## 1 Introduction  
Numerous setbacks, including pollution, toxicity to animals and plants, and rampant insecticide resistance, are associated with the use of synthetic insecticides [1], and these have led to increased solicitation for alternative solutions to insect infestation problems on crops. Knowledge gained over the years on the influence of endophytic microbial symbionts on plant defense mechanisms vis-a-vis insect herbivory have opened up opportunities for management of insect pests using fungal endophytes.  
Endophytic fungi occur ubiquitously in plants and colonize them without adverse effects; meanwhile, plants serve as host and provide nutrient to these fungi. Through this mutualistic relationship with their plant hosts, endophytes enhance plants' tolerance to biotic and abiotic stresses [2]. Endophytic fungi have also been reported to induce increased growth in plants, such as grasses and strawberry [3; 4]. The growth enhancing effect can be attributed to the ability of fungi to mobilize valuable nutrients for plant growth; for example, _Metarhizium robertsii_ (Hypocreales) promotes root growth and nitrogen absorption in switchgrass and haricot bean [5]. A study by [PERSON] et al. [3] demonstrated improved plant health coupled with an increase in shoot-root ratio for plants treated with the fungus _B. bassiana_. _M. robertsii_ and _B. bassiana_, two well-known entomopathogenic fungal species, have strains that can cause natural epizootic deaths in many insects [6]. Plant growth and productivity, as well as defense, could be enhanced by exploring the plant-fungus interaction.  
There are evidences in literature to prove that endophytic fungi can curb insect infestations on plants. For example, western tarnished plant bugs (_Lysus hesperus_) and southern green stink bugs (_Nezara viridula_) showed strong negative responses to flower buds (_L. hesperus_) and fruits (_N. viridula_) from plants that had been colonized by endophytic fungi compared to control plants [7]. A strain of the endophytic fungus _B. bassiana_ reduced infestation rates and growth of _P. ficus_ on potted grapevine plants [8]. Interesting findings, such as the aforementioned, have spurred researchers to study further the mechanisms through which fungal endophytes influence insect herbivory. Surely, this knowledge will improve our understanding and exploitation of the fungus-plant-insect relationship for sustainable pest management.  
Some endophytic fungi have been reported to produce metabolites that can reduce insect infestations on their host plants [9]. It is believed that increased in quantity and diversity of secondary metabolites in endophyte-containing plants is somewhat responsible for the reduction of insect herbivory on plants [10]. In a study carried out by [PERSON] et al. [11], _Acemonium strictum_ systemically influenced the host selection of _Helicoverpa armigera_ moths for oviposition, possibly through changes in volatile emissions and some unknown biochemical parameters. Fungal endophytes can increase the production of antioxidant in plants, as well as produce antioxidant compounds, such as phenolics. They also produce plant growth hormones and enhance plant nutrient absorption, favoring increased germination success and growth rate [12; 13].  
The grapevine mealybug (_Planococcus ficus_ [Homoptera]) is a sap-sucking insect that is difficult to control [14; 15]; individuals of this species often hide in plant crevices and have a protective waxy layer. It is among the most serious pests of vineyards, causing substantial losses globally [16; 17]. The systemic colonization of tissues of young plants with endophytic _B. bassiana_ can lead to sustainable control of _P. ficus_. The objectives of this study were to assess the effect of _B. bassiana_ inoculation of grape plants on (i) the infestation level of _P. ficus_ and (ii) growth and chemical constituents of potted grapevines.