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

Abstract

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. Tick populations and fungal efficacy were highest at the peaks of rainfall and relative humidity or soon thereafter. Fed and unfed adult R. e. evertsi and R. (B.) decoloratus collected at the end of the experiment from the fungus-sprayed and from the control cattle and incubated in the laboratory exhibited a mortality of 93% in oil formulated conidia and 14% in oil control. The corresponding mortality in R. (B.) decoloratus was 100% in fungus and 11% in oil control. Ticks on the fungus-sprayed groups had significantly higher mortality (P < 0.05) than on the control groups. Furthermore, no significant difference (P < 0.05) was observed in fungus-induced mortality between the two tick species. Mortalities induced by Triton X-100 (0.05%), sunflower oil (20%) and water alone were low, suggesting that they were non-toxic to ticks at the concentrations used and no significant difference was observed among them. No physical or behavioral abnormalities were observed in the fungus-sprayed cattle at any time during the course of the experiment. All groups of cattle gained weights during the experimental period.

Efficacy of <em>Metarhizium anisopliae</em> in the control of the horn fly, <em>Haematobia irritans</em> (<em>Diptera: Muscidae</em>), under natural infestation conditions

“…34 The use of multiple applications of an Original Research entomopathogenic fungus provides better results. 30,33 The results obtained in this study confirm the potential of M. anisopliae to infect and cause death in H. irritans under natural infestation conditions. Because the infestation by the horn fly in the region under study is seasonal, it would be advisable to start a control programme using this formulation when the first detection occurs to limit the fly population growth.…”

“…Other authors reported similar findings in cattle infested with ticks or stable flies and treated with M. anisopliae formulations under field conditions. 25,33,34 The homogenous weather conditions in the study period and an ad- Original Research equate combination of humidity and temperature were ideal for the development and maintenance of the population curve of H. irritans. However, at the end of the study, the change in these environmental conditions, especially the low average daily temperature, favoured a decline in the infestation of flies.…”

Commercial formulation of Metarhizium anisopliae for the control of Rhipicephalus microplus in a pen study

“…It is believed that this efficacy can be enhanced with the development of a treatment protocol, i.e., by establishing a number of animal baths with fungal formulations for a period of time. This theory was strengthened by Kaaya et al (2011), who evaluated the effect of an oil formulation of M. anisopliae by spraying it once every three weeks for one year in cattle infested with ticks Rhipicephalus evertsi evertsi and Rhipicephalus (Boophilus) decoloratus under field conditions. These researchers observed a reduction of up to 83% of tick populations.…”

“…Among acaripathogenic fungi, Beauveria and Metarhizium have been the most studied genera for tick control (Fernandes et al, 2012). Several studies have demonstrated the importance of using these fungi in a formulation, not just suspended in water, for controlling ticks (Kaaya, 2000;Kaaya and Hassan, 2000;Maranga et al, 2005;Polar et al, 2005;Alonso-Díaz et al, 2007;Souza et al, 2009;Ángel-Sahagúna et al, 2010;Kaaya et al, 2011). Some of these studies evaluated the fungal formulations against ticks through in vivo tests; however, more studies are required to obtain formulations that maintain the viability and efficacy of acaripathogenic fungi for tick control in the field.…”

Does Cattle Milieu Provide a Potential Point to Target Wild ExophilicAnopheles arabiensis(Diptera: Culicidae) with Entomopathogenic Fungus? A Bioinsecticide Zooprophylaxis Strategy for Vector Control

“…Third, this is the first study to apply fungus on cattle for the control of malaria vectors, and therefore we could have underdose mosquitoes. We sprayed the whole body of a calf with a fungal conidia dose of 1.0 − 2.2 × 10 9 conidia mL −1 which was slightly higher than the dose tested (1 × 10 8 conidia mL −1 ) on cattle to control ticks [60, 61]. However, ticks are sticking on cattle body for days while feeding until become engorged whereas mosquitoes fly and land on cattle body to feed for few minutes (temporary ectoparasites).…”