title: Heat-stressed Metarhizium anisopliae: viability (in vitro) and virulence (in vivo) assessments against the tick Rhipicephalus sanguineus.
abstract: The current study investigated the thermotolerance of Metarhizium anisopliae s.l. conidia from the commercial products Metarril® SP Organic and Metarril® WP. The efficacy of these M. anisopliae formulations against the tick Rhipicephalus sanguineus s.l. was studied in laboratory under optimum or heat-stress conditions. The products were prepared in water [Tween® 80, 0.01 % (v/v)] or pure mineral oil. Conidia from Metarril® SP Organic suspended in water presented markedly delayed germination after heating to constant 40 °C (for 2, 4, or 6 h) compared to conidia suspended in mineral oil. Metarril® SP Organic suspended in oil and exposed to daily cycles of heat-stress (40 °C for 4 h and 25 °C for 19 h for 5 consecutive days) presented relative germination of conidia ranging from 92.8 to 87.2 % from day 1 to day 5, respectively. Conversely, germination of conidia prepared in water ranged from 79.3 to 39.1 % from day 1 to day 5, respectively. Culturability of Metarril® WP decreased from 96 % when conidia were cultured for 30 min prior to heat exposure (40 °C for 4 h) to 9 % when conidia were cultured for 8 h. Tick percent control was distinctly higher when engorged females were treated with oil suspensions rather than water suspensions, even when treated ticks were exposed to heat-stress regimen. Oil-based applications protected fungal conidia against heat-stress. Although Metarril® is not registered for tick control, it may be useful for controlling R. sanguineus, especially if it is prepared in mineral oil.
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, GO, 74690-900, Brazil.
authors.forename: Fabrício M
authors.initials: FM
authors.lastname: Alves
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, GO, 74690-900, Brazil.
authors.forename: Cíntia C
authors.initials: CC
authors.lastname: Bernardo
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, GO, 74690-900, Brazil.
authors.forename: Flávia R S
authors.initials: FR
authors.lastname: Paixão
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, GO, 74690-900, Brazil.
authors.forename: Lucas P
authors.initials: LP
authors.lastname: Barreto
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, GO, 74690-900, Brazil.
authors.forename: Christian
authors.initials: C
authors.lastname: Luz
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, GO, 74690-900, Brazil.|Emerging Pest and Pathogens Research Unit, US Department of Agriculture, Agriculture Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY, 14853-2901, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Humber
authors.affiliation: Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Avenida Esperança s/n, Campus Samambaia, Goiânia, GO, 74690-900, Brazil. evertonkort@ufg.br.
authors.forename: Éverton K K
authors.initials: ÉK
authors.lastname: Fernandes
mesh_terms: D000818:Animals; D005260:Female; D006358:Hot Temperature; D052981:Metarhizium / Q000254:growth & development* / Q000472:pathogenicity; D010572:Pest Control, Biological / Q000379:methods*; D048508:Rhipicephalus sanguineus / Q000382:microbiology*; D013172:Spores, Fungal / Q000254:growth & development / Q000472:pathogenicity; D013983:Tick Control / Q000379:methods*; D014774:Virulence
keywords: Commercial bioproduct; Entomopathogenic fungi; Formulated fungi; Metarril; Thermotolerance; Tick control