Abstract
The control of Spodoptera frugiperda is based on synthetic insecticides, so some alternatives are the use of entomopathogenic fungi (EF) and neem extract. The objective of the study was to evaluate in vitro effectiveness of native EF and neem extracts on S. frugiperda larvae. Six EF were identified by DNA sequencing of ITS regions from three EF (Fusarium solani, Metarrhizium robertsii, Nigrospora spherica and Penicillium citrinum). They were evaluated in concentrations of 1 × 10⁸ spores/ mL. In addition, a second bioassay was carried out evaluating only F. solani, M. robertsii and N. sphaerica and the addition of vegetable oil. On the other hand, extraction of secondary metabolites from neem seed (Azadirachta indica) was carried out by performing, mass (g) and solvent volume (mL ethanol and water) combinations, which were subjected to microwaves and ultrasound. Subsequently, these extracts were evaluated in concentrations of 3%, 4% and 5%. A survival analysis was performed for each of the bioassays. With respect to the results of the first bioassay, F. solani obtained a probability of survival of 0.476 on the seventh day, while in the second bioassay, M. robertsii obtained 0.488 survival probability. This suggests that the expected percentage of larvae that stay alive on the sixth day is 48.8%. However, in the evaluation of the neem extract the combination 1:12/70% to 4% caused 84% mortality of larvae. The use of native HE and neem extracts has potential for the control of S. frugiperda.
Highlights
IntroductionSpodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) commonly called the armyworm is an important pest in many crops such as sorghum, rice, cotton and alfalfa (Nexticapan-Garcéz et al, 2009)
Isolation of entomopathogenic fungi In this step, 20 grams of soil were placed on Petri dish with two larvae of Tenebrio sp. which were used as a trap insect to obtain EF
The molecular identification determined that A1, P3 and P4 belonged to Fusarium solani
Summary
Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) commonly called the armyworm is an important pest in many crops such as sorghum, rice, cotton and alfalfa (Nexticapan-Garcéz et al, 2009). Around 750 species of EF have been reported affecting pests of economic importance, among them some genres as, Metarhizium, Beauveria, Isaria, Verticillium and Fusarium isolates (Motta-Delgado and Murcia-Ordoñez, 2011). For its use, it is necessary the correctly identify EF, since traditionally, it is done by morphological characters (Allende et al, 2013). The identification by morphological characters can be complemented with other
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