Environmental stress conditions compromise the effectiveness of microorganisms for use in biological control. We investigated the thermotolerance of seven Metarhizium isolates from Central Brazil to 32 °C, and the thermotolerance of conidia of Metarhizium anisopliae s.str. IP 119 (Metchnikoff) (Hypocreales: Clavicipitaceae) and M. robertsii formulated in oil-in-water emulsion to 45 °C. We also evaluated the efficacy of oil-formulated conidia of M. anisopliaes.str. IP 119 against the tick Rhipicephalus microplus (Canestrini) (Acari: Ixodidae) under stress conditions (32 °C; 75% RH). The conidial germination on tick’s cuticle was assessed by Scanning Electron Microscopy. Conidia of M. anisopliaes.str. IP 119 formulated in oil-in-water emulsion caused significant control (59.4%) of R. microplus, even when treated ticks were incubated under stress (32 °C; 75% RH). Metarhizium spp. incubated at 32 °C had both decreased radial growth and conidial production. Conidia of IP 119 formulated in oil-in-water emulsion were more tolerant to 45 °C than conidia suspended in water. An oil-in-water emulsion protected M. anisopliaes.str. conidia against heat and dry conditions and may enhance its efficacy to control ticks by improving the tolerance of fungi against adverse environmental factors.

中文翻译：

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热和干燥条件下水包油乳状菌中的异化分生孢子分生孢子对微小的Rhipicephalus microplus虱的功效

环境压力条件损害了用于生物防治的微生物的有效性。我们调查的七耐热绿僵菌从巴西中部隔离至32℃，分生孢子的耐热金龟子绿僵菌s.str。IP 119（Metchnikoff）（Hypocreales：Clavicipitaceae）和罗伯特氏菌（M. robertsii）在水包油乳液中配制至45°C。我们还评估了M. anisopliae s.str。IP 119在压力条件下（32°C; 75％RH）对抗壁虱Rhipicephalus microplus（Canestrini）（Acari：Ixodidae）。通过扫描电子显微镜评估tick的角质层上的分生孢子萌发。分生孢子M. anisopliae s.str。即使在应力（32°C; 75％RH）下温育处理过的s，即使在水包油型乳剂中配制的IP 119仍可显着控制（59.4％）微小micro。绿僵菌。在32°C孵育时，径向生长和分生孢子减少。与水悬浮的分生孢子相比，在水包油型乳剂中配制的IP 119分生孢子对45°C的耐受性更高。水包油乳液保护的M. anisopliae s.str。分生孢子可以抵抗高温和干燥条件，并且可以通过提高真菌对不利环境因素的耐受性来增强其控制tick虫的功效。