# The Effect of Grain Type on Virulence of Entomopathogenic Fungi Against Stored Product Pests
## 1 Introduction  
The most common strategy for controlling insect pests in storage facilities is the application of residual or fumigant chemical insecticides [1, 2]. However, this has led to the occurrence of many problems such as environmental pollution, various dangers for applicators and consumers and emergence of pest resistance [3, 4]. All these negative side-effects drive researchers to search for alternative environmentally safe and residue-free control methods [3, 5, 6].  
Entomopathogenic fungi are considered as potential candidates to replace chemical insecticides. Their potential pathogenicity has been the focus of a significant number of studies on the use of pathogens for stored product control [7, 8, 9, 10]. Entomopathogenic fungi are microorganisms which are ubiquitous in nature and, as such, they are safe for the environment and of low toxicity to mammals [11, 12, 13]. Furthermore, they are able to develop on the cadavers, thus continuing to releasemore inoculum into the system [14; 15]. In this sense, the generated long-term effect of fungi is a desirable trait in biological control as opposed to the residual persistence of chemical pesticides [16].  
Beauveria, Metarhizium and Isaria genera are listed among the most important microbial species which are used as biological control agents and which have been documented to act against a wide range of insect hosts [17; 18; 19; 20; 10]. The fungal species which have been the most studied for their action against stored product insect pests and which have produced promising results are _Beauveria bassiana_ ([PERSON]) [PERSON] (Hypocreales: Cordycipitaceae), _Metarhizium anisopliae_ ([PERSON]) Sorokin (Hypocreales: Clavicipitaceae) and _Isaria funosorosea_ [PERSON] (Hypocreales: Clavicipitaceae) [9; 21; 22; 23; 24; 25]. The extent of entomopathogenic fungal virulence is conditioned by the interaction of several factors which involve the time of the initial host infection, the time that the disease incubation period lasts, resulting in delayed host development, the rate at which the entomopathogenic fungus spreads and several other environmental factors which are known as being conducive to epizootics [26; 27; 28].  
However, the input of other parameters such as the type of grain has been poorly studied. This factor might be related with the transmission of the pathogen to the host. Our objective was hence to investigate the effect of the grain type on the insecticidal action of three entomopathogenic fungal species, _B. bassiana_, _M. anisopliae_ and _I. fumosorosea_, on larvae of the three very common and harmful stored product pests: the khapra beetle (_Trogoderma granarium_ [PERSON]) (Coleoptera: Dermestidae), the confused flour beetle (_Tribolium confusum_ [PERSON]) (Coleoptera: Tenebrionidae) and the Mediterranean flour moth (_Ephesia kuehniella_ [PERSON]) (Lepidoptera: Pyralidae), on four different grains such as _Triticum aestivum_ L. (wheat) (Poales: Poaceae), _Oryza sativa_ L. (rice) (Poales: Poaceae), _Aractis hypogaea_ L. (peanuts) (Fabales: Fabaceae) and _Vicia fuba_ L. (beans) (Fabales: Fabaceae). Our results are discussed within the framework of employing entomopathogenic fungi as biocontrol agents against stored product pests.