Trials to Control South American Ticks with Entomopathogenic Fungi

Abstract

Ticks are parasites of great importance to man, domestic, and wild animals. In spite of the progress of the science, thus far, ticks are controlled mainly by chemical acaricides and when this technique is used in an indiscriminate way it can lead to ambiental pollution and development of tick resistance to acaricides. The studies developed in the Universidade Federal Rural do Rio de Janeiro demonstrate that some isolates of the fungi Metarhizium anisopliæ and Beauveria bassiana are pathogens for ticks and their action effects the mortality of ticks and reduces the populational levels in subsequent generations. In future, research needs to address the search of new pathogens; the association of biological with chemical products seeking an synergistic action; the search of formulations that propitiate increased stability, and careful studies on the safety of biological products for use in animals.

Physiological effects upon Amblyomma americanum (Acari: Ixodidae) infected with Beauveria bassiana (Ascomycota: Hypocreales)

“…In this condition they would not be able to access a host. This observation supports the contention by Yoder and Spielman (1992) that an inability to climb vegetation may explain the paucity of infected ticks collected in the field, as noted by Bittencourt (2000) and Chandler et al (2000). Even if ticks accessed a host they would probably be so disabled that attachment using extension of chelicerae to penetrate host skin would be problematical.…”

“…Further work is needed to determine if the impact on water balance translates into behavioral changes in the field. Infection-induced water loss may account for some of the pathological effects such as sluggishness (Mwangi et al 1995), and limited egg-laying potential (Bittencourt 2000;Gindin et al 2002;Samish et al 2001) noted earlier. The varied responses by ticks to fungal exposure, as highlighted by Ostfeld et al (2006), may in part be explained by the impact on water balance and the varied ability to remain hydrated.…”

Virulence of Mexican isolates of entomopathogenic fungi (Hypocreales: Clavicipitaceae) upon Rhipicephalus=Boophilus microplus (Acari: Ixodidae) larvae and the efficacy of conidia formulations to reduce larval tick density under field conditions

“…Fungi such as Metarhizium anisopliae (Metschnickoff) Sorokin, Cordyceps (Beauveria) bassiana (Balsamo) Vuillemin, Lecanicillium lecanii (=Verticillium lecanii) (Zimmermann) Zare and W. Gams, and Paecilomyces = Isaria fumosorosea (Wize) Brown and Smith have been studied as control agents of ticks (Bittencourt et al, 1992;Souza et al, 1999;Kaaya and Hassan, 2000;Bittencourt, 2000;Gindin et al, 2001;Samish et al, 2001Samish et al, , 2004aFernandes et al, 2003Fernandes et al, , 2006aFernández-Ruvalcaba et al, 2005;Polar et al, 2005a,b;Beltrán et al, 2008). Studies on the potential of entomopathogenic fungi as tick control agents have been conducted mainly as laboratory assays (Polar et al, 2005c;Leemon and Jonsson, 2008).…”

Intracellular infection of tick cell lines by the entomopathogenic fungus Metarhizium anisopliae

“…These include tick species from a wide range of genera that are of economic, medical and veterinary importance such as Amblyomma, Rhipicephalus (Boophilus) and Ixodes (Fernandes et al, 2003;Kirkland et al, 2004b;Pirali-Kheirabadi et al, 2007). Indeed, specific application methods have been developed for use of entomopathogenic fungi against Ixodes scapularis, the carrier of the Lyme-disease-causing spirochaete Borrelia burgdorferi, and various livestock ticks, such as Rhipicephalus (Boophilus) microplus and Amblyomma variegatum (Benjamin et al, 2002;Bittencourt, 2000;Kaaya, 2000;Maranga et al, 2006). Some tick species, such as Dermacentor variabilis and Amblyomma americanum, display a level of resistance to fungal infection that can be overcome by specific inoculation conditions that modify the chemical and structural composition of the cuticle (Kirkland et al, 2004a(Kirkland et al, , 2005.…”