Comparative response of Metarhizium brunneum to the cuticles of susceptible and resistant hosts.

Earlier studies demonstrated that Metarhizium brunneum, usually a broad-host pathogen of arthropods, is unable to complete its pathogenic life cycle when inoculated on the fungus-resistant tick, Hyalomma excavatum engorged females. While the fungus penetrates the cuticle of fungus-susceptible tick, Rhipicephalus annulatus females, it is unable to penetrate the cuticle of fungus-resistant tick, and even perishes on its surface. This is probably due to high concentration of antifungal fatty acids and probably also due to a hypersensitive-like response of the tick.

Efficacy of the entomopathogenic fungus Metarhizium brunneum in controlling the tick Rhipicephalus annulatus under field conditions.

High infectivity of entomopathogenic fungi to ticks under laboratory conditions has been demonstrated in many studies. However, the few reports on their use under field conditions demonstrate large variations in their success, often with no clear explanation. The present study evaluated the factors affecting the efficacy of the fungus Metarhizium brunneum against the tick Rhipicephalus (Boophilus) annulatus.

Temporal association of ambient temperature and relative humidity with Spirocerca lupi infection of Onthophagus sellatus: a 14-year longitudinal study.

The parasitic nematode Spirocerca lupi causes major morbidity and mortality in dogs. The scarab beetle Onthophagus sellatus is its major intermediate host in Israel. We investigated the prevalence of beetle infection by S.

On-host control of the brown dog tick Rhipicephalus sanguineus Latreille (Acari: Ixodidae) by Metarhizium brunneum (Hypocreales: Clavicipitaceae).

Ticks are obligatory blood-sucking arthropods. Their life cycle includes a relatively short period of feeding on a vertebrate host and a long off-host period spent in the upper layer of the soil. Entomopathogenic fungi are known to be highly effective tick pathogens and the on-host application of these fungi may be a promising economic approach for tick control.

Resistant ticks inhibit Metarhizium infection prior to haemocoel invasion by reducing fungal viability on the cuticle surface.

We studied disease progression of, and host responses to, four species in the Metarhizium anisopliae complex expressing green fluorescent protein (GFP). We compared development and determined their relative levels of virulence against two susceptible arthropods, the cattle tick Rhipicephalus annulatus and the lepidopteran Galleria mellonella, and two resistant ticks, Hyalomma excavatum and Rhipicephalus sanguineus. Metarhizium brunneum Ma7 caused the greatest mortality of R.

Control of tick populations by spraying Metarhizium anisopliae conidia on cattle under field conditions.

Conidia of the entomopathogenic fungus, Metarhizium anisopliae, in oil/water formulation (1 × 10(8) conidia/ml) were sprayed at 3 weekly intervals on Rhipicephalus evertsi evertsi and Rhipicephalus (Boophilus) decoloratus ticks while feeding on Afrikana bulls grazing in paddocks for a period of 1 year. The fungus reduced the on-host tick populations by 83% 3 month after commencement of the experiment. The formulation by itself had only minimal effect on the tick population.

Characterization of Onthophagus sellatus as the major intermediate host of the dog esophageal worm Spirocerca lupi in Israel.

Spirocerca lupi is a parasitic nematode of dogs, that causes significant morbidity and mortality. Its intermediate hosts in Israel have never been described. The aim of this study was therefore to identify the intermediate hosts of S.

The effect of temperature and relative humidity on the formation of Metarhizium anisopliae chlamydospores in tick eggs.

The influence of ambient conditions on the development of Metarhizium anisopliae chlamydospores in tick eggs is reported for the first time. The infection of tick eggs by M. anisopliae involves common events, such as adhesion, conidial germination, appressoria formation, invasion, and development within the eggs.

Novel technique for quantifying adhesion of Metarhizium anisopliae conidia to the tick cuticle.

The present study describes an accurate quantitative method for quantifying the adherence of conidia to the arthropod cuticle and the dynamics of conidial germination on the host. The method was developed using conidia of Metarhizium anisopliae var. anisopliae (Metschn.

Metarhizium anisopliae conidial responses to lipids from tick cuticle and tick mammalian host surface.

Conidial germination and the formation of appressoria are important events in the interactions between entomopathogenic fungi and their arthropod hosts. In this study, we demonstrate the effects of lipids extracted from tick epicuticle and the surface of a mammalian host (calf) on conidial germination and the development of appressoria in two subspecies of Metarhizium anisopliae, M. anisopliae var.

Pathogenicity of Metarhizium anisopliae (Hypocreales: Clavicipitaceae) to tick eggs and the effect of egg cuticular lipids on conidia development.

The ovicidal efficacy of two entomopathogenic hyphomycetes fungi--Metarhizium anisopliae variety acridum (M. an. ac.

Experimental transmission of field Anaplasma marginale and the A. centrale vaccine strain by Hyalomma excavatum, Rhipicephalus sanguineus and Rhipicephalus (Boophilus) annulatus ticks.

The cattle rickettsia Anaplasma marginale is distributed worldwide and is transmitted by about 20 tick species, but only Rhipicephalus simus, a strictly African tick species, has been shown to transmit the vaccine strain of A. centrale. The aim of the present study was to examine transmission of field strains of A.

Protection of Metarhizium anisopliae conidia from ultra-violet radiation and their pathogenicity to Rhipicephalus evertsi evertsi ticks.

Metarhizium anisopliae conidia were formulated in water or in olive oil containing 3% commercial sunscreens (Everysun or E45 Sun Block 50) and exposed to an artificial UV source for up to 5 hours. Survival of conidia after 5 h of exposure to UV in oil formulation was 29% when protected with Everysun, 40% when protected with E45, and 4% in control. In comparison, survival of conidia formulated in water was 13% when protected with Everysun, 24% when protected with E45, and 0% in control.

Life cycle of Hepatozoon canis (Apicomplexa: Adeleorina: Hepatozoidae) in the tick Rhipicephalus sanguineus and domestic dog (Canis familiaris).

The life cycle of the apicomplexan protozoon Hepatozoon canis in its natural hosts Rhipicephalus sanguineus (tick) and Canis familiaris (domestic dog) was studied in an experimental infection. Tick nymphs were fed on a naturally infected dog, or they were infected by percutaneous injection of blood. Dogs were inoculated by ingestion of adult ticks containing mature oocysts.

Biological control of ticks.

Ticks have numerous natural enemies, but only a few species have been evaluated as tick biocontrol agents (BCAs). Some laboratory results suggest that several bacteria are pathogenic to ticks, but their mode of action and their potential value as biocontrol agents remain to be determined. The most promising entomopathogenic fungi appear to be Metarhizium anisopliae and Beauveria bassiana, strains of which are already commercially available for the control of some pests.

Immunity against Boophilus annulatus induced by the Bm86 (Tick-GARD) vaccine.

Friesian cattle were immunized with two inoculations of anti-tick Bm86 (Tick-GARD) vaccine and were challenged 30 or 90 d later with Boophilus annulatus larvae derived from 1.2 g of eggs. No nymphs or adult ticks were found on the immunized cattle during four weeks after challenge.

The susceptibility of different species and stages of ticks to entomopathogenic fungi.

Boophilus annulatus, Hyalomma excavatum and Rhipicephalus sanguineus ticks were shown to be susceptible to different entomopathogenic fungi under laboratory conditions. Comparative results of bioassays using five different fungal species showed that some strains of Metarhizium anisopliae are highly pathogenic against various tick stages tested. In contrast to to their activity against insects, fungi also affected tick eggs.

Pathogenicity of entomopathogenic fungi to different developmental stages of Rhipicephalus sanguineus (Acari: Ixodidae).

The pathogenicity of 4 species of entomopathogenic fungi (Hyphomycetes species: Beauveria bassiana, Metarhizium anisopliae, Metarhizium flavoviride, and Paecilomyces fumosoroseus) to various developmental stages of Rhipicephalus sanguineus (Acari: Ixodidae) ticks was compared under laboratory conditions. The most virulent isolate, M. anisopliae-108, caused 92-96% mortality to unfed larvae and nymphs on day 7 postinfection (PI) and 100% mortality to unfed adults and engorged females on day 21 PI.

Entomopathogenic nematodes for the biocontrol of ticks.

Entomopathogenic steinemematid and heterorhabditid nematodes are increasingly used to control insect pests of economically important crops. Laboratory and field simulation trials show that ticks are also susceptible to these nematodes. The authors review the potential of entomogenous nematodes for the control of ticks.

Factors affecting the virulence of entomopathogenic nematodes to engorged female Boophilus annulatus ticks.

The laboratory trials rank the virulence of entomopathogenic nematode strains (3 heterorhabditids and 6 steinernematids) to engorged female Boophilus annulatus ticks according to 3 parameters of the infection process: the effect of exposure time on tick mortality, the quantity of nematodes that penetrate ticks, and the rate of tick mortality after the injection of 1, 2, or 3 nematodes. Exposure of the ticks to heterorhabditid strains for 6 hr resulted in >80% mortality, but only 20 or 65% mortality after exposure to most steinernematids. The quantity of nematodes recovered per tick exposed to nematodes for 6 days averaged from 16 to 141.

Transmission of hepatozoon canis to dogs by naturally-fed or percutaneously-injected Rhipicephalus sanguineus ticks.

Hepatozoon canis is an apicomplexan protozoan parasite of dogs, prevalent in Asia, Africa, and southern Europe. Experimental transmission of H. canis to dogs was performed with laboratory-reared Rhipicephalus sanguineus nymphs that fed on a naturally infected dog or were percutaneously injected with canine blood containing H.

Arthropods as predators of ticks (Ixodoidea).

The existing information on arthropods as predators of ticks is based mainly on sporadic observations and their role in reducing tick populations and in most cases is still not clear. Some reports suggest that in certain ecological habitats arthropods play an important role in the control of the tick population. This publication reports on some 100 relevant publications that appeared between 1906 and 1999.

Biocontrol of ticks by entomopathogenic nematodes. Research update.

Entomopathogenic nematodes (EPNs) are lethal to ticks even though they do not use their normal propagation cycle within tick cadavers. The tick Boophilus annulatus was found to be far more susceptible to EPNs than Hyalomma excavatum, Rhipicephalus bursa, or Rhipicephalus sanguineus. Ticks seem to be less susceptible to nematodes when feeding on a host.

Laboratory evaluation of pathogenicity of entomogenous nematodes to African tick species.

Five strains of entomogenous nematodes, Steinernema carpocapsae strains DD, Mexican, SR, and Heterorhabditis bacteriophora strains 1S5 and HP88, were tested for their pathogenicity to various developmental stages of five African tick species namely; Rhipicephalus appendiculatus, R. evertsi, Amblyomma variegatum, A. gemma, and Boophilus decoloratus.