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

• Published in: Journal of invertebrate pathology Vol. 103; no. 2; pp. 132 - 139
• Main Authors: Ment, Dana, Gindin, Galina, Soroker, Victoria, Glazer, Itamar, Rot, Asael, Samish, Michael
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-02-2010
• Subjects: animal cuticle; animal tissue extracts; Animals; Appressoria; Appressorium; Arthropoda; Biocontrol; biological control agents; Boophilus annulatus; calves; Cattle; conidia; Cuticle extract; cuticular lipids; entomopathogenic fungi; Fur; Germination; Host-Pathogen Interactions - physiology; host-pathogen relationships; Hyalomma; Hyalomma excavatum; lipids; Lipids - physiology; Metarhizium - physiology; Metarhizium anisopliae; Metarhizium anisopliae var. acridum; Metarhizium anisopliae var. anisopliae; Rhipicephalus ( Boophilus) annulatus; Rhipicephalus sanguineus; Skin scrape; spore germination; Spores, Fungal - physiology; tick control; Ticks - microbiology; Ticks - physiology; virulence; Fur; Hyalomma excavatum; Metarhizium anisopliae; Germination; Rhipicephalus ( Boophilus) annulatus; Cuticle extract; Appressorium; Rhipicephalus sanguineus; Biocontrol; Skin scrape
• ISSN: 0022-2011; 1096-0805
• DOI: 10.1016/j.jip.2009.12.010

Conidial germination and the formation of appressoria are important events in the interactions between entomopathogenic fungi and their arthropod hosts. In this study, we demonstrate the effects of lipids extracted from tick epicuticle and the surface of a mammalian host (calf) on conidial germination and the development of appressoria in two subspecies of
Metarhizium anisopliae,
M.
anisopliae var.
anisopliae (
M.
an.
an.-7) and
M.
anisopliae var.
acridum (
M.
an.
ac.-5), which have different levels of virulence toward ticks. Pentane extracts of epicuticles of ticks susceptible and resistant to fungal infection always stimulated the germination of
M.
an.
an.-7 conidia and the development of their appressoria; whereas the effects of dichloromethane (DCM) extracts of tick epicuticle varied depending on the tick. The DCM extracts from most of the tick species and developmental stages stimulated conidial germination and/or the formation of appressoria in
M.
an.
an.-7. However, a DCM extract of lipids from the most resistant tick, engorged
Hyalomma excavatum female, inhibited the germination of
M.
an.
an.-7 conidia. Conidia of the non-virulent
M.
an.
ac.-5 did not germinate on agarose amended with any of the examined tick extracts. However, when the tick extracts were placed on bactoagar, conidial germination increased 7- to 8-fold. Extracts from the skin, hair and ear secretions of a calf stimulated conidial germination and the formation of appressoria in
M.
an.
an.-7, but not
M.
an.
ac.-5. This study demonstrates that lipids from tick epicuticles and mammalian skin selectively affect the germination of conidia of entomopathogenic fungi. The effects of these lipids may explain the variability in tick control these fungi provide for different hosts.