The objective of the present work was to develop a method for the preservation of T. harzianum conidia at room temperature and the immobilised conidia propagation in submerged culture. This was accomplished by immobilising the strain in sodium alginate capsules (white capsules) and subsequently propagating them in a column bubble reactor (green capsules). Three capsule diameters were tested (micro, medium and large capsules), which were produced by emulsion internal gelation and dripping methods. Tested variables were the immobilised conidia propagation in submerged culture for free conidia production, the immobilised conidia viability throughout the time (two years), the resistance of the encapsulated conidia to the UV irradiation of short and long wavelength, and the antagonistic effect of the encapsulated T. harzianum against four phytopathogenic fungi. It was found that the medium capsules (1.5 ± 0.3 mm) favoured the massive production of released conidia in submerged culture and that the higher the density of conidia per capsule, the greater the protection against the ultraviolet irradiation. Regarding the conidia preservation in calcium alginate, a viability loss of around 30% was observed two years after storage at environmental temperature in both white and green capsules; along the two years that the viability of conidia was analyzed, the purity of the formulation was corroborated. The results presented here show the efficacy of the green and white capsules for T. harzianum preservation at room temperature for a long period of time.

Cedrela odorata L. is a plant species from the Meliaceae family that is cultivated for timber production. Although the C. odorata essential oil (EO) contains mainly sesquiterpenes, its insecticidal potential is unknown. The lipophilic properties and high degradation capacity of EOs have limited their application for use in pest control. However, the currently available knowledge on the nanoemulsification of EOs, in addition to the possibility of improving their dispersion, would allow them to prolong their permanence in the field. The objective of the present work was to develop a nanoemulsion of the C. odorata EO and to evaluate its larvicidal activity against Spodoptera frugiperda. The EO was obtained by the hydrodistillation of C. odorata dehydrated leaves, and the nanoemulsion was prepared with non-ionic surfactants (Tween 80 and Span 80) using a combined method of agitation and dispersion with ultrasound. The stability of the nanoemulsion with a droplet diameter of <200 nm was verified in samples stored at 5 °C and 25 °C for 90 days. Both the C. odorata EO and its corresponding nanoemulsion presented lethal properties against S. frugiperda. The results obtained provide guidelines for the use of wood waste to produce sustainable and effective insecticides in the fight against S. frugiperda. In addition, considering that a phytochemical complex mixture allows the simultaneous activation of different action mechanisms, the development of resistance in insects is slower.

Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) is a polyphagous insect pest native to America. Due to its capacity for adaptation and migration, it is currently located in Africa, Asia, and Oceania, where it threatens agricultural crops. The ability of S. frugiperda to develop resistance to insecticides is one of the reasons for the continuous search for more effective, low-cost, and environmentally friendly control products. In the present work, the insecticidal activity of ethanolic and hexane extracts obtained from fresh and dehydrated leaves of Piper auritum Kunth (Piperales: Piperaceae), Piper umbellatum L. (Piperales: Piperaceae), and Cedrela odorata L. (Sapindales: Meliaceae) was studied against first instar larvae of S. frugiperda. The ethanolic extracts of the dehydrated leaves of C. odorata and P. auritum presented insecticidal activity as high (100% mortality at a concentration of 92 mg/cm²) as that obtained with the positive control, Melia azedarach L. (Sapindales: Meliaceae). The GC-MS analysis of the extracts revealed the presence of phytochemicals classified mainly into the groups of monoterpenes, sesquiterpenes, diterpenes, phenylpropanoids, alcohols, and fatty acids. P. auritum grows and propagates rapidly. In addition, due to its low toxicity in mammals and non-target insects, it is a plant with the potential to be used as a botanical insecticide. The exposure of S. frugiperda larvae to low concentrations of ethanolic extract of P. auritum allowed us to observe their biological activity in the development of this insect. The LC₅₀ was 22.1 mg/cm². At sublethal concentrations (LC₂₁ and LC₃₅) the low fertility of the emerging adults was noticeable.