Search Results (19)

The Asian hornet, Vespa velutina, is an invasive species that has not only expanded its range in Asia but has also invaded European countries, and it incurs significant costs on local apiculture. This phylogeographic study aims to trace the evolutionary trajectory of V. velutina and its close relatives; it aims to identify features that characterize an invasive species. The last successful invasion of Vespa velutina into France occurred in late May, 2002, and into South Korea in early October, 2002, which were estimated by fitting a logistic equation to the number of observations over time. The instantaneous rate of increase is 1.3667 for V. velutina in France and 0.2812 in South Korea, which are consistent with the interpretation of little competition in France and strong competition from local hornet species in South Korea. The invasive potential of two sister lineages can be compared by their distribution area when proper statistical adjustments are made to account for differences in sample size. V. velutina has a greater invasive potential than its sister lineage. The ancestor of V. velutina split into two lineages, one found in Indonesia/Malaysia and the other colonizing the Asian continent. The second lineage split into a sedentary clade inhabiting Pakistan and India and an invasive lineage colonizing much of Southeast Asia. This latter lineage gave rise to the subspecies V. v. nigrithorax, which invaded France, South Korea, and Japan. My software PGT version 1.5, which generates geophylogenies and computes geographic areas for individual taxa, is useful for understanding biogeography in general and invasive species in particular. I discussed the conceptual formulation of an index of invasiveness for a comparison between sister lineages. Full article

We assess the accuracy of geometric morphometrics (GMM) for determining the origin of insects of quarantine importance using the Asian hornet (Vespa velutina Lep.1836) as a case study. This species is highly variable, has an extensive natural distribution, and has been transported to many regions of the world. Forewing landmarks were applied to a large sample of regionally specific color morphs (previously considered “subspecies”) from across the species’ native Asian range. We reconfirm that GMM can statistically distinguish geographic variants independent of the color patterns that have heretofore been used for provenance, but which have been suspected of being unreliable. Almost all morphs in our analyses were statistically different except the centrally located V. v. variana, whose range lies between the continental V. v. auraria Smith, 1852, and V. v. nigrithorax du Buysson, 1905 morphs, and the Malaysian and Indonesian morphs. Even with moderate-sized training samples, discriminant function analysis (DFA) was able to classify geographic morphos with about 90% accuracy (ranging from 60% to 100%). We apply these results to determine the origin of a dead wasp recently intercepted in a mail parcel in Utah. Both DFA and continuous-trait maximum-likelihood clustering suggest that the Utah specimen belongs to the nigrithorax morph, which is native to southern China but now invasive in Europe, Japan, and Korea. These results are also supported by DNA barcode analysis, which groups the Utah individual with nigrithorax populations in South Korea and Japan. The relationship between variation in wing shape and genetic differentiation deserves further study, but molecular data are consistent with the GMM results suggesting that morphometric comparisons may be able to identify and provenance intercepted specimens quickly and inexpensively when molecular sequences and taxonomic specialists are unavailable. Full article

The yellow-legged hornet (Vespa velutina nigrithorax), outside its natural range, has become a major threat to domestic bees. Several control methods have been used to fight against V. velutina, but the results achieved are not satisfactory. The use of protein baits with biocides has shown to be an effective method to control invasive wasp populations, but they have not been used to control V. velutina. Thus, the efficacy of protein baits containing fipronil to reduce the presence of hornets in apiaries was evaluated in this study. After laboratory determination of the optimal efficacy of a protein bait at a 0.01% concentration of fipronil, field trials were conducted involving 222 beekeepers. The data reported by the 90 beekeepers who completed the requested questionnaire demonstrated that in the groups of apiaries with the highest pressure of hornets (groups with 10–30 and >30 hornets), there was a significant decrease in the presence of V. velutina, lasting at least two weeks. The reduction in the number of hornets was positively correlated with bait consumption, and bait consumption was positively correlated with the number of hornets present at the time of treatment. Although the method used has shown good efficacy and the concentration of fipronil used was very low; possible negative effects on the environment should also be evaluated. Full article

The Yellow-legged Hornet (Vespa velutina nigrithorax) (YLH) is an invasive insect that arrived in Europe in 2004 and is now spread across nine countries. It is a threat to the native entomofauna and harmful to beekeeping and agriculture, as it is a ravenous predator of the European Honey Bee (Apis mellifera) and other pollinating species. Its expansion has been unstoppable and all resources are needed to fight against it, including native vertebrate predators. Among these, the European Bee-eater (Merops apiaster) (EBE) is a potential one, but little is known about its predation on YLH. In a study carried out in Portugal, remains of YHL were detected in EBE nesting sites, which, to the best of our knowledge, is the first such report. This means that this bird could be one more agent in the biological control of this pest (although research on predation intensity is still needed), in conjunction with other natural predators and other strategies. In the Iberian Peninsula, both species are allopatric in vast regions, so the role of EBE may be more limited. However, in the rest of Europe, at a country or continent scale, the scenario may be different and sympatry may occur to a greater extent. Full article

Health risks caused by stings from Vespa velutina nigrithorax (VV), also known as the yellow-legged Asian hornet, have become a public concern, but little is known about its venom composition. This study presents the proteome profile of the VV’s venom sac (VS) based on Sequential Window Acquisition of all Theoretical Mass Spectra (SWATH-MS). The study also performed proteomic quantitative analysis and examined the biological pathways and molecular functions of the proteins in the VS of VV gynes (i.e., future queens [SQ]) and workers [SW]. The total protein content per VS was significantly higher in the SW than in the SQ (274 ± 54 µg/sac vs. 175 ± 22 µg/sac; p = 0.02). We quantified a total of 228 proteins in the VS, belonging to 7 different classes: Insecta (n = 191); Amphibia and Reptilia (n = 20); Bacilli, γ-Proteobacteria and Pisoniviricetes (n = 12); and Arachnida (n = 5). Among the 228 identified proteins, 66 showed significant differential expression between SQ and SW. The potential allergens hyaluronidase A, venom antigen 5 and phospholipase A1 were significantly downregulated in the SQ venom. Full article

The introduction and expansion of the Asian yellow-legged hornet (Vespa velutina nigrithorax) in Europe poses concern for multiple reasons, including biodiversity conservation. In addition to the predation of native insects (e.g., bees and wasps), this species may compete with native hornets due to an overlap of their climatic and trophic niches. The aim of this study is to investigate the realised climatic niche of V. v. nigrithorax and its response to climatic conditions and to evaluate the degree of overlap with the niches of the two native Vespa species present in Europe, Vespa crabro and Vespa orientalis. The niches of both native species partially overlap with the niche of the invasive species (Schoener’s D, 0.43 for V. crabro and 0.28 for V. orientalis), although some differences can be detected. V. crabro appears to be more adapted to cold and dry conditions than the invasive species, and V. orientalis is more adapted to arid climates. These differences may provide a competitive advantage to both native species in areas with a lower environmental suitability for V. v. nigrithorax, in the probable event that this species continues to spread, reaching all areas predicted to be suitable in Europe and in the Mediterranean basin. Full article

Invasive species become established in non-native areas due to their intrinsic characteristics and the ability to adapt to new environments. This work describes the characteristics of the nesting behavior of the invasive yellow-legged hornet (Vespa velutina nigrithorax) in Galicia (Northwest Spain). The first nest was detected in the area in 2012 and after that, the distribution pattern shows a species-invasion curve with slow progress at first but followed by rapid expansion. The nesting places for this hornet differ between the kinds of nests, while embryo nests are mainly found in buildings in spring, secondary nests are observed in vegetation in summer, autumn, and winter. The annual life cycle starts when the queen builds the embryo nests and starts to lay eggs. This leads to the emergence of the first workers, usually small in size, and sometimes a few males. After this stage, large nests called secondary nests are normally observed in most exposed sites. Relocation nests can also be observed; these are nests in the first stage of development presenting adults insects but without brood or meconium. The period of decline is characterized by the emergence of new queens and males, that are distinguishable even in the pupal stage, the appearance of two eggs per cell, and an irregular brood pattern. Full article

Vespa velutina is an invasive species that is currently the main concern for beekeeping in some areas of northern Spain. The hornet hunts honeybees to feed its larvae, stressing and weakening the honeybee colonies. To avoid losses of honeybee colonies, it is essential to investigate the pressure that is exerted by the yellow-legged hornet on apiaries and its consequences. In the present study, hives were monitored in an apiary that was situated in a high-pressure area of V. velutina during the years 2020 and 2021. The monitoring of environmental conditions of the apiary, the internal conditions of the colonies, and a hunting camera were used to relate the presence of hornets in front of the hives to the weather conditions in the apiary and the consequences caused on the colonies. The relationships between weather conditions and the hornet’s activity showed two types of hornet behavior. In the months of July and August, the maximum number of hornets appeared in non-central hours of the day. Meanwhile, in the months of September and October, the highest pressure in the apiary occurred in the central hours of the day, coinciding with temperatures between 15 °C and 25 °C and a relative humidity that was higher than 60%. The honeybee colony with the highest thermoregulatory capacity was the strongest and it was the key factor for the colony survival even when the hornet pressure was high too. Therefore, strengthening the hives and improving beehive health status is essential to avoid colonies decline. Full article

This study investigated the effects of wasp venom (WV) from the yellow-legged hornet, Vespa velutina, on scopolamine (SCO)-induced memory deficits in mice, as well as the antioxidant activity in HT22 murine hippocampal neuronal cells in parallel comparison with bee venom (BV). The WV was collected from the venom sac, freeze-dried. Both venoms exhibited free radical scavenging capabilities in a concentration-dependent manner. In addition, the venom treatment enhanced cell viability at the concentrations of ≤40 µg/mL of WV and ≤4 µg/mL of BV in glutamate-treated HT22 cells, and increased the transcriptional activity of the antioxidant response element (ARE), a cis-acting enhancer which regulates the expression of nuclear factor erythroid 2-related factor 2 (Nrf2)-downstream antioxidant enzymes. Concurrently, WV at 20 µg/mL significantly increased the expression of a key antioxidant enzyme heme oxygenase 1 (HO-1) in HT22 cells despite no significant changes observed in the nuclear level of Nrf2. Furthermore, the intraperitoneal administration of WV to SCO-treated mice at doses ranged from 250 to 500 µg/kg body weight ameliorated memory impairment behavior, reduced histological injury in the hippocampal region, and reduced oxidative stress biomarkers in the brain and blood of SCO-treated mice. Our findings demonstrate that WV possess the potential to improve learning and memory deficit in vivo while further study is needed for the proper dose and safety measures and clinical effectiveness. Full article

The yellow-legged Asian hornet (Vespa velutina Lepeletier 1836 (Hymenoptera: Vespidae)) is naturally distributed in China, Southeast Asia, and India; however, recently it has been detected outside of its native area, confirmed as being established in South Korea, Europe, and Japan. Health risks and deaths caused by the invasive Vespa velutina stings have become a public health concern, being the most common cause of anaphylaxis due to hymenopterans in some European regions. This in turn has led to increased demand from medical practitioners and researchers for Vespa velutina venom for diagnostic and therapeutic purposes. In this study, a straightforward, quick, and inexpensive method for obtaining Vespa velutina venom by electric stimulation is described. The venom extracts were analyzed by nuclear magnetic resonance spectroscopy (¹H-NMR). The availability of Vespa velutina venom will lead to improved diagnostic and therapeutic methods, mainly by venom immunotherapy (VIT), in patients allergic to this invasive species. Full article

The yellow-legged Asian hornet (AH) (Vespa velutina Lepeletier 1836 (Hymenoptera: Vespidae)) is naturally distributed in China, Southeast Asia, and India; however, it has been detected outside of its native area, confirmed as being established in South Korea, Europe, and Japan. Health risks and deaths caused by AH stings have become a public health concern. In the present work, a quick, straightforward, and inexpensive method for obtaining AH venom by electric stimulation is described. The availability of AH venom will lead to improved diagnostic and therapeutic methods, mainly by venom immunotherapy (VIT) in patients allergic to this invasive species. Full article

The introduction of invasive species is considered one of the major threats to the biodiversity conservation worldwide. In recent years, an Asian invasive species of wasp has set off alarms in Europe and elsewhere in the world, Vespa velutina. The Asian wasp was accidentally introduced in France around 2004 and shortly thereafter it was able to colonise practically all of Europe, including the Iberian Peninsula. The ecological and economic implications of V. velutina invasion and its high colonisation ability have triggered widespread trapping campaigns, usually supported by beekeepers and local governments, with the aim of diminishing its population and its negative impacts. Among the most used control methods are the capture traps, which use a sugary attractant to catch the invasive wasps. However, the species-specific selectivity and efficiency of these traps has been little studied. In this paper, we have analysed the specific identity of the unintentionally trapped insect species from northern Spain (covering one-year period), as well as we have assessed the provided ecosystem services by them. A total of 74 non-target taxa of insects were caught by the V. velutina studied traps, most of them correspond to the orders Diptera, Hymenoptera and Lepidoptera, the dipterans being the most abundant group. Surprisingly, the most abundant trapped species was the invasive fly, Drosophila suzukii that represented the 36.07% of the total catches. Furthermore, we reported the first record of ectoparasitic mites of the genus Varroa on V. velutina, constituting a newly recorded symbiotic association. Hopefully, the provided information helps to develop new protocols and management tools to control this invasive species in the Iberian Peninsula and other temperate areas of western Europe and the Mediterranean basin. Full article

The aim of this study was to compare the anti-inflammatory effect of wasp venom (WV) from the yellow-legged hornet (Vespa velutina) with that of bee venom (BV) on BV-2 murine microglial cells. WV was collected from the venom sac, freeze-dried, and used for in vitro examinations. WV and BV were non-toxic to BV-2 cells at concentrations of 160 and 12 µg/mL or lower, respectively. Treatment with WV reduced the secretion of nitric oxide and proinflammatory cytokines, including interleukin-6 and tumor necrosis factor alpha, from BV-2 cells activated by lipopolysaccharide (LPS). Western blot analysis revealed that WV and BV decreased the expression levels of inflammation markers, including inducible nitric oxide synthase and cyclooxygenase-2. In addition, WV decreased the nuclear translocation of nuclear factor κB (NF-κB), which is a key transcription factor in the regulation of cellular inflammatory response. Cumulatively, the results demonstrated that WV inhibited LPS-induced neuroinflammation in microglial cells by suppressing the NF-κB-mediated signaling pathway, which warrants further studies to confirm its therapeutic potential for neurodegenerative diseases. Full article

The recent introduction of the Asian yellow-legged hornet, Vespa velutina, into Europe has raised concern regarding the threat to honeybees and the competition with the European hornet, Vespa crabro. The aim of this study was to investigated essential (Mg, Fe, Zn, Cu) and non-essential (Cd and Pb) elements in these two species. Element concentrations were determined in the whole body and separately in the head, thorax and abdomen using atomic absorption spectrometry (AAS). The changes in essential element concentration and speciation during metamorphosis were also studied using size exclusion chromatography followed by AAS and proteomic analysis. In both species, the essential elements were more concentrated in the abdomen due to the presence of fat bodies. Magnesium, Fe and Zn concentrations were significantly higher in V. crabro than in V. velutina and could have been related to the higher aerobic energy demand of the former species required to sustain foraging flight. Low concentrations of Cd and Pb were indicative of low environmental exposure. The concentration and speciation of essential elements, particularly Fe, varied among the developmental stages, indicating a modification of ligand preferences during metamorphosis. Overall, the results in the present study provide a better understanding of the hornet metal metabolism and a foundation for additional studies. Full article

Vespa velutina is an invasive hornet that is colonising several countries worldwide, with detrimental effects on multiple components but primarily affecting honey bees and native insect species. Traps for wasps and hornets are commonly used for trapping V. velutina, both for monitoring and control purposes. In this study, we compared the performances of two typologies of traps and baits widely used for trapping this invasive hornet, by evaluating their effectiveness and selectiveness in trapping V. velutina in two sites during two different periods of the year, spring and autumn. The performance of the traps changed in relation to (i) the trap’s model, (ii) the bait’s typology and (iii) the period of the year. In spring, traps with common beer as bait were more effective and more selective independently of trap’s model than the commercial bait that has been tested. On the contrary, in autumn, just one combination of trap and attractant (the commercial trap and bait) achieved higher effectiveness and selectiveness. Despite the underlined variations among traps and baits, overall catches of V. velutina were scanty compared to bycatches of non-target insects, since best performing traps either in term of effectiveness and selectiveness caught 3.65% of the target species in spring and 1.35% in autumn upon the total trapped insects. This highlights the urgent necessity of developing more selective trapping methods for monitoring and particularly for controlling purposes. Full article