Vespa crabro – biology and interactions with honey bee colonies
Scientific review
Preface
The European hornet, Vespa crabro Linnaeus, 1758, is a eusocial vespid native to much of Eurasia and a generalist predator of arthropods. Apis mellifera is among its possible prey. The relationship between the two species depends on the hornet’s social biology, the strength of the honey bee colony and the strongly seasonal hornet life cycle [1,2].
The implications for beekeeping become more pronounced in the second half of the year, when a colony of V. crabro reaches its largest size, its brood needs more protein, and it produces reproductive individuals [2]. Hornets mainly intercept bees outside the hive. Colonies of A. mellifera can mount collective defences, including balling [1].
Food baits can help monitor hornets, but they may also concentrate them locally and increase encounters around an apiary. Researchers have therefore explored systems in which an insect carries a substance into its own colony. This approach, known as trophic transfer or a Trojan horse approach, draws on food collection, prey processing and trophallaxis [3].
Most of the experimental evidence concerns Vespa velutina. Studies have examined protein baits containing fipronil and, more recently, the oral toxicity of acetamiprid, spinosad, cypermethrin and natural pyrethrins [4,5]. Analytical work has also detected the fipronil metabolites fipronil sulfone and fipronil sulfide in larvae. This raises the research question of whether metabolism in the target species could influence the effect of low doses [6].
These findings cannot be assumed to apply to V. crabro. The European hornet has a different ecology, and control research needs to account for its role in ecosystems. Future studies of baits should focus on behavioural and pharmacological selectivity, examining species-specific attractants, suitable food matrices, social transfer, and compounds that maximise effects on the target while limiting risks to other organisms.
1. Introduction
The presence of Vespa crabro in apiaries is often described simply as hornets eating bees. Several aspects of its biology shape the interaction.
V. crabro is a generalist predator. Its diet includes many arthropods and plant resources, and honey bees are one component [2]. Its colonies are annual and strongly seasonal. A founding queen starts a nest in spring. The colony grows through summer and reaches its largest size in late summer and autumn. Workers and males die at the end of the cycle, while the new queens overwinter individually [2,7].
For beekeeping, the number of hornets present is only one part of the picture. The stage of the hornet colony’s development and the vulnerability of the honey bee colony also matter.
The hornet’s social behaviour is also relevant. Workers capture and process prey and carry food back to the nest. This colony food network offers a route to study control methods that work differently from trapping alone [3].
2. Biology of Vespa crabro
2.1. Colony life cycle
A colony of V. crabro lasts one season. The population persists through the mated females produced late in the season, which found new nests after overwintering [2,7].
It helps to distinguish three biological entities:
the nest, a temporary structure;
the colony, a social group that lives for one season;
the population, which persists through future queens.
An abandoned nest is therefore no indication that a new colony will occupy it the following year.
2.2. Spring nest founding
The season begins with a queen that has survived the winter. At first, she builds the first cells, lays eggs and gathers food on her own.
This founding stage differs from life in a mature colony. There are few individuals, and the whole reproductive investment depends on a single queen.
The division of labour changes rapidly once the first workers emerge. They gradually take over foraging, leaving the queen to concentrate on egg laying [2].
2.3. Summer growth
The colony grows rapidly in summer. Workers forage, care for the brood, maintain the nest and defend it.
Adults and larvae have different dietary needs:
adults rely mainly on liquid, sugar-rich foods;
the brood needs protein-rich food derived from animal prey [2].
The colony therefore forages for two kinds of food.
Hornets can gather carbohydrates for adults and hunt prey to feed the brood.
2.4. Late summer and autumn
The colony needs more food as it grows. Towards the end of the cycle, it produces new queens and males.
Observations in Sardinia documented foraging on fruit, flowers, plant exudates, water and a range of prey, including A. mellifera [2].
Late summer and autumn are therefore the periods when V. crabro may be most conspicuous to beekeepers.
2.5. Overwintering
Workers and males die at the end of the season. The newly mated females leave the nest and seek sheltered places to overwinter individually.
Overwintering is part of the annual cycle:
colony → production of new queens → mating → dispersal → overwintering → founding of a new nest.
Recent work on nest architecture also shows that the summer nest is a temporary, structurally complex construction that grows substantially over the season [7].
3. Diet and interactions with Apis mellifera
3.1. A generalist predator
Interpreting V. crabro as a honey bee specialist is unsupported by the literature.
Research on the hornet’s biology and behaviour in Sardinia found a broad, generalist diet [2]. Honey bees are available prey in some circumstances and account for only part of the hornet’s feeding niche.
For bait design, this shifts the question to which food cues hornets respond to at a given stage of the season.
3.2. Predation on foragers
Observations by Baracchi et al. in central Italy showed that V. crabro often intercepts returning foragers outside the hive [1].
A returning forager is a relatively large and readily recognisable prey item.
An apiary can therefore become a predictable food source, especially when the hornet colony’s demand for protein is high.
3.3. Honey bee defences
Honey bees can defend themselves collectively.
Colonies of A. mellifera can surround an attacking hornet. This behaviour, known as balling, can raise the temperature around the hornet beyond what it can tolerate [1].
Colony size can therefore influence the bees’ ability to withstand predation.
This has a practical implication for beekeepers:
a strong colony is the first line of defence against predation pressure.
4. Trophallaxis and the colony’s food economy
Feeding behaviour in social wasps creates a network for distributing food throughout the nest.
Larval saliva in V. crabro contains carbohydrates and amino acids and forms part of the colony’s food supply. Kojima’s comparative study found relatively high levels of specific amino acids and described a role for larval secretions in hornet social behaviour [3].
Food moves among individuals within the colony.
A worker can:
collect food;
process it;
carry it to the nest;
pass it to larvae or other adults;
receive food from other colony members in turn.
Trophallaxis thus forms a biological distribution network.
For research on social wasp control, this network is of interest because a foraging worker could, in principle, carry a substance back to the colony.
5. Baits: from attraction to changes in behaviour
5.1. Sugar-based and protein-based food matrices
The choice of food matrix should account for the target species’ nutritional needs.
Sugar-based baits may be more attractive when the colony is seeking carbohydrates.
Protein-based matrices may become more relevant when the brood’s demand for protein is high.
Research in Campania in 2025 compared beer, canned baits and commercial fish-based food. It found a marked preference in V. crabro for beer in September and October [8].
The result does not establish the best bait year-round. It shows that attractiveness depends strongly on the species, the season and local conditions.
5.2. Attracting hornets near hives
Baits can be counterproductive if their placement is poorly planned.
A baited trap deliberately creates a point of attraction. If it is right next to the hives, it can increase hornet activity in the area it is meant to protect.
Research has not shown that food-baited traps cause a lasting increase in the population of V. crabro. A trap should nevertheless be understood as a factor that changes where hornets gather, rather than as a passive barrier.
5.3. Monitoring and control serve different purposes
A bait that works well for monitoring may be unsuitable for control.
Monitoring aims to maximise the chance of detecting the species.
Control research, by contrast, aims to:
target the intended species;
avoid exposing other organisms;
maintain attraction for the necessary period;
allow foragers to carry material to the nest when testing a Trojan horse approach.
These objectives can conflict.
6. The Trojan horse approach: the biological principle
Trophic transfer works differently from conventional trapping.
In an ingestible lethal bait system:
attraction → ingestion → death of the exposed individual.
In a trophic transfer system:
attraction → feeding and collection → transport to the nest → social transfer → colony exposure.
The intended target extends beyond the individual hornet to
the colony’s social network.
This approach has mainly been tested against V. velutina, with results supporting the feasibility of the principle in that species [4].
7. Protein baits and biocides: evidence from experimental studies
7.1. Fipronil: the best-documented experimental example
Fipronil has been studied in the greatest detail.
Barandika et al. examined protein baits containing this active ingredient in V. velutina. The study combined laboratory tests on larvae with field tests in multiple apiaries [4]. The experiment examined how larvae were exposed to the active ingredient through food brought into the colony, in addition to any effects on adult foragers. Several concentrations were tested in the laboratory, and the formulation that performed best there was then used in the field trial [4].
At apiaries under high pressure from V. velutina, observers recorded a significant reduction in hornet activity for at least two weeks. The reduction was greater where more bait was consumed [4].
This provides a proof of principle for control through trophic transfer.
7.2. Fipronil metabolism in larvae
A subsequent analytical study examined what happens after ingestion.
Using HPLC-DAD and GC-MS, the researchers detected fipronil and its metabolites fipronil sulfone and fipronil sulfide in larvae [6]. This matters because the effects of a bait may depend on compounds formed after ingestion as well as on the parent compound. The target organism can convert the active ingredient into metabolites with different toxicological properties.
The authors noted that fipronil sulfone is highly toxic. This metabolic pathway could have implications for future research on lower-dose systems [6]. It remains a research question with no established field application for the European hornet.
8. Which biocides have researchers studied?
Recent studies have looked beyond fipronil.
8.1. Acetamiprid
A study published in December 2025 evaluated the oral toxicity of acetamiprid to workers of V. velutina nigrithorax [5]. Among the compounds tested, acetamiprid had the highest oral potency and acted relatively quickly under the study conditions.
Acetamiprid is a neonicotinoid that acts as an agonist at nicotinic acetylcholine receptors [5]. The experiment showed a marked effect on hornets after ingestion. The authors also emphasised the need to assess risks to pollinators and other non-target organisms [5].
8.2. Spinosad
Spinosad showed a different profile.
In the study by Souto et al., its effects developed progressively and included both mortality and behavioural changes [5]. Spinosad acts orally through a neurotoxic mechanism distinct from that of neonicotinoids. Its sublethal effects on foraging and the ability to return to the nest are also worth studying. In a trophic-transfer system, a compound that rapidly repels or immobilises a forager may prevent it from carrying bait back to the colony.
8.3. Cypermethrin
Cypermethrin caused substantial mortality after ingestion in the 2025 tests, but hornets also showed marked avoidance [5]. Even a highly toxic compound may be unsuitable for trophic transfer if the target species detects and avoids it.
Formulation research therefore has to answer two questions. How toxic is the compound? And can it remain effective while allowing the hornets to accept and transport the bait?
8.4. Natural pyrethrins
The natural pyrethrin mixture was less effective than acetamiprid, spinosad and cypermethrin under the study conditions [5]. Pyrethrins remain of interest for comparative research because they are neurotoxic and can degrade rapidly in the environment. For trophic transfer, selectivity and forager behaviour remain key uncertainties.
9. Qualitative comparison of the main compounds studied
The available evidence supports the following comparison:
Compound or class | Evidence in vespids | Relevance to trophic-transfer bait research | Main limitation |
Fipronil | Substantial, including a field trial in V. velutina [4] | High research interest | Limited selectivity, risks to non-target organisms and effects of metabolites [4,6] |
Acetamiprid | High oral toxicity in V. velutina [5] | High research interest, with transfer yet to be tested | Risks to pollinators and uncertainty about whether individual toxicity translates into colony-level effects |
Spinosad | High oral toxicity and behavioural effects [5] | Of research interest | Bait acceptance, transport and effects on non-target organisms still need assessment |
Cypermethrin | High oral toxicity [5] | Less suitable for transfer research | Observed avoidance or repellency [5] |
Natural pyrethrins | Activity documented, with lower potency in the test [5] | Of possible research interest | Lower efficacy and persistence; non-selective |
This table highlights a point often overlooked: the compound with the highest acute toxicity is not necessarily the most suitable for trophic transfer.
10. What would a true “Trojan” bait need?
A formulation for research on trophic transfer would ideally meet at least six requirements.
10.1. High attractiveness
The hornet must recognize the substrate as food.
10.2. Low repellency
The active ingredient must not deter feeding. Cypermethrin is an instructive example: hornets showed avoidance in the 2025 study [5].
10.3. Stability during collection
The bait must remain palatable long enough for hornets to collect and transport it.
10.4. Compatibility with social behaviour
Hornets must carry the material into the nest and transfer it to the brood.
10.5. An appropriate delay before onset
An excessively rapid effect could be counterproductive: a forager immobilized at the bait is unlikely to carry it to the nest.
10.6. Ecological selectivity
This is probably the hardest requirement to meet. An ideal formulation would be recognized mainly by the target species and pose minimal risk to bees, wild hymenopterans, flies and other organisms.
11. The future: from toxicity to behavioural selectivity
Future research could shift its focus from the compound to the behaviour of the target species.
11.1. Semiochemistry
V. crabro has complex chemical communication systems. Studies of mating behaviour have shown that males respond to chemical cues associated with females and have identified differences in cuticular lipid profiles [9]. These findings open up research into semiochemicals that could increase species-specific attraction. This approach could address a limitation of general-purpose food baits.
11.2. Pheromones and alarm signals
Researchers have also investigated compounds involved in the response to alarm signals in V. crabro [10]. A promising line of inquiry is to understand which compounds alter the insect's activity, orientation or tendency to remain near a resource. Their suitability as bait cues is a separate question.
11.3. Designing bait around behaviour
Future bait could be conceived as a system with several components:
semiochemical cue → attraction; food matrix → acceptance; active ingredient → biological effect; delayed onset → return to the nest; trophallaxis → distribution; low environmental persistence → reduced non-target exposure.
This approach would account for more steps in hornet behaviour than a conventional trap containing food and insecticide.
12. A crucial question: time to onset
Timing is particularly important in the Trojan-horse approach. If the active ingredient kills an individual almost immediately, the carrier may fail to reach the nest. If the effect takes too long, the amount transferred may be insufficient. Mortality is only one factor to consider.
The relevant combination is: acceptance × amount ingested × return time × amount transferred × brood exposure × colony mortality.
This is one of the main reasons why individual oral toxicity data, although important, are insufficient for developing a bait that works through trophic transfer. An LC₅₀ or LD₅₀ result alone cannot predict efficacy at the nest level.
13. The problem of sublethal doses
Another line of research concerns sublethal effects. A compound may leave a worker alive initially while affecting its:
orientation;
flight activity;
foraging ability;
return to the nest;
ability to feed the brood;
social interactions
In the 2025 study, for example, spinosad caused both mortality and behavioural changes, while hornets showed avoidance of cypermethrin [5]. These findings suggest that the highest acute lethality may not provide the best pharmacological profile for a Trojan bait. An active ingredient that could preserve the ability to transport bait while gradually impairing colony function might be of greater biological interest, although it would require much more extensive research.
14. Metabolism as a design tool
The case of fipronil and fipronil sulfone is particularly interesting for another reason. The target insect's metabolism could inform the design of a control system. The substance in the bait could act as a precursor to a more active metabolite produced by the insect itself.
Experiments on V. velutina show that fipronil is converted to fipronil sulfone and fipronil sulfide inside the larvae [6]. This observation suggests a line of pharmacological research:
an ideal formulation might contain a compound that the target organism itself metabolizes into a more active substance.
In theory, this could reduce the initial amount of active ingredient. However, the same metabolic transformation would also need to be studied in non-target organisms before it could be regarded as an ecotoxicological advantage.
15. Towards more selective compounds
Conventional classes of insecticides were generally developed to target broad groups of insects.
Controlling colonies of vespid wasps calls for much greater selectivity.
Future research could explore:
15.1. Compounds with selective neurophysiological effects
The aim would be to exploit pharmacological differences between the target and non-target pollinators.
15.2. Growth regulators
A compound that interferes with larval development or metamorphosis could be better suited to a colony-level approach than a very fast-acting pyrethroid. This hypothesis would require direct testing in vespid wasps. The known mode of action in other insects is insufficient to establish it.
15.3. Behavioural modulators
A compound that alters social behaviour or foraging could theoretically impair a colony's ability to sustain itself, even without immediately causing high mortality among individual insects.
15.4. Proinsecticide systems
The most novel concept is the one suggested by the transformation of fipronil: a relatively less active compound that the target organism converts into a more potent metabolite.
This approach is scientifically promising but calls for a much more sophisticated toxicological assessment.
16. Why Vespa crabro needs species-specific research
Nearly all modern evidence on the Trojan-horse approach comes from studies of V. velutina. This reflects the fact that V. velutina is an invasive alien species with a substantial impact on European beekeeping and biodiversity. V. crabro differs in its ecology. It is native to most of Europe and plays a role as a predator in ecosystems.
The Sardinian study also found that the species showed no substantial behavioural changes in the area surveyed that would suggest a strongly invasive pattern [2]. It would therefore be methodologically unsound to apply a protocol developed for V. velutina directly to V. crabro. Researchers would first need to determine the following for V. crabro:
seasonal food preferences;
rate of bait consumption;
amount carried to the nest;
frequency of trophallaxis;
susceptibility to oral exposure at different life stages;
avoidance behaviour;
metabolism of the active ingredient;
sublethal effects;
exposure of non-target organisms.
17. Proposed experimental framework
Future research on V. crabro should proceed in stages, with intermediate steps between laboratory studies and field trials.
Phase 1 — Assessing attractiveness
Compare sugar-based and protein-based matrices at different times in the season.
Phase 2 — Feeding behaviour
Measure the amount consumed and the time spent at the bait.
Phase 3 — Transport
Determine the percentage of foragers that return to the nest after feeding.
Phase 4 — Social transfer
Quantify the transfer of food to the brood and adults.
Phase 5 — Pharmacology
Compare the oral toxicity and sublethal effects of the compounds.
Phase 6 — Metabolism
Identify the metabolites and characterize their toxicological profiles.
Phase 7 — Selectivity
Compare with A. mellifera and the non-target insects most likely to be exposed.
Phase 8 — Controlled microcolonies
Assess effects on colony growth as well as individual mortality.
Phase 9 — Field trial
Proceed only after demonstrating an acceptable balance of benefits and risks.
This sequence would help avoid a major pitfall in applied research: confusing individual toxicity with effective colony management.
18. Biocides and regulation: the boundary between research and application
Regulatory requirements are particularly important for baits containing biocides. Regulation (EU) No 528/2012 sets out the European framework for approving active substances and authorising biocidal products. A biocidal product may be placed on the market or used only in accordance with the applicable authorisation requirements. Scientific studies of its active ingredient alone do not confer authorisation [11,12].
The distinction is essential: a compound studied in the laboratory ≠ an authorised product.
Likewise: a product authorised for a specific use ≠ general permission to prepare bait for a different target organism.
Fipronil illustrates the distinction. The ECHA database lists its active-substance approval status as “expired” for product type 18 (PT18), while individual biocidal products are authorised in various countries for specific uses [12]. The status therefore needs to be checked for the active substance, the product, the product type and the relevant national or Union authorisation. For V. crabro, the available scientific evidence is also insufficient to regard biocidal baits based on trophic transfer as a standard control method.
19. Why biocidal baits can make the problem worse
An often underestimated risk is that a single bait can simultaneously serve as: a means of control; an attractant; a source of environmental exposure.
An attractive bait draws more predators to the point where it is placed. At an apiary, this can have the opposite of the intended effect. Protein bait can also attract other organisms, and a broad-spectrum insecticide can affect species outside the scope of control. The issue is particularly important in a Trojan-horse system because the active ingredient enters the colony's social network. Biological efficiency and ecological risk can therefore increase together.
That is why selectivity should be the main criterion in future development.
20. An integrated approach to protecting honey bee colonies
In practical beekeeping, an integrated approach remains the most appropriate strategy.
Strengthening colonies
A strong colony is better able to defend itself [1].
Managing the hive entrance
Carefully restricting access can help more vulnerable colonies. Most of the evidence comes from management of V. velutina, but restricting access is consistent with the defensive behaviour of honey bees.
Monitoring
Baits can help track seasonal activity and determine whether the predator is present [8].
Locating the nest
When predation pressure persists, finding the source is often more appropriate than indiscriminately increasing the number of traps.
Professional control
A problematic nest should be dealt with using procedures and products permitted under the applicable regulations.
Experimental research
The Trojan-horse approach is a subject of scientific research and remains distinct from standard control practice.
21. Looking ahead: from poisoned bait to applied behavioural ecology
Early studies focused on one question: which substance kills hornets most effectively?
The next generation of studies should address a more complex question: which combination of behaviour, bait and pharmacology can disrupt a colony with the least impact on the ecosystem?
An advanced strategy would need to account for the whole sequence: phenology → attraction → ingestion → transport → trophallaxis → metabolism → sublethal or lethal effects → colony collapse.
It would also need to account for: selectivity for the target → minimising effects on non-target organisms → limiting environmental dispersal → checking regulatory requirements.
In this model, the active ingredient is one component of the system.
Control depends on how the compound interacts with the hornet's social biology.
22. Conclusions
The biology of Vespa crabro reveals a complex system in which predation, food transfer and reproduction are closely linked. Its interaction with Apis mellifera is generally opportunistic. Field observations indicate that predation occurs mainly outside the hive, especially on foragers, while strong colonies mount an effective collective defence [1,2].
The latter part of the season is of particular interest to beekeepers because the hornet colony reaches peak activity and its food requirements rise [2]. Conventional baits are useful for monitoring, but the results must be interpreted in light of their attraction effect. A trap can temporarily remove captured individuals without necessarily reducing overall predation pressure. Under some conditions, it can even create a new local concentration of predators.
The Trojan-horse concept is of particular biological interest because it exploits the social structure of the hornet colony. The strongest experimental evidence comes from studies of V. velutina using protein baits containing fipronil [4]. Subsequent studies of metabolism also demonstrated the formation of fipronil sulfone and fipronil sulfide in larvae, suggesting a line of research into systems that exploit metabolic bioactivation of the active ingredient [6].
More recent work has extended the scope to acetamiprid, spinosad, cypermethrin and natural pyrethrins. Acetamiprid and spinosad showed particularly notable oral toxicity profiles in V. velutina, while cypermethrin showed an important behavioural limitation: repellency [5].
These findings point to a fundamental principle:
the suitability of a compound for Trojan bait depends on acceptance, transport, social transfer, efficacy at colony level and minimal exposure of non-target organisms as well as toxicity.
For V. crabro, much of the research remains to be done. Studies should now focus directly on the European hornet and examine the following together:
seasonal food preferences;
sugar- and protein-based attractants;
semiochemistry;
transport behaviour;
trophallaxis;
oral toxicity;
sublethal effects;
metabolism;
selectivity with respect to A. mellifera;
exposure of non-target insects;
colony-level effects.
The most promising direction is therefore to design a system that combines behavioural and pharmacological approaches to colony control with enough selectivity to be integrated into modern apiary management.
In this context, the Trojan-horse approach is a potential tool of applied behavioural ecology. It remains experimental for V. crabro and uses the predator's social organisation to distribute the active substance.
Notes and scientific references
[1] Baracchi, D., Cusseau, G., Pradella, D., & Turillazzi, S. (2010). Defence reactions of Apis mellifera ligustica against attacks from the European hornet Vespa crabro. Ethology Ecology & Evolution, 22, 281–294. DOI: 10.1080/03949370.2010.502323. The study documents predation by V. crabro on honey bee foragers and the bees' collective defence response. (PubMed Central (PMC))
[2] Pusceddu, M., Lezzeri, M., Cocco, A., Floris, I., & Satta, A. (2022). Bio-Ethology of Vespa crabro in Sardinia (Italy), an Area of New Introduction. Biology, 11, 518. DOI: 10.3390/biology11040518. A study of the phenology, foraging and social behaviour of V. crabro and its predation on A. mellifera. (MDPI)
[3] Kojima, J. (1991). Comparative study of the composition of hornet larval saliva, its effect on behaviour and role of trophallaxis. Comparative Biochemistry and Physiology Part C, 99, 79–84. DOI: 10.1016/0742-8413(91)90079-9. The study includes V. crabro and documents the composition of larval saliva and the role of food exchange in the colony. (ScienceDirect)
[4] Barandika, J. F. et al. (2023). Efficacy of Protein Baits with Fipronil to Control Vespa velutina nigrithorax in Apiaries. Animals, 13, 2075. DOI: 10.3390/ani13132075. A laboratory and field study on the trophic transfer of fipronil via protein bait. The field trial involved 222 beekeepers, of whom 90 returned the questionnaire. The effect was most evident in apiaries under high pressure from V. velutina. (PubMed)
[5] Malaquias Souto, P. et al. (2025). Assessing the oral toxicity of acetamiprid, spinosad, cypermethrin, and pyrethrins in the invasive hornet Vespa velutina nigrithorax. Scientific Reports, 15, 45112. DOI: 10.1038/s41598-025-31988-x. A comparative oral toxicity study of four formulations containing acetamiprid, spinosad, cypermethrin and a mixture of natural pyrethrins. Acetamiprid showed the greatest oral potency in the experimental system. Spinosad caused mortality and sublethal changes, and hornets showed avoidance of cypermethrin. (Nature)
[6] de la Hera, O., Izaguirre, A., Rivas, A., & Alonso, R. M. (2024). QuEChERS-Based Method for the Determination of Fipronil in Protein Baits and Vespa velutina Larvae by HPLC-DAD and GC-MS. Separations, 11, 317. The study experimentally documents fipronil and its metabolites, fipronil sulfone and fipronil sulfide, in V. velutina larvae, with implications for research on formulations and metabolic bioactivation. (MDPI)
[7] Jurczyková, T. et al. (2026). Chemical and structural analysis of a European hornet nest. Scientific Reports, 16, 9395. A multidisciplinary study of the structure and composition of a V. crabro nest, which helps explain the temporary nature and architecture of the colony's nest. (Nature)
[8] Martano, M., Power, K., Montagnaro, S., Esposito, M., D'Emilio, C., & Maiolino, P. (2026). Evaluation of Bait Attractiveness for Vespa orientalis and Vespa crabro (Hymenoptera: Vespidae) in Urban and Apiary Environment of Campania Region (Italy). Insects, 17(4), 368. DOI: 10.3390/insects17040368. The study covered 15 apiaries and 10 urban areas in September and October 2025. V. crabro showed a marked preference for beer-based bait over the other matrices tested. (MDPI)
[9] Spiewok, S., Schmolz, E., & Ruther, J. (2006). Mating system of the European hornet Vespa crabro: male seeking strategies and evidence for the involvement of a sex pheromone. Journal of Chemical Ecology, 32, 2777–2788. DOI: 10.1007/s10886-006-9162-4. The study provides experimental evidence of chemical cues involved in sexual attraction in V. crabro, with potential implications for applied semiochemistry. (PubMed)
[10] MacLean, C., & Schmolz, E. (2004). Calorimetric investigations on the action of alarm pheromones in the hornet Vespa crabro. Thermochimica Acta, 414, 71–77. A study of physiological and behavioural responses to chemical cues associated with the species' alarm system.
[11] European Commission. Regulation on the supply and use of biocidal products. Regulation (EU) No 528/2012 governs the approval of active substances and the authorisation of biocidal products. The Commission specifies that placing a biocidal product on the market or using it requires compliance with the applicable authorisation framework. (Public Health)
[12] ECHA – European Chemicals Agency. Information on biocides / Biocidal active substances. The ECHA database lists the active-substance approval for fipronil in PT18 as “Expired”, while individual products may hold authorisations in specific markets and under specific conditions of use. (ECHA)
Methodological note. The evidence on fipronil, acetamiprid, spinosad, cypermethrin and pyrethrins cited in the biocide sections comes primarily from research on V. velutina. The article presents it as a review of current research and possible directions for experiments. The evidence does not establish efficacy or authorise or prescribe use against V. crabro. The quantitative findings from experimental studies should be read in their research context.
Author: Davide Simeone
Published: 16 August 2026
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