# Could _Gnomoniopsis castaneae_ Be Used as a Biological Control Agent against Insect Pests?
## 1 Introduction  
Entomopathogenic fungi (EPF) make up a specialized group of fungi which comprise numerous genotypes [1]. Within the framework of the biocontrol of insect pests in field crops and storage facilities, EPF fungi have attracted extensive interest in recent years [2], EPFs inhabit a wide range of dwellings including urban environments, meadow land, dry, and agricultural places. They demonstrate high virulence against many insects and have minimal residual effects.  
Inset pathogens have a biological cycle that is synchronized with that of the host but also adapted to the prevailing environmental conditions [3]. Infection can be restricted by low levels of relative humidity, shortage of nutrients in the cuticle, as well as the inability to recognize the host due to the absence of contributing factors [4, 5]. The degree of the infection depends on the infectivity of the fungus, the defensive resilience of the insect, and several other biological and abiotic factors [3]. In the 1990s, _Isaria funosrosae_ Wize(Hypocreales: Clavicipitaceae) was reported as the most common entomopathogenic fungus in Asia, Russia, the USA, South America, and India, infecting _Bemisia_ spp. (Hemiptera: Sternorhyncha) and _Trialeurodes vapourarium_ (Hemiptera: Sternorhyncha) [6]. Depending on the strain, _I. fumosorosea_ has a wide range of hosts and could be effective against several insect pests [7; 8; 9; 10]. For example, it has been proved highly effective against _Plutella xylostella_ L. (Lepidoptera: Plutellidae) [11; 12; 13]. In addition, it has been commercially available all over the world [14].  
On the other hand, _Gnomoniopsis castaneae_ G. Tamietti (Sordariomycetes: Gnomoniaceae) has been recognized as the cause of the chestnut brown rot in Europe and Australasia [15; 16; 17; 18]. The chestnut brown rot which has appeared in several chestnut areas around the world, could be the most threatening disease of chestnuts, causing losses to post-harvest yields as high as 60-70% [19]. Additionally, _G. castaneae_ causes chestnut canker symptoms in several countries worldwide [20; 21]. While its origin has not been definitively established yet, _G. castaneae_ is a cryptic species which has been reported in Australasia and India on Japanese (_Castanea crenata_ Sieb. [PERSON]. (Angiosperms: Fagales) and European (_C. sativa_ Mill.) chestnut.  
_G. castaneae_ exists endophystically in most chestnut organs and tissues, in an asymptomatic manner unless favorable environmental conditions trigger its emergence [22; 23]. For instance, the chestnut brown rot is aggravated by rainfall during flowering [24], most probably because flowers are infected by ascospores dispersed from dead burrs in the orchard [18]. In Italy and Switzerland, a noteworthy aggravation of chestnut brown rot took place after the invasion of the _Dryocosmus kuripililus_ [PERSON] (Hymenoptera: Cynipidae) chestnut gall wasp in the mid-2000s [25; 26]. However, after studying the dead _D. kuripililus_ galls, [PERSON], et al. [27] reported that the galls and the associated leaves had in fact been killed by _G. castaneae_ before the adults flew in. Upon this basis, the question arises as to whether _G. castaneae_ could serve as a natural agent for the control of the chestnut gall wasp and other insect pests [28]. Apart from its profound phytopathogenic behavior, field observations and lab bioassays have demonstrated the possibility for _G. castaneae_ to act also as an entomopathogenic fungus against chestnut pests, such as the chestnut gall wasp [27; 28; 29; 30; 31].  
For this study, we recorded the survival of three major pests, the Indian Meal Moth _Plodia interpunctella_ [PERSON] (Lepidoptera, Pyralidae), the Khapra beetle _Trogoderma granarium_ [PERSON] (Coleoptera, Dermestidae), and the Green Peach Aphid _Myzus Persicae_ [PERSON] (Hemiptera, Aphididae). The present study was designed to investigate the potential of _G. castaneae_ as a biocontrol agent in comparison to a common EPF species, _I. fumosorosea._