ABSTRACT

Temperature critically affects the performance of entomopathogenic fungi (EPF). Mathematical models are critical tools used in predictive microbiology but are less adopted for EPF. We selected eight nonlinear models to describe thermal biology; minimum (T_min), optimal (T_opt) and maximum (T_max) thresholds; and maximal growth (P_max) of EPF. Conidial germination and mycelial growth of Metarhizium anisopliae (ICIPE 7, ICIPE 20, ICIPE 62, ICIPE 69, ICIPE 78) and Beauveria bassiana (ICIPE 284) isolates incubated at 12, 16, 20, 24, 28, 32 and 36°C were measured and fitted to the models. The models were compared using the Akaike information criterion (AIC) and adjusted R². The best–fitting models for germination of the isolates were the cardinal temperature model with inflection (CTMI), Ratkowsky 3 and the generalised β function, while the best–fitting models for growth were CTMI, Ratkowsky 3, Lactin 1 and generalised β function. Brière 1, Brière 2, Ratkowsky 2, and Van Der Heide least fitted most germination and growth datasets. T_min, T_opt, T_max and P_max ranged from 13.3–13.6°C, 26.3–28.1°C, 35.7–36.3°C and 95.4–100.0% for germination, and 3.7–13.7°C, 25.9–28.6°C, 35.4–37.2°C and 1.44–2.34 mm day^–1 for growth, respectively. T_opt were below temperatures of central bee brood areas and partly mirrored temperatures of the isolates’ regions of origin. The best–fitting models can be used to better match EPF with different regions’ temperatures for optimal performance against target pests.

摘要

温度严重影响昆虫病原真菌 (EPF) 的性能。数学模型是预测微生物学中使用的关键工具，但很少用于 EPF。我们选择了八个非线性模型来描述热生物学；最小 ( T _min )、最佳 ( T _opt ) 和最大 ( T _max ) 阈值；和 EPF 的最大增长 ( P _max )。绿僵菌（ICIPE 7、ICIPE 20、ICIPE 62、ICIPE 69、ICIPE 78）和白僵菌的分生孢子萌发和菌丝体生长(ICIPE 284) 在 12、16、20、24、28、32 和 36°C 下培养的分离物被测量并拟合到模型中。使用 Akaike 信息标准 (AIC) 比较模型并调整 R ²。分离株萌发的最佳拟合模型是具有拐点 (CTMI)、Ratkowsky 3 和广义 β 函数的基本温度模型，而生长的最佳拟合模型是 CTMI、Ratkowsky 3、Lactin 1 和广义 β 函数。Brière 1、Brière 2、Ratkowsky 2 和 Van Der Heide 最不适合大多数发芽和生长数据集。T _min , T _opt , T _max和P _max发芽温度范围为 13.3–13.6°C、26.3–28.1°C、35.7–36.3°C 和 95.4–100.0%，发芽温度范围为 3.7–13.7°C、25.9–28.6°C、35.4–37.2°C 和 1.44–2.34 mm第^–1天分别表示增长。T _opt低于中央蜂巢区域的温度，部分反映了分离株起源区域的温度。最佳拟合模型可用于更好地将 EPF 与不同地区的温度相匹配，以获得针对目标害虫的最佳性能。