Metarhizium anisopliae as a Biological Control Agent Against Hyalomma anatolicum (Acari: Ixodidae)

Abstract

In the Sudan, ticks and Tick-borne Diseases (TBDs) with subsequent costs of control and treatment are causing substantial economic loss. Control of ticks is mainly by chemical insecticides. The rising environmental hazards and problem of resistance has motivated research on biological agents as alternative methods of control. The present study aims at controlling livestock ticks using fungi for their unique mode of action besides their ability to adhere to the cuticle, to germinate and penetrate enzymatically. The study was conducted to evaluate the fungus Metarhizium anisopliae for tick control as an alternative mean to chemical acaricides. Pathogenicity of the fungus was tested on different developmental stages of the tick Hyalomma anatolicum. The fungus induced high mortality to flat immature stages. It, also, affected reproductive potential of the females. Egg laid, hatching percent, fertility and moulting percent of immature stages were significantly (p < or = 0.05) reduced. It was, also, shown that the fungus had ability to adhere to the cuticle and penetrate the integument of the tick. Conidia of the fungus were isolated from their internal tissues. This phenomenon is important in considering fungi as bioinsecticides. Infection of eggs laid by treated engorged female ticks, with the fungus might demonstrate suggesting transovarian transmission. The use of M. anisopliae to control ticks is discussed.

Integrative Alternative Tactics for Ixodid Control

“…Although most fungal infections of ixodids occur by direct contract, Suleiman et al [ 427 ] suggested that transovarian transmission is also possible. Fungal entomopathogens, such as M. anisopliae , typically weaken the cuticle with histolytic enzymes [ 333 , 427 ], which sometimes ruptures, and mortality occurs as infected areas of the cuticle enlarge over ≥50% of the body surface area [ 412 , 428 , 429 , 430 ]. Lethal expansion of weakened parts of the cuticle can be relatively rapid, within 48 h under optimal ambient conditions [ 430 ].…”

“…In addition, M. anisopliae -infected I. scapularis larvae and nymphs molted into their next life stages with weight reductions [ 397 ]; overall, fungal infection results in decreased ixodid fitness for survival [ 397 ]. Reduced egg production and hatching occurred after engorged R. microplus adults were treated with a commercial Metarhizium -based product [ 454 ], and M. anisopliae applied on female H. anatolicum reduced numbers of deposited eggs, hatching, and percent of molting offspring [ 427 ]. Sun et al [ 399 ] reported that B. bassiana applied to engorged female R. microplus reduced oviposition, although most of the females died before laying eggs.…”

Towards a Sustainable One Health Approach to Crimean–Congo Hemorrhagic Fever Prevention: Focus Areas and Gaps in Knowledge

“…Metarhizium anisopliae is the most well-studied fungal pathogen of arthropods and is considered to particularly promising due to posing minimal risk to non-target organisms. M. anisopliae has been shown to effectively control nymphal Ixodes tick [ 147 ], cattle tick [ 148 , 149 , 150 ], and Hyalomma tick populations by inducing high mortality in immature stages and decreasing reproductive fitness in females [ 151 ].…”

The control of Hyalomma ticks, vectors of the Crimean–Congo hemorrhagic fever virus: Where are we now and where are we going?

“…anisopliae against all stages of H . anatolicum collected in Sudan was then confirmed [ 83 ], as well as that of Scopulariopsis brevicaulis against adult tick stages [ 84 ]. Finally, a study demonstrated, in vitro, an effective ovicidal effect of proteases produced by Aspergillus sojae and A .…”