Influence of Temperature and Relative Humidity on the Insecticidal Efficacy of Metarhizium anisopliae against Larvae of Ephestia kuehniella (Lepidoptera: Pyralidae) on Wheat

Abstract

A series of laboratory bioassays were conducted for the evaluation of the insecticidal efficacy of an isolate of Metarhizium anisopliae (Metschnikoff) Sorokin (Ascomycota: Hypocreales) against larvae of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), under various temperature–relative humidity (r.h.) conditions. The fungus was applied at four doses (0, 8 × 106, 8 × 108, and 8 × 1010 conidia ml−1) on wheat and insect mortality was assessed after exposure of 1, 2, 7, and 14 d. Bioassays were conducted at three temperatures (20, 25, and 30 °C) and two r.h. levels (55 and 75%). Although complete control was not achieved in any case, the fungus provided a considerable level of insect control. Mortality of E. kuehniella larvae on wheat treated with M. anisopliae ranged between 41.1 and 93.3% after 14 d of exposure, whereas the respective mortality levels in control dishes never exceeded 28.3%. The increase of temperature resulted in most cases to higher efficacy, indicating that temperature is an important factor for the performance of the fungus. In contrast, in most cases r.h. did not significantly affect the efficacy of the fungus, at least for the humidity levels tested.

Efficacy of the entomopathogenic fungi; Beauveria bassiana and Metarhizium anisopliae against the cowpea weevil, Callosobruchus maculatus F. (Coleoptera: Chrysomelidae: Bruchinae)

“…Among EPF, the biological control potential of Beauveria bassiana (Bals.) Vuill., Metarhizium anisopliae (Metch) Sorok, and Isaria fumosorosea Wize has been studied against various pests, in particular, C. maculatus (Vilas Boas et al 1996;Rice and Cogburn 1999;Padin et al 2002;Batta 2005;Cherry et al 2005Cherry et al , 2007Sewify et al 2014;Athanassiou et al 2017;Iqbal et al 2018).…”

The Effect of Grain Type on Virulence of Entomopathogenic Fungi Against Stored Product Pests

“…It was reported that the treatment of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) with B. bassiana caused more than 80% mortality to adult insects which had been reared on three types of nutritional substrates, 21 days post-treatment [37]. Moreover, M. anisopliae isolates tested on wheat produced a significant rate of E. kuehniella larval mortality, exceeding 90%, 14 days after exposure [38]. By contrast, it was reported that the treatment of E. kuehniella with M. anisopliae, B. bassiana and Lecanicillium lecanii (Zimm.)…”

Decision Support System for Fitting and Mapping Nonlinear Functions with Application to Insect Pest Management in the Biological Control Context

“…However, it will be useful to explore the association of temperature with other factors such as relative humidity to improve the accuracy of the prediction, especially for mapping the virulence level of the EPF. Indeed, many studies highlighted the key role played by both temperature and relative humidity in enhancing the virulence of EPF on insect pests [47][48][49]. On this note, a good perspective to consider for improving the current tool will be to consider the association of at least two factors (temperature and relative humidity, for example) as independent variables in the fitting process.…”