In the last decades, the use of entomopathogenic fungi for the control of pest insects has increased globally, however a key step to achieve the successful application of fungal propagules as biocontrol agents depends of various factors, inoculum production being one of the essential stages for these microorganisms to be used in pest management programs. The objective of this study was to evaluate the production of conidia by solid fermentation and biphasic culture in different sporulation matrices for four native isolates and a strain of Isaria fumosorosea that have been shown potential for the control of various insects at the laboratory level. The experimental design was completely randomized, two propagation methods were used with six treatments and ten repetitions per treatment; the data were analyzed using an analysis of variance and the means were compared using the Tukey test (p≤ 0.05). In the production by solid fermentation the minimum value of 5.30 × 10 5 conidia g -1 was registered with the pericarp of peanut and the maximum of 2.35 × 10 7 conidia g -1 in the corn grain; in the biphasic culture the minimum of 7.60 × 10 5 conidia g -1 was observed in birdseed and the maximum of 2.07 × 10 7 conidia g -1 in rice. The differences were significant (p ≤ 0.05) in the production by method and by substrate, in solid fermentation 6.84 × 10 6 conidia g -1 and in biphasic culture 8.85 × 10 6 conidia g -1 . In the production by substrate, the rice showed 1.75 × 10 7 conidia g -1 and the lesser canary seed concentration (7.80 × 10 5 conidia g -1 ). The average production per isolate and / or strain was of the order of 10 6 and significant difference was registered (p ≤ 0.05) among the fungi, the isolate HIB-9 showed concentration in average higher in the production (7.90 × 10 6 conidia g -1 ) and the isolated HIB-19 was the least effective, with only 1.08 × 10 6 conidia g -1 . The results obtained show marked differences between the isolates with respect to their capacity to use the different substrates used as propagation media to obtain conidia of I. fumosorosea.
<p><strong>Background.</strong> The formulation of agents of biological origin with insecticidal activity is one of the most effective methods for the control of lepidopteran pests due to their feeding forms. The insecticidal activity of <em>B. thuringensis</em> is widely known, which is why it is believed that native strains of this bacillus could have toxic activity on larvae of the cobweb worm, <em>H. cunea</em>. <strong>Objective.</strong> To prepare by means of the spray drying technique microencapsulated formulations of a native strain of <em>B. thuringensis</em> with toxic activity on <em>H. cunea</em>. <strong>Methodology.</strong> The experimental design was completely randomized and the means were compared with the Tukey test (p ≤ 0.05). The strain selected for the formulation is a key Mexican strain GM-10 belonging to the aizawai variety and presented an LC<sub>50</sub> of 0.007 ng cm<sup>-2</sup> in artificial diet, and a LT<sub>50</sub> of 80.83 h. To prepare the formulations, a phago-stimulant was first selected by means of food preference tests with powdered leaves of walnut, blackberry, ash, loquat and walnut shell powder and a commercial phage-stimulant (Coax<sup>®</sup>), and ash was selected with 61.4% of the larvae attracted. Once the phagostimulant was selected, encapsulated formulations were developed with a mixture of polymers (Capsul<sup>®</sup>-bovine gelatin), as a base. Several formulations were then made to select an adhesion additive, and the ingredients tested were guar gum, core<sup>®</sup> gum and xanthan gum. <strong>Results.</strong> Food preference bioassays to establish the affinity of <em>H. cunea</em> for some of the formulations showed that the larvae had a similar affinity for feeding on all formulations (p ≥ 0.05), while in the trials to select an adherent for the formulation xanthan gum presented the best adherence (p ≤ 0.05). <strong>Implications.</strong> The evaluated formulations preserved their toxic activity after microencapsulation with an LC<sub>50</sub> of less than 0.05 ng cm<sup>-2</sup> of <em>B. thuringensis</em>. <strong>Conclusion. </strong>These results show the feasibility of using the spray drying method to obtain an effective formulation for the treatment of the immature stages of <em>H. cunea</em>.</p>
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