Control of Hyalomma lusitanicum (Acari: Ixodidade) Ticks Infesting Oryctolagus cuniculus (Lagomorpha: Leporidae) Using the Entomopathogenic Fungus Beauveria bassiana (Hyocreales: Clavicipitaceae) in Field Conditions

Emerging Hyalomma lusitanicum: From identification to vectorial role and integrated control

In the Mediterranean basin, the tick species Hyalomma lusitanicum Koch stands out among other species of the Hyalomma genus due to its wide distribution, and there is great concern about its potential role as a vector and/or reservoir and its continuous expansion to new areas because of climate warming and human and other animal movements. This review aims to consolidate all the information on H. lusitanicum, including taxonomy and evolution, morphological and molecular identification, life cycle, sampling methods, rearing under laboratory conditions, ecology, hosts, geographical distribution, seasonality, vector role and control methods. The availability of adequate data is extremely relevant to the development of appropriate control strategies in areas where this tick is currently distributed as well as in new areas where it could become established in the near future.

A comparison between the effectiveness of the fungi Beauveria bassiana and Metarhizium anisopliae for the control of Argas persicus with the emphasis of histopathological changes in the integument

Argas persicus is an important ectoparasite of domestic fowl that causes heavy economic losses to the poultry industry. The present study was carried out to compare and assess the effects induced by spraying the fungi Beauveria bassiana and Metarhizium anisopliae separately, on the mobility and viability of semifed adult A. persicus, also to follow the histopathological effect induced by a selected concentration of 10¹⁰ conidia/ml of B. bassiana on the integument. Biological studies revealed a more or less similar pattern of response in adults treated with either of the two fungi (Increasing concentration resulting in more death along with examined period). As the estimated LC50 and LC95 of B. bassiana were recorded 5 × 10⁹ and 4.6 × 10¹² conidia/ml, respectively, and for M. anisopliae were 3 × 10¹¹ and 2.7 × 10¹⁶ conidia/ml respectively, the fungus B. bassiana was more efficient than M. anisopliae when applied at the same concentrations. The study revealed that spraying of Beauveria at 10¹² conidia/ml is sufficient to control A. persicus as it recorded 100% efficacy, so it might be selected to be the effective dose. Histological investigation of the integument treated with B. bassiana revealed the dispersal of the hyphal network on the after 11 days of treatment, accompanied by other changes. Results from our study verify the susceptibility of A. persicus to the pathogenic effect induced by spraying B. bassiana, which is sufficient for its control with the recording better results.

The control of Hyalomma ticks, vectors of the Crimean–Congo hemorrhagic fever virus: Where are we now and where are we going?

At a time of major global, societal, and environmental changes, the shifting distribution of pathogen vectors represents a real danger in certain regions of the world as generating opportunities for emergency. For example, the recent arrival of the Hyalomma marginatum ticks in southern France and the concurrent appearance of cases of Crimean–Congo hemorrhagic fever (CCHF)—a disease vectored by this tick species—in neighboring Spain raises many concerns about the associated risks for the European continent. This context has created an urgent need for effective methods for control, surveillance, and risk assessment for ticks and tick-borne diseases with a particular concern regarding Hyalomma sp. Here, we then review the current body of knowledge on different methods of tick control—including chemical, biological, genetical, immunological, and ecological methods—and the latest developments in the field, with a focus on those that have been tested against ticks from the genus Hyalomma. In the absence of a fully and unique efficient approach, we demonstrated that integrated pest management combining several approaches adapted to the local context and species is currently the best strategy for tick control together with a rational use of acaricide. Continued efforts are needed to develop and implement new and innovative methods of tick control.

Disease-bearing Hyalomma ticks are an increasingly emerging threat to humans and livestock worldwide. Various chemical, biological, genetic, and ecological methods for tick control have been developed, with variable efficiencies. Today, the best tick control strategy involves an integrated pest management approach.

A Review of Commercial Metarhizium- and Beauveria-Based Biopesticides for the Biological Control of Ticks in the USA

There is a need for the development of sustainable, nonchemical tick management strategies. Mycoacaricide and mycoinsecticide product development worldwide has focused primarily on fungi in the genera Beauveria (Hypocreales: Cordycipitaceae) and Metarhizium (Hypocreales: Clavicipitaceae). Microbial biopesticides containing entomopathogenic fungi have potential in tick management. However, despite considerable progress in the development of fungal biopesticides over the past 20 years, the establishment of commercial products available for use against ticks continues to be slow. We reviewed published scientific literature and compiled a comprehensive list of reports of the effectiveness of commercial biopesticides based on the fungal genera Metarhizium and Beauveria and registered for use in the USA against ixodid ticks under laboratory and field conditions. We also report on results when these biopesticides were used as a part of integrated tick management. Until efficacious fungus-based products become more available, tick management will rely primarily on synthetic chemical acaricides, with natural-product acaricides as the alternative.

Molecular identification of zoonotic Rickettsia species in Ixodidae parasitizing wild lagomorphs from Mediterranean ecosystems

A survey study was carried out to identify tick species parasitizing wild lagomorphs in Mediterranean ecosystems in southern Spain and to determine the occurrence of Rickettsia species present in these ticks in this region. A total of 1304 European wild rabbits (Oryctolagus cuniculus) and 58 Iberian hares (Lepus granatensis) were individually examined for the presence of ticks. Ticks were found in 42.9% and 50% of the wild rabbits and hares sampled, respectively. A total of 1122 ticks were collected and five species, including Rhipicephalus pusillus, Hyalomma lusitanicum, Haemaphysalis hispanica, Ixodes ventalloi and Rhipicephalus sanguineus sensu lato (s.l.), were microscopically and molecularly identified at the 16S rRNA gene. This is the first study on Ixodidae parasitizing Iberian hares. The presence of Rickettsia DNA was assessed in 254 tick pools (according to hunting states, lagomorph species, tick species and tick development stage) using PCR assays targeting the rOmpA, rOmpB and gltA. Twenty-seven pools (10.6%) were positive to Rickettsia DNA. Five zoonotic Rickettsia species were identified, being Rickettsia massiliae the most frequent (4.7%), followed by Rickettsia sibirica subsp. mongolitimonae (2.8%), Rickettsia slovaca (2.0%), Rickettsia aeschlimannii (0.8%) and Rickettsia africae (0.4%). The results suggest that wild rabbits and Iberian hares are parasitized by a wide range of tick species and that these lagomorphs may play an important role in the sylvatic cycle of some zoonotic Rickettsia species in Mediterranean ecosystems. Our data represent the first report of R. massiliae, R. aeschlimannii, R. slovaca and R africae in ticks collected in wild lagomorphs in Europe, and the first report of not imported R. africae in this continent. Since R. slovaca and R. africae DNA was detected in tick species different to their main vectors, further studies are warranted to unravel the role of wild lagomorphs in the epidemiology of these vector-borne pathogens.

Entomopathogenic Fungi and Bacteria in a Veterinary Perspective

Simple Summary

Several fungal species are well suited to control arthropods, being able to cause epizootic infection among them and most of them infect their host by direct penetration through the arthropod’s tegument. Most of organisms are related to the biological control of crop pests, but, more recently, have been applied to combat some livestock ectoparasites. Among the entomopathogenic bacteria, Bacillus thuringiensis, innocuous for humans, animals, and plants and isolated from different environments, showed the most relevant activity against arthropods. Its entomopathogenic property is related to the production of highly biodegradable proteins. Entomopathogenic fungi and bacteria are usually employed against agricultural pests, and some studies have focused on their use to control animal arthropods. However, risks of infections in animals and humans are possible; thus, further studies about their activity are necessary.

Abstract

The present study aimed to review the papers dealing with the biological activity of fungi and bacteria against some mites and ticks of veterinary interest. In particular, the attention was turned to the research regarding acarid species, Dermanyssus gallinae and Psoroptes sp., which are the cause of severe threat in farm animals and, regarding ticks, also pets. Their impact on animal and human health has been stressed, examining the weaknesses and strengths of conventional treatments. Bacillus thuringiensis, Beauveria bassiana and Metarhizium anisopliae are the most widely employed agents. Their activities have been reviewed, considering the feasibility of an in-field application and the effectiveness of the administration alone or combined with conventional and alternative drugs is reported.

Sensitivity of Ixodes ricinus (L., 1758) and Dermacentor reticulatus (Fabr., 1794) ticks to entomopathogenic fungi isolates: preliminary study

Entomopathogenic fungi of the genus Beauveria and Metarhizium play an important role in controlling the population of arthropods. However, the data on their effectiveness against ticks focus mainly on species that do not occur in Europe. The aim of the study was to assess the effectiveness of entomopathogenic fungi against two of the most important tick species in Europe: Ixodes ricinus and Dermacentor reticulatus. In our study, the majority of tested entomopathogenic fungi strains showed potential efficacy against both tick species; however, D. reticulatus was less susceptible in comparison to I. ricinus. The observed mortality of ticks was up to 100% by using all commercial strains as well as three out of nine of the environmental strains. Among all tested fungi, the most effective against both tick species was environmental strain Metarhizium anisopliae LO4(1) with LC₅₀ values: 2.6 × 10³ cfu/ml–5.7 × 10⁵ cfu/ml. Botanigard proved to be more effective than MET52 with LC₅₀ values: 6.8 × 10³ cfu/ml–3.3 × 10⁶ cfu/ml. The conducted bioassays indicate the potential possibility of using the environmental isolates of entomopathogenic fungi, as well as commercial strains in control of local populations of I. ricinus and D. reticulatus; however, the possibility of using them in vivo requires more research.

Comparative Ecology of Hyalomma lusitanicum and Hyalomma marginatum Koch, 1844 (Acarina: Ixodidae)

The genus Hyalomma belongs to the Ixodidae family and includes many tick species. Most species in this genus are African species, but two of them, Hyalomma lusitanicum and Hyalomma marginatum, are also found in Europe and, owing to their morphological similarity, it is very difficult to tell them apart. This is a major concern because their phenology and vector capacities are quite different. Moreover, they share many habitats and both are currently spreading to new areas, probably due to climate change and animal/human movements. In this study, we review the described ecology of the two species and provide further interesting data on H. lusitanicum based on the authors' experience, which could be useful in assessing the risk they pose to humans and animals.

Sensitivity of Entomopathogenic Fungi and Bacteria to Plants Secondary Metabolites, for an Alternative Control of Rhipicephalus (Boophilus) microplus in Cattle

Boophilus (Rhipicephalus) microplus is a one host hard tick widespread in warm climates worldwide, responsible for great economic losses. To avoid resistance in ticks population, induced by the repeated administration of conventional acaricides and/or the presence of residues in the environment in meat and in milk, an alternative approach can be achieved using entomopathogenic microorganisms such as fungi and bacteria, or essential oils (EOs). The aim of the present study was to evaluate the in vitro sensitivity of Beauveria bassiana, Metarhizium anisopliae, Scopulariopsis sp, Bacillus thuringiensis and Proteus mirabilis to Eucalyptus globulus, Lavandula hybrida, Pelargonium graveolens EOs and to their main constituents such as lynalool, linalyl-acetate, geraniol, citronellol and 1,8 cineole. EOs has been chemically characterized by GC-MS. Fungal isolates were tested by a microdilution assay to achieve minimal inhibitory concentration (MIC) of both EOs and main components. The sensitivity of bacteria was evaluated by an agar disk diffusion. The results obtained show the feasibility of an integrate approach for an eco-friendly control of R. microplus by use of both entomopathogenic fungi and P. graveolens EO. L. hybrida could be an interesting alternative when B. bassiana is not employed. Conversely, a combined use of B. thuringiensis and EOs would not be advisable in the integrate control of ticks.