Endophytic and entomopathogenic strains of Beauveria sp to control the bovine tick Rhipicephalus (Boophilus) microplus

Abstract

ABSTRACT. Pathogenicity of strains of the entomopathogenic fungus Beauveria bassiana and endophytic strains of Beauveria sp against the bovine tick Rhipicephalus (Boophilus) microplus was tested in laboratory bioassays and under field conditions. Suspensions containing 10 5 , 10 7 and 10 9 conidia/mL were prepared of each fungal strain for laboratory bioassays. The ticks were maintained at 28°C, 90 ± 5% relative humidity, and the following variables were evaluated: initial female weight, egg weight, hatching percentage, reproductive efficiency, and percentage control. For tests under field conditions, a Beauveria suspension containing 10 6 conidia/mL was sprayed on tick- infested cows. After 72 h, the ticks were collected to estimate mortality under field conditions. Laboratory bioassays showed a mortality of 20 to 50% of the ticks seven days after inoculation with 10 7 Beauveria conidia/mL. Under field conditions 10 6 Beauveria conidia/mL induced 18-32% mortality. All Beauveria strains were effective in biological control of R. (Boophilus) microplus under laboratory and field test conditions. This is the first demonstration that endophytic fungi can be used for biological control of the cattle tick; this could help reduce environmental contamination by diminishing the need for chemical acaricides. Two endophytic strains were isolated from maize leaves and characterized by molecular sequencing of 5.8S rDNA ITS1 and ITS2 and morphological analyses of conidia. We found that these two endophytic Beauveria isolates, designated B95 and B157, are close to Beauveria amorpha.

In vitro Efficacy of Verticillium lecanii and Beauveria bassiana of Commercial Source Against Cattle Tick, Rhipicephalus (Boophilus) annulatus

“…It was known that tick larvae were the most susceptible than other stages (Camargo et al, 2012). The present result is similar to those reported by Cafarchia et al, (2015) but they encountered 100% mortality of larvae at 15 days PA. On other hand, several studies reported lower mortalities rates than the rate of present study (Kaaya and Hassan 2000;Reis et al, 2005;Campos et al, 2010). We think that the technique of application, larval age and tick species may be the causes of this variation.…”

Biological control of engorged female Haemaphysalis qinghaiensis (Acari: Ixodidae) ticks with different Chinese isolates of Beauveria bassiana

“…Moreover, we found that the mortality rate reached 55.25% at only 6 days after inoculation with 10 8 Beauveria conidia mL −1 . Likewise, when R. microplus were treated with B. bassiana and M. anisopliae (Campos et al 2010;Frazzon et al 2000), the most virulent strains were able to induce mortality in up to 50% of the tick population by 7 and 5 days after treatment, respectively.…”

Control biológico de Rhicephalus (Boophilus) microplus con hongos entomopatógenos / Biological Control of Rhicephalus (Boophilus) microplus with Entomopathogenic Fungi

“…Estos estudios coinciden con el presente, respecto a la eficacia de lo cual varía dependiendo de la cepa y la concentración utilizada. Según Frazzon et al (2000), Kirkland et al (2004) y R.A. Campos, et al (2010), esta diferencia en la eficacia depende de la capacidad de la cepa del hongo para penetrar la cutícula de la garrapata, usando una combinación de mecanismos enzimáticos y físicos. No obstante, aunque se cuenta con un considerable volumen de información sobre estudios realizados con Metarhizium anisopliae para el control de garrapatas Ricephalus (Boophilus) microplus, no ocurre lo mismo para el hongo de Beauveria bassiana, del cual, a excepción del trabajo publicado por Ren et al (2011), donde evalúa la virulencia de varias cepas chinas de este hongo, se cuenta con poca información específica publicada para el control de garrapatas Ricephalus (Boophilus) microplus.…”