## 4 Discussion  
Biocontrol agents represent an alternative to chemical pesticides. They become natural enemies attacking pests, without affecting humans or animals. Entomopathogenic fungi are particularly important because of their pathogenicity routes, a variety of hosts, and their potential to control a wide range of pests. In this study, we observed that conidia viability and germination were not affected after analyzing conidia viability in response to formulation ingredients. Some advantages of using oily formulations include the increase in the resistance to thermal changes, after evaluating different vegetable oils formulations, using the entomopathogenic fungus _Metrahizium robertsii_ ([PERSON] (1883), formerly known as _M. anisopliae_ ([PERSON], 1980). It has been reported that the use of oils in formulations favors spores' survival by maintaining their humidity ([PERSON], 1983). However, we observed a delayed effect on _Hirstella ctitiformis_ mycelial growth in the presence of the maize-based liquid vegetable oil. The typical composition of corn oil is 11% palmitic, 2% stearic, 24.1% oleic, 61.9% linoleic, 0.7% linoleic, and to a lesser extent, other fatty acids (< 1%) ([PERSON], 1983). A high concentration (3.9 mmol/L) of palmitic acid was shown to inhibit mycelial growth of fungi such as _Alternaria solani_ ([PERSON], _Colletotrichum lagenarium_ ([PERSON].) [PERSON] and _Fusarium oxysporum_ [PERSON] emend. [PERSON] & [PERSON]. Similarly, linoleic acid (2 mmol/L) was reported to reduce mycelium growth but oleic acid (3.2 mmol/L) did not inhibit mycelial growth of these fungi ([PERSON], 1983). To date, studies on fatty acids antifungal mechanisms have focused on the inhibitory effect against human pathogenic fungi, whereas antifungal activities against entomopathogenic fungi are still unknown. Therefore, it can be inferred that fatty acids present in corn-based vegetable oils may interfere with _Hirstella ctitiformis_ mycelial growth. Regarding conidia viability results, we showed that gums used in formulations at high concentrations reduced conidia viability at the two temperatures evaluated, in shelf life experiments. Number of viable conidia was initially calculated, inoculating a suspension of 1 cm\({}^{2}\) agar squares in Petri dishes. Conidia were incubated and the germination percentage was determined at least three times, thus assuring that conidia in the control were as viable as in all treatments. Nevertheless, each treatment was independently inoculated in Petri dishes. This may explain why the initial germination is different among treatments. The formulation process may lead to an initial loss of viability, which is one of the disadvantages of using _Hirstella_ as a biological control agent, in addition to its slow growth and short lifetime ([PERSON], 1983). This was shown in the germination at time 0 for both strains, where the germination percentage of the conidia was between 90.29% and 94.29% among treatments (Table 3). It was also observed that conidia germination in the untreated control was lower (viability between 91.8% and 93.7%), as compared with that of formulated treatments (Tables 4-7). However, by comparing this value with the initial assay, we did not observe significant differences. It is possible that formulation ingredients maintained conidia viability by protecting the muclaginous layer that covers conidia, preventing their early germination in a nutrient-deficient medium (distilled water) ([PERSON], 1983). This protective effect was observed with the addition of the vegetable oil in powder. After testing _Trichoderma asperellum_ [PERSON], Lieck & Nirenberg formulations at higher storage temperatures than those used in our study, it was observed that supersaturation of adherents on conidia completely inhibited their viability ([PERSON], 1983).