Isolation of Native Strains of Entomopathogenic Fungi from Agricultural Soils of Northeastern Mexico and their Virulence on Spodoptera exigua (Lepidoptera: Noctuidae)

Abstract

Spodoptera exigua Hübner (Lepidoptera: Noctuidae) is considered a polyphagous pest distributed worldwide with a wide range of hosts, and is also considered a serious plague for vegetables and ornamentals. The objective of this study was to explore the occurrence of entomopathogenic fungi in agricultural soils from Mexico and to evaluate its virulence and effect on the life cycle of S. exigua. Selected isolates (HEB1 and 01) were used to perform toxicity bioassays on neonatal larvae of S. exigua; additionally, the GHA (Beauveria bassiana), Pfr-612 (Cordyceps fumosorosea), Ma, and 2 isolates HIB-11 and HIB-12 (Metarhizium anisopliae) were included to obtain the median lethal concentration (LC 50 ) and the median lethal time (LT 50 ). Also, the life cycle of the surviving individuals was followed up after treatment to document the effects of the entomopathogenic fungi application. The isolates belong to 2 different species, which are Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) and Cordyceps fumosorosea (Wize) Kepler, B. Shrestha & Spatafora (Hypocreales: Cordycipitaceae) (formerly Isaria fumosorosea). In toxicity tests, the isolate HIB-12 of Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Cordycipitaceae) showed better mortality results against S. exigua than the other fungi evaluated with LC 50 of 3.17 × 10 6 conidia per mL. The lethal time of LT 50 oscillated between 3 to 5 d and the HIB-12 isolate had the lowest lethal time (3.15 d). During the monitoring of the biological cycle after treatment, the greatest interruption of the metamorphosis was caused by the GHA strain, while the Ma strain was the one that induced the slightest interruption of the biological cycle. These results show the feasibility of using strains of M. anisopliae for control of larval stages of S. exigua and their possible formulation for agricultural use, as well as opening a way for the exploration and research of mechanisms or metabolites involved in the interruption of metamorphosis due to the application of entomopathogenic fungi, specifically B. bassiana.

Biological control of Spodoptera frugiperda J.E. Smith and Schistocerca piceifrons piceifrons Walker using entomopathogenic fungi

“…I. fumosorosea is widely used to control Hemiptera; however, several authors have pointed out the high efficiency of this species for the control of S. frugiperda, Spodoptera littoralis Boisduval, and Spodoptera exigua Hübner (Altinok et al, 2019;Gandarilla-Pacheco et al, 2021). Therefore, it can be a biological alternative for the control of this type of pests.…”

“…Vuill) to control the Central America locust (Brunner-Mendoza et al, 2019;Barrientos-Lozano et al, 2021). Altinok et al (2019) and Gandarilla-Pacheco et al (2021) have reported that Isaria fumosorosea (Wize) Kepler, B. Shrestha & Spatafora is efficient to control Lepidoptera. This species can cause a 29-100% mortality among S. frugiperda and S. litura Fabricius larvae (Lei et al, 2020;Ullah et al, 2022a).…”

Isolation and Identification of Entomopathogenic Fungi from Soils of Manipur (N-E India)

“…The PCR mixture (30 µl) consisted of 15 µl of universal master mix, 12 µl of molecular water, 1 µl of primers ITS1 and ITS4 each and 1 µl of extracted DNA. PCR amplification was carried out with specific temperatures, described by Gandarilla-Pacheco et al (2021). After amplification, the PCR products were run on 1% Agarose gel with Ethidium bromide and then bands were visualized under UV light using a Gel documentation unit.…”