Susceptibility of different populations of ticks to entomopathogenic fungi

• Published in: Experimental parasitology 2012-03, Vol.130 (3), p.257-260
• Main Authors: Perinotto, W.M.S., Angelo, I.C., Golo, P.S., Quinelato, S., Camargo, M.G., Sá, F.A., Bittencourt, V.R.E.P.
• Format: Article
• Language: English
• Subjects: Animals; Beauveria - physiology; Beauveria bassiana; bioassays; Biologic control; Biological Assay; Boophilus microplus; Cattle; Cattle Diseases - parasitology; Cattle Diseases - prevention & control; demonstration farms; egg production; eggs; entomopathogenic fungi; Female; females; hatching; Larva - microbiology; larvae; Metarhizium - physiology; Metarhizium anisopliae; mortality; Ovum - microbiology; parasitology; Pest Control, Biological - methods; Rhipicephalus - classification; Rhipicephalus - microbiology; Rhipicephalus - physiology; Rhipicephalus microplus; Susceptibility; Tick Infestations - prevention & control; Tick Infestations - veterinary; ticks; virulence
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1016/j.exppara.2011.12.003

[Display omitted] ► Evaluation of the in vitro fungal action on two Rhipicephalus microplus populations. ► Bioassays were performed with engorged females, eggs and larvae. ► Ticks from FAIZ were more susceptible to the fungal infection than the PESAGRO ticks. ► Tick population’s susceptibility also affects the efficacy of biological control. This study aimed to evaluate the in vitro effect of the entomopathogenic fungi Metarhizium anisopliae sensu lato (s.l.) and Beauveria bassiana sensu lato (s.l.) on two distinct populations of Rhipicephalus microplus, from two different experimental farms. Bioassays were performed with engorged females, eggs and larvae. Fungal infection was evaluated based on biological parameters of treated engorged females, percentage of hatch from treated eggs, and percentage of mortality and mean lethal time (LT90) of treated larvae. When the treatments were compared between the two populations, there were significant differences in the following parameters: pre-oviposition period, hatching period and egg production index. Moreover, the results showed that B. bassiana s.l., isolate Bb 986, was more virulent than M. anisopliae s.l., isolate 959, for engorged females, showing a control percentage of 49%. In the bioassay with eggs, the hatching percentage ranged from 3.1% to 49.5% in one population and from 3.4% to 42.7% in the other, with no significant difference between the two populations. In the bioassay with unfed larvae, the mortality percentage ranged from 91.8% to 98.7% in one population and from 71.0% to 94.0% in the other. The LT90 varied from 19.52 to 27.51days in one of the populations and 22.89 to 37.31days in the other. These results suggest that populations of R. microplus show distinct variation in their susceptibility to B. bassiana s.l. and M. anisopliae s.l.