# The Effect of Grain Type on Virulence of Entomopathogenic Fungi Against Stored Product Pests
## 4 Discussion  
The results of the present study may be of increased interest as the environmental safety of an insecticide is today considered to be of paramount importance. Fungi have a specific role in pest control, having high persistence in the environment. Some entomopathogenic fungi affect a limited range of hosts, while other species have a wider host range, i.e., _M. anisopliae, I. fumosorosea_ and _B. bassiana_. Although several published data exist regarding the efficacy of entomopathogenic fungi against stored-grain insect pests [22; 33; 34; 32; 23], there is a lack of references addressing the effect of the product type on the efficacy of these fungi. The insecticidal degree of entomopathogenic fungi is interdependent with several factors such as the behavior of the insect, its age, nutrition, genetic profile, the density of its population, as well as the extent of host sensitivity to biological control agents, due to host physiology and morphology [35]. Therefore, it would not be accurate to attribute differences in the vulnerability of the storage beetle to  
Figure 4: Seed weight (g \(\pm\) SD) of wheat, rice, beans and peanuts treated with 10\({}^{8}\) spores mL\({}^{-1}\) of _B. bassiana_ (strain name: GBBSTTS), _I. fumosorosea_ (strain name: RHZ4 RAS) and _M. anisopliae_ (strain name: Z3 RAS), after infestation with _T. confusum_ larvae for 10 days. entomopathogenic fungi merely to the applied conidial concentration [36]. Our results point to the fact that variation in the efficacy of entomopathogenic fungi was a result of both the product and the isolates. On peanut seeds, our treatment of _T. granarium_ with different species of entomogenic fungi indicated high levels of larval mortality 10 days after treatment. On wheat, rice and bean seeds, however, larval mortality was at moderate levels. The lowest overall mortality of _E. kuelniella_ larvae was detected on rice seeds, while the highest was recorded on peanut seeds 10 days after treatment. The overall mortality of _T. confusum_ larvae was the lowest on rice seeds and on peanut seeds, 10 days following treatment. 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. kuelniella_ larval mortality, exceeding 90%, 14 days after exposure [38]. By contrast, it was reported that the treatment of _E. kuelniella_ with _M. anisopliae_, _B. bassiana_ and _Lecanicillium lecanii_ ([PERSON]. [PERSON] & [PERSON] (Hypocreales: Cordycipitaceae) on wheat produced very low mortality rates (\(<70\%\)) [39]. A comparison of the cited studies with our own results suggests that different isolates and different products can have dissimilar effects on _E. kuelniella_, _T. confusum_ and _T. granarium_ larvae. Apparently, product is a favorable factor to be considered in the selection of suitable fungi for the control of serious stored-product pests, as suggested by the median lethal time of larvae in relation to the products. The median lethal time of larvae was the lowest on peanut seeds, and it was the highest on rice seeds. Our results are certainly encouraging for the integrated control of _E. kuelniella_, _T. confusum_ and _T. granarium_ larvae, but the combined application of virulent fungal isolates with the suitable product may also be practically used to reinforce the control of other stored grain insect pests. It has been reported that treating stored wheat grains with _B. bassiana_ resulted in a reduction of the total grain weight loss caused by _S. oryzae_ (L.) infestation in the storage facility [40]. Grain loss related to storage insects has been studied mainly in short laboratory tests [41; 42; 43]. All the products which had been infested with _E. kuelniella_, _T. confusum_ and _T.