Predatory Beetles Research Articles

Crossbreeding and Backcrossing in the Pyrethroid-Resistant Ladybird Beetle Eriopis connexa (Germar) Determines Resistance in Offspring

The conservation of the predatory ladybird beetle, Eriopis connexa (Germar) after its release also relies on its resistance and the performance of its progenies. When resistant individuals are released or evolve in the field through mating with susceptible pairs, we anticipate that they will generate a resistant progeny, inheriting the resistance to lambda-cyhalothrin through an autosomal mechanism. The susceptibility of a field-collected population (EcGA) was characterized and determined by the performance of their progenies generated through mating with a resistant parent (EcViR). We paired virgin adults from the EcGA and EcViR populations, observing how their progenies developed, reproduced, and survived when exposed to dried lambda-cyhalothrin residues applied at field rates. Adults from the EcGA population were ~200-fold more susceptible than those of the EcViR population. Developmental times from larva to adult emergence for EcGA individuals were delayed by approximately 6 days and generated smaller adults compared to EcViR and their progenies. The egg production did not differ across parents and progenies, but females from EcGA and EcGA × EcViR progenies produced 130 more eggs in comparison to EcViR females during the 35-day evaluation period. Exposure to lambda-cyhalothrin resulted in 77.4 to 100% survival for adults from EcViR × EcGA progenies and EcViR parents, while EcGA and the population standard for susceptibility maintained in the laboratory (EcFM) did not survive the insecticide exposure. These findings indicate that field crosses between EcViR and EcGA will improve their progenies’ biological performance compared to the EcViR parents and will maintain a high lambda-cyhalothrin survival rate.

Short‐Term Grasslands in Agriculture Support Both Natural Enemy and Phytophagous Arthropod Populations

ABSTRACTSimplified agricultural land with high chemical input is increasingly replacing natural habitats in many parts of the world. This loss and fragmentation of natural areas may have profound impacts on an array of wildlife, including predatory arthropods that provide natural biocontrol of agricultural pests. There is increasing interest in utilising short‐term seminatural habitat restoration in agricultural systems to support populations of beneficial organisms. We assessed the impact of two types of short‐term set‐asides on the diversity and abundance/activity density of phytophagous and predatory arthropods. We found that flower‐enhanced set‐asides supported higher abundances of both phytophagous and predatory arthropods compared to control crop fields. In addition, we found that both set‐aside types (flower enhanced and traditional) supported a more active and diverse community of beneficial predatory carabid beetles, with particularly strong trends in set‐asides supplemented with flowering plants. These results suggest that small‐scale, temporary, seminatural habitats in agricultural systems provide support for a diverse and abundant community of both beneficial and phytophagous arthropods.

Ground beetle trophic interactions alter available nitrogen in forest soil

It is generally held that microbes exert primary control over nitrogen availability in temperate forests. Yet the role of soil and litter‐dwelling invertebrates to provide additional control via the breakdown of organic matter is an area of current exploration. Through trophic interactions within soil food webs, predators may indirectly affect prey with cascading effects on litter breakdown and nitrogen availability. The importance of these interactions, however, may be context‐dependent, varying with the stage of forest development and associated decomposer species composition given that young and old forests have vast differences in nitrogen availability, vegetation litter, soil properties and invertebrate functional groups. We examined ground beetle control over soil nitrogen and soil properties using a 68‐day mesocosm experiment that manipulated trophic structure (omnivore + predator beetles, predator beetles, and no beetles) in a young and old forest stand in the northeastern United States. In the young forest, net nitrogen mineralization decreased under predator + omnivore and the bulk soil C:N ratio in the old forest. However, we found no response in either forest context to the predator only treatment. Our study demonstrates the potential for ground beetles to strongly impact nitrogen availability and soil properties in forest ecosystems. Therefore, animal trophic interactions and their contexts must be included in our paradigm of nutrient cycles in temperate forests.

Functional diversity of ground beetles improved aphid control but did not increase crop yields on European farms.

Land-use intensification is often associated with a decline in functional diversity, potentially undermining the provision of ecosystem services. However, how changes in traits affect ecosystem processes remains poorly understood. Variation in trait values among species in a community may drive ecosystem processes. Alternatively, the mass ratio hypothesis proposes that trait values of the dominant species in a local community are related to ecosystem processes. Using data from 159 farms in six European countries, we quantified the impact of local and landscape-level land-use intensity on ground beetles as pest control agents. We then assessed the extent to which functional diversity and community-weighted mean trait values relate to pest control and cereal yield. In addition, we assessed how the responses to land use and the effects of different species on pest control and yield varied with their traits to compare the relative impact of the traits studied. Functional diversity of ground beetles improved aphid removal, but did not translate into higher crop yields. Pest control of aphids was enhanced by a higher proportion of smaller, mobile ground beetles with a preference for the vegetation layer. Smaller, predatory ground beetles in communities improved crop yield. The magnitude of responses to land-use intensification and the effects on pest control and yield were more strongly influenced by body size than other traits. Our study provides evidence that reduced management intensity can improve pest control by supporting small-sized, macropterous ground beetles. In contrast to the claims of ecological intensification, our joint analysis of the direct effects of land use on yield and indirect effects via functional diversity of ground beetles and pest control suggests that ecosystem services by ground beetles cannot compensate for the yield gap due to a reduction in land-use intensity.

Identifying insect predators using camera traps reveal unexpected predator communities in oilseed rape fields

Cameras are common tools for ecologists studying species abundance, richness, and interactions. They are mainly used to study large animals but are increasingly used to study invertebrates. Camera traps could be a powerful tool to identify and quantify the natural enemies, such as predators, of specific agricultural pests. This knowledge can then be applied to adapt farming practices to favour the predators identified and improve conservation biocontrol.Here, cameras were used to identify predators of two insect pests of oilseed rape (Brassica napus): the pollen beetle (Brassicogethes aeneus) and the brassica pod midge (Dasineura brassicae). These insects are spring pests of oilseed rape and are both susceptible to predation by ground-dwelling arthropods during their development cycle. The objectives of this study were to 1) identify the predators of the pest species, and 2) investigate the hypothesis that the diel activity periods of the predators match the timing of pest larval presence on the ground. Field observations were conducted in two locations over two consecutive years in the UK.In contrast to previous reports, our data collected using cameras showed that larval stages of predatory beetles are responsible for most of the predation events and that adult stages were not frequently observed feeding on the prey. Our data also showed that the traditional method, using pitfall traps, failed to detect the presence of large numbers of beetle larvae. Interestingly, the pests dropped to the ground and were therefore most susceptible to predation at the time when predators were most active.These results give new insight on the predators of the two most important spring pests of oilseed rape in Europe. This knowledge can be used by practitioners to develop framing practices targeted on enhancing the abundance of the larval stages of these beneficial arthropods to better control the pests in a more sustainable way.

Florida red scale, Chrysomphalus aonidum (Linnaeus, 1758) (Hemiptera: Diaspididae) in Morocco, infesting citrus orchards and an avocado tree

AbstractA study was conducted on citrus and avocado trees in north‐western Morocco between February 2023 and April 2024 to detect scale insects (Hemiptera: Coccomorpha) and their associated natural enemies. A total of 55 orchards in seven provinces were studied. The Florida red scale, Chrysomphalus aonidum (Linnaeus, 1758) (Diaspididae) was found on leaves at two sites: a moderate infestation in one citrus orchard and one specimen on an avocado tree. This work is the first record of the scale insect on avocado in Morocco, and the first morphological description of C. aonidum from the country, based on 100 adult females mounted on microscope slides. Chrysomphalus aonidum is not causing economic damage in citrus or avocado orchards in Morocco. Two ectoparasitoid wasps (Aphytis melinus DeBach and Aphytis sp.; Hymenoptera: Aphelinidae), and three predatory beetles (Rhyzobius lophanthae Blaisdell, Chilocorus bipustulatus Linnaeus, and Clitostethus arcuatus Rosso; Coleoptera: Coccinellidae), were found associated with C. aonidum on citrus leaves.

Trap Catches of Bark Beetle Predators Unaffected by the Ips Pheromone Lanierone in Southeastern United States1

Trap Catches of Bark Beetle Predators Unaffected by the <i>Ips</i> Pheromone Lanierone in Southeastern United States1

Population genomics and demographic modeling enhance our understanding of trophic level interactions in biological control

In this paper, we focus on the application of population genomics, including next-generation sequencing and demographic modeling, to enhance the understanding of historical and contemporary trophic level interactions that are a fundamental basis of biological control. We outline how the integration of ecological approaches with population genomics and demographic modeling can provide additional insights into existing trophic interactions and how natural enemies, their parasitoids, and pest species evolve through these interactions, potentially affecting future levels of biological control. We briefly review and summarize our recent population genomic studies of predatory ladybird beetles and discuss how our results provide guidelines for the use of population genomics techniques and population demographic modeling to enhance our understanding of trophic level interactions. Our intent is to demonstrate as a proof of concept, how these methods can supplement currently used techniques and add a complementary genomic aspect to ecological understandings of trophic level interactions, including estimates of effective population sizes of natural enemies and pest species, examination of correlations between these effective population sizes, and evolutionary changes in natural enemies and pest species which may influence levels of biological control. This in combination with experiments and simulations provide a well-rounded framework for using population genomics to inform multi-tier trophic level interactions.

Biological Control Options for the Management of Tadpole Shrimp (Triops longicaudatus (LeConte)) in California Rice

Tadpole shrimp (Triops longicaudatus) has become a major pest for California rice farmers. Currently, management relies solely on the insecticide lambda-cyhalothrin. However, resistance to this pyrethroid was confirmed in 2016; thus, identifying an effective and practical biological control method for TPS is a priority. Field trials were conducted from 2017 to 2018 to (1) evaluate the efficacy of the predatory fish Gambusia affinis and the predatory beetles, Laccophilus maculosus (Say) and Tropisternus lateralis (Fabricius), in controlling TPS, (2) test the efficacy of several inoculation rates of Gambusia affinis at controlling TPS and (3) to explore early indicators of TPS activity and damage as monitoring tools. Both Gambusia affinis and the predatory beetle treatments were not significantly different from the commercial standard (lambda-cyhalothrin). Both four and five Gambusia per 1 m2 controlled TPS as well as lambda-cyhalothrin, and we observed that Gambusia affinis was able to reproduce in the field. Water turbidity was significantly correlated with TPS counts (R = 0.85, N = 20, p &lt; 0.0001 (2017); R = 0.58, N = 30, p = 0.0007 (2018)). The number of dislodged seedlings was less reliably correlated with TPS count; in 2017, correlations were significant (R = 0.84, N = 20, p &lt; 0.0001); however, in 2018, correlations were not significant (R = 0.18, N = 30, p = 0.35). With further refinement, water turbidity could play a valuable role in monitoring TPS populations.

Navigating challenges in the management of Dactylopius opuntiae (Cockerell): Transitioning from ’introduction biological control’ to a preemptive strategy of artificial seeding of a natural enemy

The invasion of false carmine cochineal Dactylopius opuntiae (Cockerell) (Hemiptera; Dactylopiidae) in the Mediterranean region presents a serious threat to cactus pear cultivation. The cochineal was first identified in Israel in 2013, and it soon became clear that biological control is the only long-term solution to protect the cactus pear Opuntia ficus-indica. Releases of the introduced predatory beetle Hyperaspis trifurcata Schaeffer (Coleoptera; Coccinellidae) began in 2016, demonstrating high efficacy and leading to a decline in cochineal populations and plant survival. While H. trifurcata can autonomously reach new cochineal hotspots, it often arrives too late to prevent substantial damage to cactus pear. Human intervention is therefore necessary to expedite the predator’s establishment in new infested sites. To facilitate the spread of the beetle, we consider two approaches: transferring beetle seeding stocks from northern locations through a volunteer network organized by the research team, and applying the ’predator – prey dual introduction’ concept to preemptively mitigate new hotspots expected to emerge as the cochineal spreads southward via winds or birds. These activities have led to a major decrease in the rate of spread of the cochineal population in the East Mediterranean, and in the damage that it inflicts to cactus pear hedgerows. Implementing a similar approach in North Africa can prevent or slow the spread of the cochineal to the northern coast of the central Mediterranean and avoid the heavy damage experienced in Morocco.

Bacterial communities varied in different Coccinella transversoguttata populations located in Tibetan plateau

Coccinella transversoguttata is an important predatory beetle in Asia and America. Currently, few studies have investigated C. transversoguttata in China especially in the Tibetan plateau. In this study, full-length 16 s rRNA sequencing and qPCR experiment were performed on eight C. transversoguttata populations collected from Tibet to analyze their bacterial communities and bacteria abundance. In summary, our results revealed the microbial compositions, diversities and bacterial titers in the bacterial communities in C. transversoguttata populations in the Tibetan plateau. In future, there is a need to explore the differences in microbiota among various C. transversoguttata populations collected from different locations. These results add to our understanding of the complex bacterial communities of C. transversoguttata and their utilization as potential biocontrol factors.

An enhanced lure for eastern populations of the North American spruce beetle, Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae).

Regional variation in pheromone production and response has practical implications for the use of semiochemical lures to monitor and control bark beetle populations. We tested 4 lure formulations including 2 new formulations that reflect the pheromone production profiles of western and eastern populations of spruce beetles, Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae), as well as 2 commercially available formulations (current Rocky Mountain lure and current Atlantic lure), in 2 locations in New Brunswick, Canada. In 2 separate years, the new eastern lure containing seudenol, MCOL, and spruce terpenes captured 4 times (2021) and 11 times (2022) more spruce beetles than the current Atlantic lure that consisted of frontalin, seudenol, and spruce terpenes. In 2021, we also captured more eastern larch beetles, Dendroctonus simplex LeConte (Coleoptera: Curculionidae), with the new eastern lure, whereas in 2022, we captured the most D. simplex with the current Atlantic lure, suggesting that more research is needed on D. simplex pheromone production and response across its range. The bark beetle predator, Thanasimus dubius (Fabr.; Coleoptera: Cleridae), did not respond well to the new eastern blend that lacks frontalin, suggesting that response to frontalin is important in finding prey and might be conserved in predator populations. The reduced trap catch of T. dubius to the enhanced lure is beneficial because it does not inhibit natural population control by removing predators from the community. Our study reveals an improved trap lure for eastern populations of spruce beetles and highlights gaps and research needs in bark beetle pheromone ecology.

Enantiomeric composition of α-pinene affects catches of bark and wood boring beetles, and associated species, in ethanol-baited multiple-funnel traps.

In 2009, we determined the effects of the enantiomeric composition of the kairomone, α-pinene, on trap catches of arboreal beetles (Coleoptera) in stands of eastern pine trees with resin dominated by (+)-α-pinene. We hypothesized that the responses of beetles would correlate with the predominant enantiomer of α-pinene found in host pines. Lures of (+)-, racemic (±), and (-)-α-pinene were added separately to ethanol-baited multiple-funnel traps. Species such as Monarthrum mali (Fitch), Dendroctonus terebrans (Olivier), Ips grandicollis (Eichhoff), and Pachylobius picivorus (Germar) (Coleoptera: Curculionidae) showed a preference for traps co-baited with (-)-α-pinene. α-Pinene enhanced attraction of Hylastes salebrosus Eichhoff, Hylastes porculus Erickson and Hylastes tenuis Eichhoff (Coleoptera: Curculionidae) to ethanol-baited traps with no effects from enantiomeric composition of α-pinene. The attraction of the ambrosia beetles, Xyleborinus saxesenii (Ratzeburg) and Dryoxylon onoharaense (Murayama) (Coleoptera: Curculionidae) to ethanol-baited traps was interrupted by the addition of α-pinene, regardless of enantiomeric composition. Species such as Xylosandrus germanus (Blandford), Cnestus mutilatus (Blandford) and Stenoscelis brevis (Boheman) (Coleoptera: Curculionidae) were unaffected by the presence of α-pinene. Trap catches of some species of longhorn beetles and bark beetle predators (Coleoptera: Cerambycidae, Cleridae, Elateridae, Histeridae, and Trogossitidae) were increased by the addition of α-pinene, although results varied by location. Platysoma spp. (Coleoptera: Histeridae) showed a marked preference for traps co-baited with (+)-α-pinene in Florida and Georgia. In summary, we found that the enantiomeric composition of α-pinene in hosts was not a good predictor of enantiomeric preferences by beetles.

Trait-environment interactions of saproxylic beetles as a guide to biodiversity conservation strategies

Conservation of biodiversity requires in-depth knowledge of trait-environment interactions to understand the influence the environment has on species assemblages. Saproxylic beetles exhibit a wide range of traits and functions in the forest ecosystems. Understanding their responses to surrounding environment thus improves our capacity to identify habitats that should be restored or protected. We investigated potential interactions between ecological traits in saproxylic beetles (feeding guilds and habitat preferences) and environmental variables (deadwood, type and age of surrounding forest). We sampled beetles from 78 plots containing newly created high stumps of Scots pine and Silver birch in boreal forest landscapes in Sweden for three consecutive years. Using a model based approach, our aim was to explore potential interactions between ecological traits and the surrounding environment at close and distant scale (20 m and 500 m radius). We found that broadleaf-preferring beetle species are positively associated with the local broadleaf-originated deadwood and broadleaf-rich forests in the surrounding landscapes. Conifer-preferring species are positively associated with the local amount of coniferous deadwood and young and old forests in the surrounding landscape. Fungivorous and predatory beetles are positively associated with old forests in the surrounding landscapes. Our results indicate that both local amounts of deadwood and types of forests in the landscape are important in shaping saproxylic beetle communities. We particularly highlight the need to increase deadwood amounts of various qualities in the landscape, exempt older forests from production and to increase broadleaf-rich habitats in order to meet different beetle species’ habitat requirements. Trait responses among saproxylic beetles provide insights into the significance of broadleaf forest and dead wood as essential attributes in boreal forest restoration, which helps conservation planning and management in forest landscapes.

Shared patterns of population genomic variation and phenotypic response across rapid range expansions in two invasive lady beetle species

Non-native lady beetle species have often been introduced, with variable success, into North America for biological control of aphids, scales, whiteflies, and other agricultural pests. Two predatory lady beetle species, Propylea quatuordecimpunctata and Hippodamia variegata, both originating from Eurasia, were first discovered near Montreal, Quebec, in North America in 1968 and 1984, respectively, and have since expanded into northeastern North America and the midwestern United States. In this study, we estimate the range-wide population structure, establishment and range-expansion, and recent evolutionary history of these lady beetle species using reduced-representation genotyping-by-sequencing via ddRADseq. In addition, we quantified the responses to a key abiotic factor, photoperiod, that regulates adult reproductive diapause in these two species and may influence their geographical range in North America. Our analyses detect: (1) non-significant genetic differentiation and divergence among North American populations that likely originated from a single accidental introduction, (2) evidence of reduced contemporary gene flow within the continental US, and (3) minor phenotypic differences in diapause induction between populations of the two species from the same location.

Ground beetle movement is deterred by habitat edges: a mark-release-recapture study on the effectiveness of border crops in an agricultural landscape.

Border crops can increase beneficial insect biodiversity within agricultural fields by supplementing insects with food and nesting resources. However, the effectiveness of border crops relies on insect movement between adjacent habitats and some insects might consider habitat boundaries as barriers. Therefore, understanding insect movement between habitats is needed to determine the effectiveness of border crops for ecosystem services such as pest control within agricultural habitats. Our objective was to compare ground beetle (Coleoptera: Carabidae) movement across soybean plots that were bordered by corn and grassland habitat to determine whether habitat boundaries were considered barriers of movement to predatory beetles. Using a grid of pitfall traps within these habitats, we conducted a mark, release, and recapture experiment to track and evaluate ground beetle movement patterns. We found that ground beetles stayed in the habitat of their release and that movement between habitats, despite the type of bordering habitat or type of edge, was uncommon. We also found that long-distance movement was rare as most beetles moved less than 5 m (regardless of release or recaptured habitat) and movement was perpendicular to habitat edges. These results suggest that any edge habitat, including agricultural-agricultural boundaries and natural-agricultural boundaries, are likely barriers to ground beetle movement. Therefore, in order for border crops to be effective in pest management by ground beetles, making habitat edges more permeable, especially using techniques such as edge softening, could promote cross-habitat movement and ultimately contribute to natural pest control in agricultural systems.

Developing an improved lure for attracting the pine sawyer beetle (Monochamus galloprovincialis) with reduced bycatch of predatory beetles

Abstract The pine sawyer beetle (Monochamus galloprovincialis) is a European vector of the invasive pinewood nematode (Bursaphelenchus xylophilus), one of the most dangerous threats to pine forests worldwide. One recommended method for detecting the nematode is catching and inspecting the M. galloprovincialis beetles. Effective commercial lures are available for that insect but attract non‐target species, particularly beneficial Thanasimus species. Our study aimed to develop an equally effective M. galloprovincialis lure less attractive to beneficial predatory insects. We used electroantennography to test several compounds occurring in the pheromones, hindgut extracts or headspace emissions of non‐Ips bark beetles. The compounds that caused the strongest antennal responses were used along with α‐pinene (host‐tree volatile) and monochamol (2‐undecyloxy‐1‐ethanol, a male‐produced aggregation pheromone of M. galloprovincialis) to prepare the lures for olfactometric and field testing. In the field experiments, the lure containing (+)‐α‐pinene, monochamol, (1R)‐(−)‐myrtenal and (S)‐(−)‐trans‐verbenol was equally effective as the commercial lure Galloprotect Pack. It attracted significantly less Thanasimus formicarius and T. femoralis beetles. Thus, the new lure can serve as a basis for developing an operational lure for monitoring M. galloprovincialis with reduced bycatch of predatory beetles.

Artificial diets can manipulate the reproductive development status of predatory ladybird beetles and hold promise for their shelf-life management

With the development of biological control methods, the predatory ladybird beetle Harmonia axyridis Pallas (Coleoptera: Coccinellidae) has been widely used for pest control in agricultural production. Appropriate shelf-life management strategies could synchronize H. axyridis production with pest outbreaks, finally improving the effectiveness of biological control. Herein, we preliminarily explored whether an artificial diet could optimize the shelf-life management of H. axyridis. We compared the survival rate, nutrition accumulation, reproductive development, juvenile hormone (JH) related-gene expression levels, and stress resistance gene expression levels between aphid-fed and artificial diet-fed H. axyridis females. The results revealed that H. axyridis females maintained a high survival rate after being fed an artificial diet for 60 days, whereas the survival rate of aphid-fed females decreased. Continuous feeding of the artificial diet caused H. axyridis females to enter a diapause-like state, which was characterized by low JH levels, high triglycerides and trehalose accumulation, ovarian development inhibition, decreased Vgs expression levels, and increased stress resistance gene expression levels. This diapause-like state could be promptly recovered upon transferring to an aphid diet. These results indicate that the artificial diet could manipulate the reproductive development status of H. axyridis and lay the foundation for its shelf-life management.

Edge history modulates the depth of edge influence: Evidence from ground beetles with different feeding traits

Anthropogenic habitat loss and fragmentation are major concerns to conservationists, since these processes lead to species decline and extinction. Edge effect is one of the most important causes of biodiversity losses in fragmented habitats. The depth of edge influence, the distance over which the edge effect penetrates into the adjacent habitat is a central issue, as it fundamentally determines whether the habitat fragment has any remaining core habitat, which is essential for the survival of habitat specialist species. We reviewed 204 edge studies on ground beetles (Coleoptera: Carabidae) of different feeding habits, in forests, one of the habitats most impacted by humans. Meta-analysing 1814 abundance data of 351 ground beetle species from forest edges and their adjoining interiors, we showed that forest edges had significantly higher abundance of herbivorous, omnivorous, and predatory ground beetles than their interiors. Edge history considerably affected the depth of edge influence which on all trophic groups was similar in natural edges and those maintained by agriculture (≤ 10–20 m), while it was wider (> 300 m) when created by forestry or other anthropogenic activities. Consequently, the minimum area of a forest fragment should be ∼ 330 ha in order to keep half of it as core habitat to preserve forest-interior species.

Verbenone Affects the Behavior of Insect Predators and Other Saproxylic Beetles Differently: Trials Using Pheromone-Baited Bark Beetle Traps.

In our study, we assessed the effects of verbenone, the most widely studied bark beetle aggregation inhibitor, on saproxylic beetles in a Mediterranean pine forest in Tuscany. Verbenone pouches were devised in the laboratory and then applied to Ips sexdentatus pheromone traps so that their catches could be compared to those of traps containing just the pheromone. The trial was carried out in spring-summer 2023, and insect catches were collected every two weeks. A total of 9440 beetles were collected that belonged to 32 different families and 57 species. About 80% of the captures were bark beetles, mainly Orthotomicus erosus. Beetle predators accounted for about 17% of the captures, with a total of 12 species. Some of these predator species had not yet been studied in relation to verbenone effects, like other saproxylic beetles recorded in this study. A significant reduction in captures was recorded for some beetles (e.g., I. sexdentatus and O. erosus), while for other species, no differences emerged, and in some cases, captures increased significantly when verbenone was present in the traps (i.e., Hylurgus ligniperda, Corticeus pini, and Aulonium ruficorne). The diversity of caught saproxylic beetles increased significantly in the verbenone traps, highlighting possible implications of the use of verbenone when managing bark beetle outbreaks.