## 1 Introduction  
Chemical pesticides currently account for 95% of the global pesticide market and prevent about 50% of crop losses, which have not decreased in the last decades. Reports of the undesirable effects of chemical pesticides on animal and human health have prompted the search for alternatives to chemical pesticides [1, 2].  
Biological control of insect pests reduces harmful chemicals and pests-associated crop yield loss by using beneficial organisms, including insects, plants, or microorganisms. One of the most relevant biological control strategies under development are biopesticides, involving formulations based on entomopathogenic bacteria, fungi, or viruses [3, 4].  
Entomopathogenic fungi are commonly used as biopesticides to control aphids, ticks, and other insect plague populations, affecting plants and animals [5]. Their application is in the form of conidia, which are commonly combined with other inert materials for protection from environmental changes and stabilization during storage [6]. Some polymers used as adherents in formulations have a dual purpose. For example, arabic gum (_Acacia_ gum) is used as an emulsifier for safer and effective bioactive components delivery after an application [7] and to encapsulate entomopathogenic fungi [8]. It has also been reported that _Hirstuella_ produces a protective exopolysaccharide against desiccation [9, 10].  
Among entomopathogenic fungi, _Hirstella_ is one of the most abundant and important fungal genera for pest insect control in the field. It includes about 90 species infecting and parasitizing a wide variety of invertebrates such as mites and insects, many of which are considered pests of economic importance [11]. In this regard, _Hirstella citriformis_. [PERSON] is the only entomopathogenic fungus involved in _Diaphorina citri_ Kuwayama natural epizootics, allowing for its dissemination [12; 13; 14]. _H. citriformis_ has been isolated from _Diaphorina citri_ carcasses in Mexican citrus localities [15; 16; 17], which has allowed for the identification of several strains of interest, as possible biocontrol agents [18]. It is a difficult-to-grow, complex fungus with a limited shelf life and well-known biological control potential against _Diaphorina citri_, which develops a low spore amount compared with other entomopathogenic fungi [19].  
_H. citriformis_ has been applied to control _Diaphorina citri_ Kuwayama and _Bactericera cockerelli_ Sulc. [13; 15], which are _Candidatus_ Liberbacter spp. bacterium vectors. This bacterium is associated with several diseases in tomato, chili, and potato and is the causing agent of the Huanglongbing disease (HLB) [18; 20]. The main control method against _D. citri_ and _B. cockerelli_ is based on chemical insecticides. However, when the resistance of an insect pest to insecticides increases, the insecticide becomes ineffective and may also confer cross-resistance to other related chemical compounds [21; 22]. For the biocontrol of such insects, high-efficacy formulations are based on entomopathogenic fungi, such as _Metarhizium robertsii_ (formerly known as _Metarhizium anisopliae_) ([PERSON]) [PERSON] (1883), _Isaria funosoroseus_ [PERSON], and _Beauveria bussiana_ ([PERSON] -Criv.) [PERSON]. [23; 24]. The aim of the present study was to increase _H. citriformis_ conidial viability, using formulations containing _Acacia_ and _H. citriformis_ gums as inert materials to improve the formulated conidia shelf life and support their stability for at least three months.