was 16 cm², and the EPN solution was approximately 3,200 infective juveniles (IJs). Therefore, the application rate was equivalent to approximately 200 IJs/cm². All counts and estimates were based on active IJs, so the viability of the products was considered to be approximately 100% at the time of inoculation.

Figure 1

Figure 1. Illustration of the methods used in testing the efficacy of EPNs against soil-dwelling stages of T. parvispinus under laboratory and greenhouse conditions. (A) EPNs were inoculated into arenas containing moistened substrate, and (B) surviving adult thrips were recovered one week later using a yellow sticky trap placed on top of the containers. Subsequent greenhouse trials were conducted using (C) mandevilla plants, and (D) surviving adult thrips were recovered 10 days after inoculation from the plants and adjacent yellow sticky traps. In both assays, infestations were established using second-instar thrips larvae placed on bean leaf discs.

One day after the nematode inoculation, a 5.5 yellow sticky card (Olson Products Inc., Medina, OH, USA) was cut to cover the lid of each container. Fifteen air holes were punched around the center of the card to allow for ventilation, while both glue sides of the sticky card trapped any thrips emerging from the substrate (Figure 1B). The sticky trap was attached to the upper side of the container, supported by three 3 cm toothpicks. The containers were stored in an incubator and maintained at 27 ± 1 °C, with a photoperiod of 12: 12h (dark: light) and 70 ± 10% RH for seven days, which is considered sufficient for the emergence of adult thrips under these environmental conditions (Hutasoit et al., 2017). Each container was inspected for emerging adults moving or trapped in the sticky cards. Ten replicates were executed for each EPN species and the control, which were completely randomized. All plastic containers were kept in a growth chamber (Panasonic Versatile Environmental Test Chamber MLR-352H) under controlled environmental conditions (27 ± 1 °C, 70% RH, 12:12 h L:D). The experiment was replicated twice (blocks), totaling 20 replicates per treatment, with the first replicate performed on October 30, 2024, and the second on December 13, 2024.

2.5 Greenhouse experiments

Mandevilla plants were individually placed in mesh cages (24.5 w ×24.5 d ×63 h cm, mesh diameter 160 µm; BD4F2260 Bugdorm^®, Taiwan) inside a greenhouse maintained at 27 °C ± 2 °C and 70 ± 10% relative humidity. Cages were arranged in a randomized complete block design to account for potential environmental variation within the greenhouse. Plants were irrigated once upon placement in the greenhouse, with no additional irrigation provided during the one-week observation period. Plants were manually infested with 50 second-instar larvae per plant from a synchronized thrips population in the colony. Larvae were transferred using a fine brush (Cotman, Winsor & Newton, London, England) onto bean leaf discs (1.4 cm diameter), cut with a cork borer (Fisherbrand, Pittsburgh, PA, USA). These discs were placed on 24-well cell culture plates (Falcon, Fisher Scientific, Pittsburgh, PA, USA), which were filled with water to prevent larval escape. Second instar larvae were released onto the plants by placing five leaf discs with 10 larvae on each plant, three days before application of EPNs (Figure 1C). These larvae were expected to pupate within approximately three to four days and remain as pupae for approximately one day; hence, the EPN application was timed to coincide with prepupal and/or pupal stages of the pest.

Nematode suspensions of H. bacteriophora, H. indica, S carpocapsae, and S. riobrave were prepared the same day of the application. The substrate surface area was 90 cm², and the EPN solution was approximately 9,000 infective juveniles (IJs). Therefore, the application rate was equivalent to approximately 100 IJs/cm², which was applied using a suspension of 20 mL, loaded into a 50 mL tube (Falcon, Thermo Fisher Scientific, USA). This rate was selected within the range of those used in greenhouse and field experiments against other similar pests (Arthurs and Heinz, 2006; Buitenhuis and Shipp, 2005; Cloyd and Herrick, 2021; Gulzar et al., 2021). It is important to note that EPNs manufacturers such as BASF and BioBee indicate a commercial application rate of approximately 50 IJ/cm². These species were selected based on their performance in the laboratory assays (see Results section). The suspensions were gently drenched into each plant pot, distributing the liquid evenly on the substrate. A yellow sticky card (7.5 cm width, 13 cm length) (Olson Products Inc., Medina, OH, USA) was set inside each cage the following day, secured in the plant’s soil (Figure 1D). Seven days after the application, the entire plant was sampled for adult thrips by removing and placing the whole plant into a plastic bag (Ziploc, San Diego, CA, USA). These samples were then examined in the laboratory, where they were vigorously shaken on top of a white paper to help visualize the adults. Only adult stages were recorded, including both alive and dead thrips. Ten days after product application, the yellow sticky cards were collected from the cages. Using a Leica S9E stereomicroscope (Leica, Heerbrugg, Switzerland), the number of adults trapped on the cards was counted. On the same day, a new yellow sticky card was placed in each cage, and three days later, the cards were collected again, and the number of adults trapped on them was recorded. Ten replicates were executed for each treatment, including the EPN species and a water control, which were distributed in a completely randomized design on a greenhouse bench. The experiment was conducted twice, with the first replicate performed on January 30, 2025, and the second on March 6, 2025.

2.6 Data analysis

Considering that the response variable (adult survival) across treatments in both laboratory and greenhouse experiments consisted of proportional data that did not meet the assumption of normality, we used a generalized linear mixed-effects model (GLMM), with a binomial error distribution that was fitted using the glmmTMB package in R (Brooks et al., 2017). The response variable was a two-column matrix of live and dead individuals, with the number of dead calculated as the difference between the initially infested second instar larvae and the number of recovered adults. The model included ‘Treatment’ as a fixed effect and ‘Replicate’ and ‘Block’ as random effects to account for variability between experimental replicates and blocks. Estimated marginal means (EMMs) (Lenth and Piaskowski, 2025) by treatment were calculated using the emmeans package, while pairwise comparisons (Tukey-adjusted, α= 0.05) between treatments were conducted.

3 Results

Treatment significantly affected the proportion of recovered T. parvispinus adults (χ² = 39.64; df = 6; P < 0.001) during the laboratory trials. One week after EPN inoculation, the mean proportion of adult survival in the water control treatment was 75%. In contrast, the proportion of recovered T. parvispinus adults in the EPN treatments ranged from 48% in H. bacteriophora to 67% in S. feltiae (Figure 2). The proportion of adult recovery in the water control was approximately 36% higher than in the H. bacteriophora treatment (P < 0.001, Figure 2). Similarly, recovery rates were significantly lower in the S. riobrave (31% less, P = 0.001), H. indica (25% less, P = 0.002), and S. carpocapsae (20% less, P = 0.032) treatments compared to the control, with no significant differences among these three treatments (H. bacteriophora/H. indica, P = 0.689; S. carpocapsae/H. bacteriophora, P = 0.230; S. carpocapsae/H. indica, P = 0.990).

Figure 2

Figure 2. Proportion of Thrips parvispinus adults (estimated marginal means) recovered one week after treatment with different entomopathogenic nematode species applied to a substrate, using 200 infective juveniles (IJs) per cm², compared to a water control, and under laboratory conditions. Boxes represent the interquartile range, horizontal lines indicate medians, whiskers show the data range, and diamonds indicate treatment means. Different lowercase letters indicate significant treatment differences (Tukey adjustment, α = 0.05).

Under greenhouse conditions, all EPN treatments significantly reduced the proportion of recovered T. parvispinus adults on artificially infested mandevilla plants (χ² = 118.52; df = 4; P < 0.001). Overall adult thrips survival in the control treatment was 26%, whereas the proportion of recovered adults in the EPN treatments ranged from 10.4% (S. riobrave) to 15.4% (H. bacteriophora) (Figure 3). The proportion of adults recovered in the water control was approximately 61% higher than in the S. riobrave treatment (P < 0.001) and 58% higher than in the S. carpocapsae treatment (P < 0.001), with no significant differences between these two EPNs (P = 0.979). This was followed by the H. indica and H. bacteriophora treatments, which each showed a reduction in the proportion of recovered adults of approximately 43% relative to the water control, respectively (H. indica/water control, P < 0.001; H. bacteriophora/water control, P < 0.001), with no significant differences between these two treatments (P = 0.999, Figure 3).

Figure 3

Figure 3. Proportion of Thrips parvispinus adults (estimated marginal means) recovered 10 days after treatment with different entomopathogenic nematode species drenched on mandevilla plant soil and using 100 infective juveniles (IJs) per cm², compared to a water control, and under greenhouse conditions. Boxes represent the interquartile range, horizontal lines indicate medians, whiskers show the data range, and diamonds indicate treatment means. Different lowercase letters indicate significant treatment differences (Tukey adjustment, α = 0.05).

4 Discussion

To the best of our knowledge, this is the first report demonstrating the efficacy of entomopathogenic nematodes against the invasive T. parvispinus. Based on preliminary observations and ongoing bioecological studies, T. parvispinus, like other related thrips pests, undergoes its prepupal and pupal stages in the soil (Revynthi et al., 2024). Considering this behavior, we evaluated the EPNs application in the soil and at a rate of 200 IJ per cm², a relatively intermediate rate based on other laboratory experiments (Ebssa et al., 2001), but that is four times higher than the commercial rate of 50 IJ/cm² recommended by manufacturers such as BASF and BioBee. As expected, thrips mortality in some species was greater than that of the control treatment, with the lowest survival observed in H. bacteriophora followed by S. riobrave > H. indica > S. carpocapsae. Notably, S. feltiae did not show differences with the control, contrary to our expectations and based on its demonstrated efficacy and subsequent use in controlling the WFT (Buitenhuis and Shipp, 2005; Ebssa et al., 2001).

Following the promising results obtained with four nematode species in laboratory trials, a dose of 100 IJs/cm² was tested under greenhouse conditions. This rate may be considered relatively low compared to those used in other greenhouse and field experiments against the WFT and the onion thrips, which typically range from 12.5 to 500 IJs/cm² (Arthurs and Heinz, 2006; Buitenhuis and Shipp, 2005; Cloyd and Herrick, 2021; Gulzar et al., 2021). Still, this rate was double the commercial rate recommended by some manufacturers as mentioned previously. All species tested showed reduced thrips survival across all EPN species compared to the control. It is worth noting that, although some studies have demonstrated the efficacy of EPNs against thrips under greenhouse conditions (Arthurs and Heinz, 2006; Buitenhuis and Shipp, 2005; Cloyd and Herrick, 2021; Gulzar et al., 2021), the level of control achieved is not always sufficient due to the low aesthetic damage thresholds in ornamental crops. For instance, when S. feltiae and Thripinema nickewoodi (Tylenchida: Allantonematidae) were applied in potted chrysanthemum, as foliar sprays combined with soil applications, they reduced WFT populations. The control, however, was insufficient to prevent aesthetic damage (Arthurs and Heinz, 2006).

Our trials were conducted under relatively constant environmental conditions, with an ambient temperature of 27 °C, which likely influenced the performance of the EPN species. This temperature represents the average temperature between March and August in southern Florida, with a range of 19 °C to 32 °C (Florida Automated Weather Network; https://fawn.ifas.ufl.edu), encompassing a significant portion of the growing and shipping season for ornamental plants. Considering the optimal ranges for S. riobrave (optimal temp.: 20 – 35 °C) (Jagdale and Grewal, 2003), H. bacteriophora (optimal temp.: 25 – 30 °C) (Chung et al., 2010), and S. carpocapsae (optimal temp.: 15 – 30 °C) (Jagdale and Grewal, 2003), it is reasonable to suggest that these species were well-suited for the environmental conditions of our trials, and hopefully for the conditions in southern Florida. In contrast, S. feltiae with an optimal temperature range of 5 – 25 °C (Jagdale and Grewal, 2003), is considered a cold-adapted species (Grewal et al., 1994a) and may have been at a disadvantage from the outset of our laboratory screening. Consistent with the above, high levels of field efficacy of S. riobrave against the emergence of plum curculio adults, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), were sustained under warm field conditions in a peach orchard in northern Florida following soil applications, whereas S. feltiae did not perform as well (Shapiro-Ilan et al., 2004).

In addition, our greenhouse experiments were designed to impose additional environmental constraints. As described in the materials and methods section, plants were irrigated only upon placement in the greenhouse, with no additional irrigation during the one-week observation period. Consequently, the only moisture available to the EPNs was the 20 mL carrier suspension applied during inoculation. Given that all tested EPN species are soil-dwelling organisms reliant on adequate soil moisture for survival and infectivity (Kaya and Gaugler, 1993), the combination of relatively high temperatures and low substrate moisture in the greenhouse likely influenced their performance. This context helps explain why S. riobrave, a warm-adapted nematode (Jagdale and Grewal, 2003) and S. carpocapsae, known for its tolerance to desiccation (Shapiro-Ilan et al., 2014), resulted in the lowest adult thrips recovery in the greenhouse trials. It is possible that other EPN species would perform differently under varying environmental conditions, warranting further research as T. parvispinus continues to expand its range into cooler climates or during seasons with milder temperatures in southern Florida (e.g., November to February).

Although the Florida Department of Agriculture and Consumer Services – Division of Plant Industry (FDACS-DPI) recently deregulated T. parvispinus as a quarantine species, with quarantine only applied to nurseries experiencing severe infestations (Ataide et al., 2025b), the continued spread of this pest remains a concern for the ornamental industry in the United States, as well as in Europe and Africa (Ahmed et al., 2025). Management currently relies on targeted pesticide applications, but challenges with resistance and incomplete control under heavy infestations are common. As demonstrated in this study, additional alternatives such as S. riobrave and S. carpocapsae offer new tools for integration into T. parvispinus IPM programs, particularly in southern Florida. Nonetheless, given that EPNs applications resulted in up to a 60% reduction in T. parvispinus survival, their sole use may not be sufficient to manage already heavy populations under the strict aesthetic thresholds required in the ornamental industry. Instead, EPNs may be best positioned as a preventive measure when scouting indicates that T. parvispinus populations are beginning to increase.

As T. parvispinus undergoes part of its development in the soil, EPNs have the potential to disrupt the life cycle by targeting soil-dwelling stages, which are typically protected from pest management tools targeting above-ground stages (Ataide et al., 2025a, Ataide et al., 2025b). Thus, the use of EPNs offers a strategic advantage by reducing the number of emerging adults, enhancing overall suppression, and reducing reliance on contact insecticides. Our findings suggest that some species are not only capable of parasitizing a relatively small host, such as T. parvispinus, but can do so under conditions of relatively high temperature and low moisture, as those implemented in our studies. Heterorhabditis bacteriophora and H. indica are both well known for their ‘cruiser’ foraging behavior (Grewal et al., 1994b; Kour et al., 2021), enabling them to actively search for less mobile hosts in the soil. In addition, S. riobrave displays a flexible search foraging strategy, combining both ‘ambusher’ and ‘cruiser’ behaviors, which allows it to target either mobile or sessile hosts. Notably, S. riobrave was discovered and characterized under the subtropical conditions of the Lower Rio Grande Valley of Texas (Cabanillas et al., 1994), suggesting its potential environmental adaptability to the conditions typical of southern Florida.

Factors such as the high cost of EPNs and their potential deterrent effects on grower adoption must also be taken into consideration. Additional research is needed to determine whether lower application rates can still provide effective control while improving the cost-benefit ratio. A more comprehensive analysis of the benefits of using EPNs should include their broad host range, as their application in ornamental systems may simultaneously suppress other economically important pests. For example, applications of S. carpocapsae targeting the hibiscus bud weevil Anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae) in tropical hibiscus, Hibiscus rosa-sinensis (Vargas et al., 2024), could also impact T. parvispinus populations, as hibiscus is a known host of T. parvispinus (Ahmed et al., 2023). Additional studies on biological control strategies are required, either individually or in combination, including predatory mites, predatory insects, and entomopathogenic fungi that target the soil-dwelling pupal and foliar feeding stages, respectively. Including extra options will improve the sustainability of the pest management program and reduce reliance on chemical interventions. In particular, repeated applications of entomopathogenic fungi such as Beauveria bassiana Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae), Metarhizium brunneum Petch (Hypocreales: Clavipitaceae), and Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae) against the chili thrips Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) under greenhouse conditions resulted in population reductions ranging from 62% to 94% (Arthurs et al., 2013), substantially higher than those observed in our EPN experiments, suggesting a potential for complementary mortality when these alternatives are combined. Although our study demonstrated the potential of EPNs in controlling T. parvispinus prepupae and pupae, their suppressive effect is limited to these developmental stages. Therefore, an IPM program for commercial nurseries should integrate additional control measures targeting larvae and adults that feed and hide on foliage and flowers. A rotation program using previously tested synthetic insecticides such as chlorfenapyr, abamectin, and spinosad (Ataide et al., 2025b), in combination with EPNs and entomopathogenic fungi, could help maintain pest populations under control while minimizing the risk of pesticide resistance development.

5 Conclusion

This study is the first report demonstrating the potential of entomopathogenic nematodes in controlling the invasive T. parvispinus. EPNs have the potential to disrupt the life cycle by targeting soil-dwelling stages, which are typically protected from pest management tools targeting above-ground stages. Our findings suggest that H. indica, S. carpocapsae, and S. riobrave are well adapted to parasitize the pest and have the potential to contribute to its control under the subtropical conditions of southern Florida. Although field trials were beyond the scope of the present study due to regulatory constraints, we acknowledge that evaluating the performance of these entomopathogenic nematodes under natural field conditions is an important next step to validate their efficacy and operational feasibility in IPM programs. The use of EPNs in the ornamental industry offers a strategic advantage by reducing the number of adults that emerge to infest the canopy, enhancing overall suppression, and reducing reliance on foliar sprays.

Author’s note

The findings and conclusions in this preliminary publication have not been formally disseminated by the U.S. Department of Agriculture and should not be construed to represent any Agency determination or policy. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA; USDA is an equal opportunity provider and employer.

Data availability statement

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Ethics statement

The manuscript presents research on animals that do not require ethical approval for their study.

Author contributions

GV: Investigation, Visualization, Formal Analysis, Validation, Data curation, Writing – review & editing, Conceptualization, Methodology, Writing – original draft, Supervision. LA: Writing – original draft, Investigation, Writing – review & editing, Data curation, Visualization, Methodology, Formal Analysis. YV-H: Writing – review & editing, Investigation, Methodology. MG: Writing – review & editing, Investigation, Methodology. AR: Investigation, Resources, Funding acquisition, Conceptualization, Supervision, Writing – review & editing, Project administration.

Funding

The author(s) declared that financial support was received for this work and/or its publication. This study was supported by the USDA-APHIS PPA7721 program (Fain # AP24PPQS&T00C135).

Acknowledgments

We thank Maria Alejandra Canon, Paola Villamarin, Isamar Reyes-Arauz, and Jorge Ramírez-Corona for technical support. We are also grateful to the FNGLA-Miami Dade Chapter, the Miami-Dade Farm Bureau, and the Thrips parvispinus growers task force for their support. We also thank Costa Farms for donating the mandevilla plants.

Conflict of interest

The authors declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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