Sublethal Effects of <I>Metarhizium anisopliae</I> (Deuteromycetes) on Engorged Larval, Nymphal, and Adult <I>Ixodes scapularis</I> (Acari: Ixodidae)

Abstract

Ixodes scapularis Say adults, nymphs, and larvae were treated with the entomopathogenic fungus Metarhizium anisopliae in a combination of field and laboratory experiments to assess sublethal effects of the fungus on I. scapularis fecundity and body mass. Postengorgement and egg mass weights were 33 and 50% lower, respectively, in adult females treated with M. ansiopliae in the field before engorging on laboratory rabbits. M. anisopliae did not significantly reduce egg mass weight, conversion efficiency, or oviposition period in I. scapularis females treated with the fungus after engorging on white-tailed deer, although only 33% of treated females oviposited. Engorged nymphs and larvae treated with M. anisopliae converted significantly lower percentages of their engorged weight to their molted adult and nymphal weights. This study indicates that M. anisopliae reduces fitness (fecundity and body mass) in all active I. scapularis stages and indicates that its impact as a biocontrol agent might be higher than that suggested by direct mortality alone.

Potential effects of mixed infections in ticks on transmission dynamics of pathogens: comparative analysis of published records

“…For example, Ross and Levin (2004) found that some strains of Anaplasma phagocytophilum, the etiologic agent of granulocytic anaplasmosis in humans, affect molting of Ixodes scapularis ticks. Hornbostel et al (2004) found sublethal effects of the entomopathogenic fungus Metarhizium anisopliae on fecundity and body mass of I. scapularis. In cases of mixed infections, these pathogens could potentially influence transmission of other pathogens in the tick by virtue of their effects on tick behavior and survival.…”

Metarhizium anisopliae conidial responses to lipids from tick cuticle and tick mammalian host surface

“…is known to be pathogenic to over 200 arthropod species (Samuels et al, 1989), including animal-exploiting ectoparasites: insects, mites and ticks (Samish et al, 2004;Brooks and Wall, 2005;Scholte et al, 2006). This pathogen infects at least 15 tick species (Samish et al, 2008), killing both on-host and off-host stages (Kaaya et al, 1996;Castro et al, 1997;Kaaya, 2000;Kaaya and Hassan, 2000) and causing a variety of sub-lethal effects (Hornbostel et al, 2004;Kirkland et al, 2004b).…”

The Effect of Beauveria Bassiana on Brazilian Poplar Moth Condylorrhiza Vestigialis (Lepidoptera: Crambidae)

“…However, in the field, the spraying plants directly, affects the insect, or the insects become infected by eating or walking on the residue from the surface, varying the amount of infective propagules acquired by the host . This variation can result in a lethal or a sublethal dose, causing death or consequences on insect development, respectively (Royama 1984;Bauer and Nordin 1988b;Giustolin et al 2001;Hornbostel et al 2004). Moreover, according to our results the assessment of mortality without considering the whole cycle of the host, may underestimate the control potential of some entomopathogenic fungi.…”