Histopathological effects of the fruit extract of Citrullus colocynthis on the ovary of the tick Hyalomma dromedarii.

Hyalomma dromedarii is the predominant tick species parasitizing camels in Egypt which leads to mortalities in young animals that result in economic losses. It can transmit a lot of pathogens to animals and humans, such as the Crimean-Congo hemorrhagic fever virus, the Dhori virus, Kadam virus, Theileria annulata and spotted fever rickettsia. The continuous use of chemical acaricides has negative impact on the environment and almost led to acaricidal resistance, and hence the plant extracts represent alternative methods for controlling ticks. The present study was carried out to assess the histopathological effects on the ovary of fed female Hyalomma dromedarii following immersion in the ethanolic extract of fruits of Citrullus colocynthis (100 mg/mL). Light, scanning and transmission electron microscopy observations provided evidence that Citrullus colocynthis caused extensive damage to oocytes. Destruction of the internal organelles of oocytes, along with delay and/or inhibition of vitellogenesis were demonstrated. This is the first histological study that points to damage in H. dromedarii ovaries following treatment with the ethanolic extract of fruits of C. colocynthis. The data presented suggest that the plant extract affects the ovary either directly by entering the oocytes and/or indirectly by damaging the gut cells and digestion of blood that interfere with the development of oocytes, so it can be used as a promising agent for tick control.

Controlling Argas arboreus and A. persicus (Acari: Argasidae) by Adiantum capillus-veneris L. extracts with phytochemical analysis.

Argas species are parasites associated mostly with birds. Their infestations of the host may cause blood loss, resulting in anemia and finally death. Egypt loses millions of tons annually from birds because of these parasites. In addition, they can transmit pathogens to animals and humans. The acaricidal effects of the ethanolic and methanolic extracts of Adiantum capillus-veneris at different concentrations (1-4%) against semi-fed adults of Argas arboreus and A. persicus were investigated during 30 days after treatments. Mobility and mortality, acaricide efficacy, and the concentration that kills 50% of specimens (LC50) were estimated. The percentage of dead adults of both Argas species appeared during 6 days considerably until 30 days was significantly increased after treatment of either ethanol or methanol extracts of Adiantum at 1-4%, versus control groups. Ethanolic extracts (100% mortality) were more effective than methanolic ones (90% mortality) for both Argas species. Argas arboreus (80% efficacy and 5.9% LC50) was more resistant than A. persicus (100% efficacy and 4.1% LC50). Generally, males were more resistant than females. The chemical profile (by gas chromatography-mass spectrometry analysis) for the ethanolic extract of Ad. capillus-veneris at 4% (the most effective extract) was provided for the first time, which showed that the major group was sugars and sugar alcohols, and the main components were thymol-ß-d-glucopyranoside, D-(-)-Tagatofuranose, D-Arabinose, D-Galactose, D-(-)-Fructofuranose and Anthracene, 1-methyl. The efficiency of all these components was discussed. Based on the findings, bioactive compounds present in Ad. capillus-veneris have the potential to be applied as substitutes for synthetic acaricides and a biological control agent in the management of A. arboreus and A. persicus ticks.

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.

Effect of the entomopathogenic fungus Beauveria bassiana (Balsamo) on eggs and eclosing larvae of the tick Argas (Persicargas) persicus (Oken).

The present study was carried out to investigate the pathogenicity of the fungus Beauveria bassiana when diluted in triton X100 at concentrations of 106, 107, 108, 109, and 1010 conidia/ml and sprayed on the eggs of the tick Argas persicus. For each concentration, three replicates were made (each included about 10-16 eggs). Scanning electron microscopy was used to examine the surface morphology of the eggs and their eclosing larvae after treatment with a selected concentration of 107 conidia/ml B. bassiana. Biological studies revealed that all treated eggs demonstrated a delay in the hatching period (a highly significant increase) and a marked decrease in the hatching percentage, which increased as fungal concentrations increased, reaching 30 days (p < 0.001) and 2.9%, respectively, using 108 conidia/ml. Total inhibition of both parameters was observed at higher concentrations (109 and 1010 conidia/ml). Scanning electron microscopy of the eggs after using a concentration of 107 conidia/ml, revealed signs of fungal adhesion 2 days after treatment, whereas germination occurred after 7 days. Excessive conidiogenesis and sporulation on the egg surface were observed after 15 days of treatment. All eclosing larvae appeared paralyzed 1-4 days after hatching with many conidia covering their whole bodies. The findings suggest that the fungus affected tick larvae are either directly infected in the eggs or indirectly during eclosion.

Ultrastructural changes induced by the entomopathogenic fungus Beauveria bassiana in the ovary of the tick Argas (Persicargas) persicus (Oken).

The present study was carried out to assess the effects on the ovary of fed female Argas persicus following spraying of the ticks with spores of the fungus Beauveria bassiana suspended in triton X100 at a concentration of 107 conidia/mL. Scanning and transmission electron microscopy observations provided evidence that B. bassiana invaded the ovary, causing extensive morphological damage and deterioration of the developing oocytes. Destruction of the shape and internal organelles of young and previtellogenic oocytes and complete inhibition of vitellogenesis was evident. This histopathological study is the first demonstration of ultrastructural damage in the ovaries of A. persicus after infection with B. bassiana. The data presented confirm that B. bassiana affects the ovary either directly by entering the oocytes and/or indirectly by producing toxins in the haemolymph that interfere with the development of oocytes, thus potentially contributing to the control of this tick in a way that is safe for its host and the environment.