Species For Biological Control Research Articles

Assessment of the suitability of three native Trichogramma species for biological control of Tuta absoluta in China

Assessment of the suitability of three native Trichogramma species for biological control of Tuta absoluta in China

Altered biological control species interactions despite phenological synchrony along an urban–rural temperature gradient

Biological control programs provide simplified systems in which to investigate the influence of temperature on trophic interactions. We investigated the interaction between the invasive thistle Carduus nutans and its specialist herbivore, the biological control agent weevil Rhinocyllus conicus, along a temperature gradient spanning an urban-to-rural urbanization gradient in central Pennsylvania. As expected, more urbanized sites were warmer than rural sites. Nevertheless, C. nutans phenology was only slightly earlier at warmer sites, and the timing of observations of adult R. conicus on thistles did not shift earlier, leaving synchrony apparently unchanged. Despite unchanged phenological matching, seasonal patterns in weevil damage varied with temperature: early-appearing capitula at warmer sites were more heavily damaged than early capitula at cooler sites, yet overall a lower proportion of capitula was damaged at warmer sites. Rising temperatures may therefore reduce effectiveness of R. conicus for C. nutans control, as more capitula escape damage. Biological control systems and naturally occurring temperature gradients are useful systems in which to investigate climate change impacts, but a focus on the phenology of organisms’ presence or absence may not be sufficient; our study demonstrates that consideration of the interaction itself may be necessary.

Application of a Mechanistic Model to Explore Management Strategies for Biological Control of an Agricultural Pest

Despite the known benefits of integrated pest management, adoption in Australian broadacre crops has been slow, in part due to the lack of understanding about how pests and natural enemies interact. We use a previously developed process-based model to predict seasonal patterns in the population dynamics of a canola pest, the green peach aphid (Myzus persicae), and an associated common primary parasitic wasp (Diaeretiella rapae), found in this cropping landscape. The model predicted aphid population outbreaks in autumn and spring. Diaeretiella rapae was able to suppress these outbreaks, but only in scenarios with a sufficiently high number of female wasps in the field (a simulated aphid:wasp density ratio of at least 5:1 was required). Model simulations of aphid-specific foliar pesticide applications facilitated biological control. However, a broad-spectrum pesticide negated the control provided by D. rapae, in one case leading to a predicted 15% increase in aphid densities compared to simulations in which no pesticide was applied. Biological and chemical control could therefore be used in combination for the successful management of the aphid while conserving the wasp. This modelling framework provides a versatile tool for further exploring how chemical applications can impact pests and candidate species for biological control.

Parasitic wasps (Hymenoptera) and Biological Control in Chile: Applications and Potentials

Global biodiversity decline and pollution, along with climate change, directly threaten food security and sovereignty. Unsustainable practices in industrial agriculture, including the introduction of non-native insects exacerbate this environmental crisis. These can invade native habitats and disrupt the ecological balance, leading to biodiversity loss. We created a database of parasitic wasp species used for biological control in Chile, examining the percentage of introduced and native species, introduction timelines, and host interactions. A total of 73% of the Hymenoptera used for biological control in Chile are exotic species. This trend has grown over decades as new species were continuously introduced, resulting in an increasing accumulation of exotic species. We also identified instances of native and introduced parasitoid species sharing the same hosts, potentially causing a spillover effect. Given Chile's high endemism in its insect population, the massive introduction of exotic species could have detrimental consequences for local biodiversity and agricultural ecosystems. Overreliance on non-native pest controllers impedes the use of existing native biological control species, increasing vulnerability to pests adapted to widely used biological control agents. We advocate for prioritizing local and native parasitic wasps to ensure long-lasting, and sustainable agriculture production in Chile while mitigating the negative impacts of exotic species.

Native natural enemies of plant pests in Slovenia with an emphasis on species suitable for mass rearing.

In Slovenia, only the native natural enemies of plant pests that are on the EPPO Positive List of biological control agents can be used in agricultural production to control plant pests. The List of native species of organisms for biological control, which is an important part of the Regulations on biological control, currently includes a total of 35 species of beneficial insects and mites and entomopathogenic nematodes. Compared to the number of species on the first list that was established in 2006, the number of beneficial species that Slovenian growers of food and ornamental plants can currently use in everyday practice has doubled. This is the result of intensive professional and research work in the investigation of the occurrence and distribution of natural enemy species in Slovenia, which has been systematically supported by the state for many years. Natural enemy species, which are an integral part of the EPPO Positive List of biological control agents, can be included on the list of native biological control species via a special procedure. However, many natural enemy species that are not yet included on the EPPO Positive List have been identified in the period 2007-2022. In this paper, we list 75 such species and we present 5 candidates (Cotesia glomerata [L.], Diadegma semiclausum [Hellen], Anisopteromalus calandrae [Howard], Neochrysocharis formosa [Westwood] and Kampimodromus aberrans [Oudemans]) that, in our opinion, have high potential as biological controls and will be suitable in the future for mass rearing and use in augmentative biological control.

Entering, Linked with the Sphinx: Lysophosphatidic Acids Everywhere, All at Once, in the Oral System and Cancer.

Oral health is crucial to overall health, and periodontal disease (PDD) is a chronic inflammatory disease. Over the past decade, PDD has been recognized as a significant contributor to systemic inflammation. Here, we relate our seminal work defining the role of lysophosphatidic acid (LPA) and its receptors (LPARs) in the oral system with findings and parallels relevant to cancer. We discuss the largely unexplored fine-tuning potential of LPA species for biological control of complex immune responses and suggest approaches for the areas where we believe more research should be undertaken to advance our understanding of signaling at the level of the cellular microenvironment in biological processes where LPA is a key player so we can better treat diseases such as PDD, cancer, and emerging diseases.

Description of Neoseiulus hexaporus sp. nov. and a redescription of Neoseiulus mumai (Acari: Mesostigmata: Phytoseiidae) from Florida citrus groves

Abstract Predatory mites are effective natural enemies of small arthropods, including pest mites and insects, which provide biological control of several crop pests worldwide. The family Phytoseiidae (Acari: Mesostigmata) is a diverse group of predators found in cultivated crops and other habitats containing natural vegetation. Although some phytoseiid species are commercialized and widely used in biological control programs, the determination of natural populations and identification of the species is a vital first step in understanding their interactions with the crop, environment, and pests. The citrus crop is a diverse agroecosystem colonized by a variety of pests including mites and warrants an understanding of the complex of predators. We collected predatory mites from multiple citrus groves in Florida, to find and identify species for biological control in citrus crops. The examination of the specimens involved the use of Olympus CX-41 microscope, and drawings were prepared with the help of the attached camera Lucida. Any needed corrections were made using tracing paper, rapidograph pen, and Adobe Photoshop version CS6. Neoseiulus hexaporussp. nov. is described and illustrated as a new species based on its distinct morphology compared with previously described species in paspalivorus group. We also provide a complementary redescription of Neoseiulus mumai (Denmark), including an important diagnostic character of leg chaetotaxy which had led to the description of a new species, Neoseiulus kikuyu Ma, Fan & Zhang. We also provide new illustrations of N. mumai to facilitate its diagnosis.

Fungal consortium of two Beauveria bassiana strains increases their virulence, growth, and resistance to stress: A metabolomic approach.

The use of two or more microorganisms in a microbial consortium has been increasingly applied in the biological control of diseases and pests. Beauveria bassiana is one of the most widely studied fungal species in biological control, yet little is known about its role in fungal consortiums. In a previous study, our group found that a consortium formed by two strains of B. bassiana had significantly greater biocontrol potential against the polyphagous caterpillars Duponchelia fovealis (Lepidoptera: Crambidae) than either strain on its own. In this study, we use GC-MS and LC-MS/MS to evaluate and discuss the metabolomics of the consortium. A total of 21 consortium biomarkers were identified, corresponding to 14 detected by LC-MS/MS and seven by GC-MS. Antioxidant and anti-inflammatory mechanisms are the main properties of the metabolites produced by the consortium. These metabolites can depress the insect’s immune system, increasing its vulnerability and, hence, the fungal virulence of the consortium. In light of these results, we propose an action model of insect mortality due to the metabolites secreted by the consortium. The model includes the inhibition of defense mechanisms such as pro-inflammatory interleukin secretion, cell migration, cell aggregation, Dif, Dorsal and Relish gene transcription, and JAK/STAT and JNK signaling pathways. It also promotes the cleaning of oxidative molecules, like ROS, NOS, and H2O2, and the induction of virulence factors.

Predicting parasitoid accumulation by potential Brazilian peppertree biological control agents from assessments in the native and invaded ranges

During their initial releases, classical biological control agents may benefit from enemy-free-space as they are introduced to new habitats with relatively low attack rates by natural enemies. The benefits of classical biological control may be reduced by natural enemies that exploit new agents in the introduced range. Estimates of agent vulnerability to natural enemies prior to release could assist in predicting attack rates and prioritization of proposed agents. Additionally, release of vulnerable biological control agents could have unintended consequences that disrupt native food webs. Our goal was to predict the vulnerability of potential agents to attack by natural enemies by determining parasitism rates in the native range of the weed Brazilian peppertree, Schinus terebinthifolia. Furthermore, we conducted assessments of the rate of attack of ecological analogues in the invaded range in North America, where the agents are to be released, to assist in predicting post release vulnerability. Potential agents and analogues were assigned to four feeding niches, leaf folders, cryptic feeders, thrashers, and sap feeders. Cryptic members were generally most common in the invaded range. However, compared with the other niches, leaf folders were most common in at least one region of the native range. Surveys of potential agents of Brazilian peppertree in their native range of South America indicated parasitism rates were generally <20% for leaf folders (10.5 ± 6.3%; n = 485), cryptic feeders (17.6 ± 3.7%; n = 495), thrashers (12.1 ± 1.2%; n = 381), and sap feeders (2.5% ± 1.1%; n = 200). With exceptions, parasitism rates of the ecological analogues of North America were similar to those from South America for leaf folders (19.2 ± 7.9%; n = 19), cryptic feeders (16.5 ± 5.2%; n = 285), and sap feeders (0.2 ± 0.2%; n = 1247). Thrashers were not included in the analysis as a single parasitoid was found from few (n = 9) hosts recovered in North America. These results suggest that if species of these defoliating leaf folder or cryptic feeder niches are released for biological control in North America they will be parasitized at these same levels. However, if sap feeders are released, these results predict very low parasitism would result. These pre-release assessments of parasitism may assist in the prioritization of potential agent species for biological control of weeds and reduce the likelihood of indirect effects impacting native communities.

Citizen Science Meet South American Tachinids: New Records of Feather-Legged Fly Trichopoda (Galactomyia) pictipennis Bigot (Diptera: Tachinidae) from Chile.

The species of Gymnosomatini (Diptera: Tachinidae) are specialized to attack stink bugs (Hemiptera: Pentatomidae). Some of these flies, such as those in the genus Trichopoda Berthold, are conspicuous and represent target species to study with citizen science. Here we report for the first time the distribution range of T. (Galactomyia) pictipennis Bigot, a newly introduced biological control species of tachinid for use against stink bugs in Chile using data obtained through the citizen science method. Additionally, we update the distribution of T. arcuata (Bigot), a native biological control species of tachinid, and assess the grade of overlap between the flies and their main stink bug hosts. We obtained data regarding the occurrence of flies and stink bugs from the citizen science program "Moscas Florícolas de Chile," from Facebook groups, and from iNaturalist. We standardized our data to avoid temporal, spatial, and geographic biases. We report the extent of occurrence (EOO) and area of occupancy (AOO) for each fly and stink bug species. The EOOs for T. pictipennis and T. arcuata are 85,474 km2 and 20,647 km2 through central Chile ecosystems, respectively. The EOO of T. arcuata is overlapped by 53% with the introduced species. Trichopoda pictipennis has a high percentage of overlap with the EOO of Nezara viridula Linnaeus (61%), whereas T. arcuata has low percentages of overlap with different native Acledra species and with N. viridula. We discuss the potential of citizen science to detect (1) areas with higher diversity or gaps of occurrences, (2) new biological control agents, (3) prey records, (4) negative impacts on non-target species, (5) changes in composition at long-term, and (6) areas to promote conservation biological control in agricultural landscapes.

Artificial selection for nonreproductive host killing in a native parasitoid on the invasive pest, Drosophila suzukii.

Establishment and spread of invasive species can be facilitated by lack of natural enemies in the invaded area. Host‐range evolution of natural enemies augments their ability to reduce the impact of the invader and could enhance their value for biological control. We assessed the potential of the Drosophila parasitoid, Leptopilina heterotoma (Hymenoptera: Figitidae), to exploit the invasive pest Drosophila suzukii by focusing on three performance indices: (i) attack rate; (ii) host killing, consisting of killing rate and lethal attack rate (killing efficiency); and (iii) successful offspring development (reproductive success). We found significant intraspecific variation in attack rate and killing rate and lethal attack rate among seven European populations, but offspring generally failed to successfully develop from the D. suzukii host. We crossed these European lines to create a genetically variable source population and performed a half‐sib analysis to quantify genetic variation. Using a Bayesian animal model, we found that attack rate and killing rate had a heritability of h2=0.2, lethal attack rate h2=0.4, and offspring development h2=0. We then artificially selected wasps with the highest killing rate of D. suzukii for seven generations to test whether host‐killing could be improved. There was a small and inconsistent response to selection in the three selection lines. Realized heritability (hr2) after four generations of selection was 0.17 but near zero after seven generations of selection. The genetic response might have been masked by an increased D. suzukii fitness resulting from adaptation to laboratory conditions. Our study reveals that native, European, L. heterotoma can attack the invasive pest, D. suzukii and significantly reduce fly survival and that different steps of the parasitization process need to be considered in the evolution of host‐range. It highlights how evolutionary principles can be applied to optimize performance of native species for biological control.

Foraging aggressiveness determines trophic niche in a generalist biological control species

AbstractThere is a growing evidence that consistent interindividual differences in behavior, that is, behavioral types, can play an important role in key ecological processes such as predator–prey interactions, which in turn can have direct implications on biological control. Behavioral types of generalist predators may affect these interactions through individual differences in predators’ prey preferences and the breadth of predators’ trophic niches. This study examined how the multivariate nature of behavior, namely foraging aggressiveness, activity level, and risk-taking behavior, determines prey selection and trophic niche of the generalist agrobiont spider Philodromus cespitum. In laboratory experiments, we determined the repeatability of these behaviors and the preference between crickets, moths, fruit flies, and collembolans. We found that all three behaviors were moderately to strongly repeatable but there were no correlations between them, thus they did not form a behavioral syndrome. Only foraging aggressiveness influenced the prey selection of philodromid spiders and the more aggressive individuals had wider trophic niches because they incorporated prey that were more difficult to capture in their diet. In addition, more aggressive individuals killed a greater quantity of particular prey types while other prey types were killed at a similar rate by both aggressive and nonaggressive individuals. The differences in philodromids’ foraging aggressiveness, therefore, affected not only the overall prey density but also resulted in different prey community composition. As pest density and composition can both affect crop performance, further research needs to investigate how the interindividual behavioral differences of generalist natural enemies cascade down on the crops.

PcsR2 Is a LuxR-Type Regulator That Is Upregulated on Wheat Roots and Is Unique to Pseudomonas chlororaphis.

LuxR solos are common in plant-associated bacteria and increasingly recognized for playing important roles in plant-microbe interkingdom signaling. Unlike the LuxR-type transcriptional regulators of prototype LuxR/LuxI quorum sensing systems, luxR solos do not have a LuxI-type autoinducer synthase gene associated with them. LuxR solos in plant-pathogenic bacteria are important for virulence and in plant endosymbionts contribute to symbiosis. In the present study, we characterized an atypical LuxR solo, PcsR2, in the biological control species Pseudomonas chlororaphis 30–84 that is highly conserved among sequenced P. chlororaphis strains. Unlike most LuxR solos in the plant-associated bacteria characterized to date, pcsR2 is not associated with a proline iminopeptidase gene and the protein has an atypical N-terminal binding domain. We created a pcsR2 deletion mutant and used quantitative RT-PCR to show that the expression of pcsR2 and genes in the operon immediately downstream was upregulated ∼10-fold when the wild type strain was grown on wheat roots compared to planktonic culture. PcsR2 was involved in upregulation. Using a GFP transcriptional reporter, we found that expression of pcsR2 responded specifically to root-derived substrates as compared to leaf-derived substrates but not to endogenous AHLs. Compared to the wild type, the mutant was impaired in the ability to utilize root carbon and nitrogen sources in wheat root macerate and to colonize wheat roots. Phenazine production and most biofilm traits previously shown to be correlated with phenazine production also were diminished in the mutant. Gene expression of several of the proteins in the phenazine regulatory network including PhzR, Pip (phenazine inducing protein) and RpeA/RpeB were reduced in the mutant, and overexpression of these genes in trans restored phenazine production in the mutant to wild-type levels, indicating PcsR2 affects the activity of the these regulatory genes upstream of RpeA/RpeB via an undetermined mechanism. Our results indicate PcsR2 upregulates the expression of the adjacent operon in response to unknown wheat root-derived signals and belongs to a novel subfamily of LuxR-type transcriptional regulators found in sequenced P. chlororaphis strains.

Datat for: Foraging aggressiveness determines trophic niche in a generalist biological control species.

Datat for: Foraging aggressiveness determines trophic niche in a generalist biological control species.

Identification of main pathogenic Fusarium species for biological control of poppy plants in Afghanistan

Afghanistan is one of the major countries which contributes to illegal poppy (Papaver somniferum L.) cultivation, globally. The objectives of the present study were to report the Fusarium species associated with P. somniferum and to investigate a potential biocontrol agent against P. somniferum. A total of 155 Fusarium isolates were obtained from four provinces in Afghanistan, including Helmand, Kandahar, Daikundi and Bamyan. The pathogenic Fusarium spp. isolates were characterized by morphological and molecular identification, using the translation elongation factor-1α (TEF-1α) gene. The results of isolation revealed the most predominant species as F. proliferatum (27%), followed by F. equiseti (26%), F. solani (13%), F. incarnatum (12%), F. acuminatum (7%), F. oxysporum (5%), F. verticillioides (5%), F. pseudograminearum (2%) and F. coeruleum (2%). With the exception of F. oxysporum and F. solani, other identified species are the first reported Fusarium species associated with poppy plants in Afghanistan. Furthermore, pathogenicity testing of F. oxysporum, F. proliferatum, F. acuminatum and F. verticillioides isolates were performed. Although disease symptoms were observed in all species; F. oxysporum infected poppy samples showed an early development of wilt symptoms and their disease severity was significantly higher than all other isolates. The results suggest that F. oxysporum isolates have the potential to be used as biological control agents against poppy plants in Afghanistan.

The composition of soil-dwelling pathogen communities mediates effects on wireworm herbivores and wheat productivity

Greater natural enemy diversity generally increases prey mortality. Diversity can be beneficial when natural enemy species occupy distinct niches (complementarity effects) or when diverse communities contain the most impactful species by chance (identity effects). Most research assessing effects of natural enemy diversity focuses on aboveground predators, however, and few studies have assessed whether increased entomopathogen diversity in soil affects belowground herbivores. Here, we assessed effects of entomopathogen richness on herbivore suppression and plant productivity in a system consisting of entomopathogens, wireworm herbivores, and wheat plants. Specifically, in field experiments we varied the richness of four entomopathogen species (two nematodes, two fungi) that attack herbivorous Limonius californicus larvae belowground. We show that the presence of entomopathogens increased wireworm mortality and subsequently increased plant productivity, but a single entomopathogen species, Metarhizium brunneum, had stronger effects than other species (Beauveria bassiana, Heterorhabditis bacteriophora, and Steinernema carpocapsae). Moreover, entomopathogen communities with M. brunneum consistently produced the strongest effects on prey mortality and plant productivity. Our results suggest that diverse entomopathogen communities increased prey infection more than any single species, indicating complementarity occurred. However, increased plant productivity appeared to be driven by species identify effects. Our study shows that the composition of entomopathogen communities had stronger effects on a pest species than species richness, suggesting that careful selection of entomopathogen species for biological control may be more impactful than promoting entomopathogen diversity.

Biological Protective Effects Against Vibrio Infections in Grouper Larvae Using the Strombidium sp. NTOU1, a Marine Ciliate Amenable for Scaled-Up Culture and With an Excellent Bacteriovorous Ability

Bacterial infectious diseases cause a huge economic loss in aquaculture. Active biological control that uses bacterivorous organisms to remove pathogens is an ecologically friendly approach for the cultural system to counteract the bacterial infection. The ciliate is one of the main predators of bacteria in aquatic ecosystems, but whether it can be effectively adopted to protect aquaculture organisms from bacterial pathogens still remains to be investigated. In this study, we optimized the culturing method for a marine ciliate Strombidium sp. NTOU1 and analyzed its bacterivorous properties. Strombidium sp. NTOU1 could feed on a variety of bacteria including pathogenic species. By controlling the amount of frozen bacteria Erwinia spp. in the medium, the ciliate grew to the maximum density within 4 days and could reach 1.2 x 105 cells/mL after the suction filtration enrichment. Ingested bacteria were observed in the food vacuole of the ciliate, and the average bacterial clearance rate of a single NTOU1 cell was ~300 cells/hr. In the challenge trial which grouper larvae were exposed to an extreme environment containing a high density of the pathogen Vibrio campellii, only 33% of the grouper larvae could survive after 5 days. However, preincubating with Strombidium sp. NTOU1 for an hour resulted their survival rate to rise to 93%. Together, our results demonstrated that Strombidium sp. NTOU1 has the potential to become a biological control species to actively remove pathogens in aquaculture. In addition, the technical improvement to culture Strombidium sp. NTOU1 provides an advantage for this ciliate in the future academic research or biotechnological application.

Compatibility of two predator species for biological control of the two-spotted spider mite

Because predators may interfere with each other, an important step towards the implementation of successful release of multiple predators in biocontrol programs requires resolving how predators respond to the presence of heterospecific competitors. Several species of predatory mites are important biocontrol agents and the species Phytoseiulus macropilis and Neoseiulus californicus are used to control the two-spotted spider mite, Tetranychus urticae, an important pest in agriculture worldwide. We investigated their compatibility showing that the two predators do not avoid plants on which the other species is present together with their common prey, and demonstrated that their oviposition rates are not affected by the presence of the other species. However, the distribution of the eggs on leaf discs was affected by the presence of the heterospecific predator. This behaviour might weaken possible interference between these two biocontrol agents, which, in turn, may enable their persistence on plants and favour pest suppression. The increased joint use of several natural enemies for biological control highlights the importance of studies on predator–predator interactions.

The effect of biorational insecticides on the citrus aphids and their predator, Coccinella septempunctata L.

To determine selective effectiveness for specific pesticides on biological control species, we evaluated the contact toxicity of different treatments including 10 ml l-1 dishwashing liquid, Dayabon 5, 6, 7, 8, 9 and 10 ml l-1, Palizin 1.5, 2.5 and 2.5 ml l-1, Palizin 1.5, 2 and 2.5­+­Citrol oil 5 ml l-1, Tondoxir 2 and 3­+­Bartar soap 1 ml l-1, Malathion 2 ml l-1 and control (water) on the adult aphids of the most important citrus gardens and their predator, Coccinella septempunctata L. in the laboratory conditions. The results revealed that the Palizin treatment 2.5­+­Citrol oil 5 ml l-1, caused the highest rate of the mortality of the citrus green aphid, Aphis spiraecola Patch, 1914 in 36 hours. Concentrations of 7 to 10 ml l-1, Dayabon and Palizin 2.5­+­Citrol oil 5 ml l-1, as well as 3 ml-1 Tondexir + Bartar soap 1 ml-1 had the highest mortality of the citrus brown aphid, Aphis citricidus (Kirkaldy, 1907), 36 hours after treatment (100 %). In addition, the treatments of Palizin 2 ml-1­+ Citrol oil of 5 ml-1, as well as 2 ml l-1 Tondexir­+­Bartar soap 1 ml l-1 and concentrations of 5 ml l-1 and 6 ml-1 of Dayabon produced the same amount of the mortality of the citrus black aphid, Toxoptera aurantii (Boyer de Fonscolombe, 1841). Tondexir 3 ml l-1­+­Bartar soap 1 ml l-1 in 24 hours after treatment caused the highest rate of the mortality of the cotton aphids, Aphis gossypii Glover, 1877 (83.88 %). Malathion treatment caused a 100 % mortality of the predator ladybird 36 hours after treatment, while the lowest amount was observed in the Dayabon at 10 ml l-1 with 33.34 % mortality.

Coexistence of three specialist predators of the hemlock woolly adelgid in the Pacific Northwest USA.

The hemlock woolly adelgid (Hemiptera: Adelgidae: Adelges tsugae Annand) is an invasive insect, introduced from Japan to eastern North America, where it causes decline and death of hemlock trees. There is a closely related lineage of A. tsugae native to western North America. To inform classical biological control of A. tsugae in the eastern USA, the density and phenology of three native western adelgid specialist predators, Leucopis argenticollis (Zetterstedt), Le. piniperda (Malloch) (Diptera: Chamaemyiidae), and Laricobius nigrinus Fender (Coleoptera: Derodontidae), were quantified in the Pacific Northwest. Infested branches were collected from western hemlock (Pinaceae: Tsuga heterophylla (Raf.) Sarg.) at four sites around the Puget Sound, Washington and three sites in Oregon. Immature Leucopis were identified to species using DNA barcodes. Leucopis argenticollis was roughly twice as abundant as Le. piniperda. Laricobius nigrinus larvae were more abundant than the two species of Leucopis during the egg stage of the first adelgid generation, but Leucopis were present as feeding larvae during the second adelgid generation when La. nigrinus was aestivating in the soil, resulting in Leucopis being more abundant than La. nigrinus across the entire sampling period. Adelges tsugae and La. nigrinus densities were not correlated, while A. tsugae and Leucopis spp. densities were positively correlated. Leucopis spp. and La. nigrinus densities were negatively correlated. These results support the complementary use of La. nigrinus and the two Leucopis species for biological control of A. tsugae in the eastern USA, and point to the need for further investigation of spatial and temporal niche partitioning among the three predator species.