anisopliae s.l. Ma 959 isolate

and B. bassiana Bb 986 isolate on R. microplus population BMS-777607 ic50 ( Table 4). It is important to note that the treatments of each tick developmental stage was carried out separately, accordingly the cumulative effect is hypothetical, assuming that the combined treatments would be equivalent. The present study showed that the addition of mineral oil to formulations of M. anisopliae, isolate Ma 959, and B. bassiana, isolate Bb 986, enhanced the pathogenic effects of these fungi against different stages of R. microplus. Mineral and vegetable oils are used in formulations as adjuvants to protect conidia and to maximize fungal performance ( Alves, 1998). In the present study, the pathogenic activity of M. anisopliae s.l. against developmental stages of R. microplus was enhanced by formulating the fungus with mineral oil. Our findings are in agreement with the data reported by Angelo et al. (2010). They evaluated learn more a 15% oil-based formulation of Lecanicillium lecanii and found significant differences on all R. microplus tick stages. The cuticle

of most arthropods has hydrophobic characteristics as do some entomopathogenic conidia isolates ( Prior et al., 1988). Thus, conidia suspended in water tend to show hampered adherence to the host cuticle. In the present study, the oil-based formulations of M. anisopliae s.l. and B. bassiana were more effective on R. microplus than the aqueous suspensions. These results can be explained by the increased adherence of conidia on the cuticle provided by the oil adjuvant present in the formulations, which has a chitinophilic property. This property of oil increases the affinity of hydrophobic conidia for the tick’s cuticle, which enhances the infectivity and consequently the pathogenicity of fungal isolates ( Prior et al., 1988). Rolziracetam The chitinophilic characteristic of oil likely accelerated the infection process of the fungi used in the present study since the oil formulation caused faster damage to engorged females, eggs,

and larvae than the water based fungi suspensions. Fernandes et al. (2011) evaluated the virulence of 60 Beauveria spp. isolates on the immature stages of R. microplus and noted that larvae from different populations showed different susceptibility to the isolates tested. Moreover, differences in the susceptibility of two distinct R. microplus populations infected with B. bassiana and M. anisopliae was observed (unpublished data). Thus, the difference between results presented here using R. microplus engorged females infected with B. bassiana isolate 986 and those reported in the literature may be related to variations in susceptibility of distinct tick populations to the same fungal isolate.