# Could _Gnomoniopsis castaneae_ Be Used as a Biological Control Agent against Insect Pests?
## 4 Discussion  
Although EPFs are already available for commercial use [35; 36; 37; 38; 39; 40], basic and applied research is still necessary to improve their virulence and enhance their role in Integrated Pest Management (IPM). Although the original habitat underlines the pathogenicity of EPF species [41], evaluation assays of potential isolates should not be targeted only at the original host, but also at various insect pests, as it was clearly indicated by our results. We used two major stored product pests for experimentation, because there is a plethora of publications on the effect of EPF species against insect pests of stored products, often with contradictory results [2; 37; 40; 42; 43; 44; 45; 46; 47; 48; 49; 50]. [PERSON], et al. [51] stated that the entomophogen _Isaria farinosa_ achieved high pathogenic activity on the citrus mealybug, especially under humid conditions, and caused high mortality within six days of incubation. Also, [PERSON], et al. [46] showed that different isolates of _M. anisopliae_ and _B. basiana_ can achieve a satisfactory control of _Callosobruchus maculatus_ (F) (Coleoptera: Bruchidae) by immersion bioassay at 12 d, whereby _B. basiana_ proved more virulent than _M. anisopliae_. [PERSON], et al. [47] claimed _B. basiana_ to be successful against stored wheat pests. In a similar vein, [PERSON], et al. [48] and [PERSON], et al. [49] reported that some _B. basiana_ isolates can achieve 100% mortality of the organophosphate resistant strain of _Oryzaaephilus surinamensis_ (L.) (Coleoptera: Silvanidae) after 10 d of treatment at 1 \(\times\) 10\({}^{8}\) conidia/mL. In older studies, the mortality of stored grain pests reached 80-100% after 10-20 t the ina same doses [2; 50]. [PERSON], et al. [52] showed that the efficacy of _M. anisopliae_ and B. basiana_, was over 90% on treated larvae of the African tephritid fruit fly. We used _I. fumosorosea_ as a positive control given that it has demonstrated noteworthy virulence (70-100%) in numerous studies against many insect pests [53; 54; 55] and has often exhibited the highest pathogenicity in comparison with other EPF species [56]. The current study mainly focused on the entomophogenic potential of _G. castaneae_ in comparison with that of _I. fumosorosea_. Although _Genomonopsis castaneae_ proved to be entomophogenic, it caused low pathogenicity to _M. persicae_ and _T. granarium_, but significant mortality levels, especially at the highest conidial concentration, to _P. interpunctella_. On the other hand, the _I. fumosorosea_ native strain caused a mortality of 86.7% to _P. interpunctella_, 86.7% to _M. persicae_, and 73.3% to _T. granarium_ at high conidial doses. On the other hand, [PERSON], et al. [57] found that _I. fumosorosea_ was not effective against adults and larvae of _Tribolium confusum_ (Coleoptera: Tenebrionidae) [PERSON] and of _Ephestia kuehniella_ Zeller (Lepidoptera: Pyralidae). The dependency of a fungal disease on conidial concentration normally indicates that a higher conidial density will often result in a faster control of the targeted insects. Consequently, where large insect pest populations exist, higher conidial concentrations are more effective to contain pest populations from incurring economic damages. However, low conidial concentrations can also be used in the initial developmental stages of pest populations to maintain them below economically damaging thresholds. [PERSON], et al. [58] and [PERSON], et al. [8] showed that the LT50 and LT90 values of _M. anisopliae_ and _B. basiana_ isolates applied to females of the European gypsy moth and of the Black timber bark beetle decreased by increasing conidial concentrations. [PERSON], et al. [59] used probit analysis to estimate the LT50 of _B. basiana_ at 10.45 days against _C. maculatus_ and _Sitophilus granarius_ (L.) (Coleoptera: Curculionidae). In our experiment, the survival time of larvae of _P. interpunctella_ and _T. granarium_ and of adults of _M. persicae_ depended on the dose of the fungi. In the case of _G.