Heat-stressed Metarhizium anisopliae: viability (in vitro) and virulence (in vivo) assessments against the tick Rhipicephalus sanguineus

详细信息    查看全文

• 作者：Fabrício M. Alves ; Cíntia C. Bernardo ; Flávia R. S. Paixão…
• 关键词：Entomopathogenic fungi ; Thermotolerance ; Formulated fungi ; Commercial bioproduct ; Metarril ; Tick control
• 刊名：Parasitology Research
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：116
• 期：1
• 页码：111-121
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Medical Microbiology; Microbiology; Immunology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-1955
• 卷排序：116

文摘

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.