Evaluation of Native Entomopathogenic Fungi for the Control of Fall Armyworm (Spodoptera frugiperda) in Thailand: A Sustainable Way for Eco-Friendly Agriculture

Abstract

Fall armyworm, Spodoptera frugiperda, entered Thailand in late 2018 and has now spread in several regions, with devastating effects in maize and rice production, which are some of the most important cereals in the world. Since then, farmers have utilized the available chemical insecticides to try to control it, but their efforts have been futile. Instead, they have ended up using extraordinary dosages, hence threatening non-target species and other fauna and flora, as well as being costly. In this regard, research has been ongoing, aiming to come up with eco-friendly solutions for this insect. We surveyed and collected various isolates of native entomopathogenic fungi intending to test their efficacy against fall armyworm. Six isolates of entomopathogenic fungi were obtained and identified to Beauveria bassiana based on morphological characteristics and multi-gene phylogenetic analyses. Thereafter, the six isolates of B. bassiana were used to perform efficacy experiments against fall armyworm. Additionally, the glycosyl transferase-like protein 1 (GAS1) gene was analyzed. Consequently, all the isolates showed efficacy against S. frugiperda, with isolate BCMU6 causing up to 91.67% mortality. Further, molecular analysis revealed that all the isolates possess the GAS1 gene, which contributed to their virulence against the insect. This is the first report of utilizing native entomopathogenic B. bassiana to manage S. frugiperda in Thailand, with the revelation of GAS1 as a factor in inducing virulence and cuticle penetration. This study has provided valuable information on the potential development of Beauveria bassiana as an eco-friendly bioinsecticide for the management of fall armyworm in Thailand.

Bioassays of Beauveria bassiana Isolates against the Fall Armyworm, Spodoptera frugiperda

“…Interestingly, one isolate of B. bassiana caused significant larval mortality against FAW [ 44 , 60 ]. Another study reported that the presently studied isolates of B. bassiana significantly affected the larval growth of Dendrolimus pini [ 90 ].…”

“…Using a hemocytometer, the conidial suspensions were adjusted to concentrations of 1 × 10 6 , 10 7 and 10 8 conidia/mL [ 59 ]. A dose-dependent mortality effect has already been observed in previous laboratory studies by many authors, so as such three doses were selected in the present study in order to investigate if there is any different observation between this study with multiple doses and previous studies that used multiple doses to assess the virulence of B. bassiana isolates against FAW [ 60 , 61 ].…”

“…The bioassays were laid out according to a completely randomized design with three replications for each treatment. Mycosis was assessed for the dead cadavers by following the approach of Aktuse et al [ 60 ]. The dead larvae were surface-sterilized with 70% alcohol and rinsed thrice in distilled water.…”

“…Entomopathogenic fungi can strengthen Integrated Pest Management (IPM) programs and reduce the environmental impact of pesticides against S. frugiperda in Mexico [ 58 , 59 ]. The isolates of B. bassiana proved to be effective for the management of S. frugiperda in Thailand [ 60 ]. B. bassiana isolates are considered to be a sound biocontrol agent for the management of FAW [ 61 , 62 ].…”

Lethal, Sub-Lethal and Trans-Generational Effects of Chlorantraniliprole on Biological Parameters, Demographic Traits, and Fitness Costs of Spodoptera frugiperda (Lepidoptera: Noctuidae)

“…Similarly, the baseline susceptibilities of different insecticides with control failure estimation for S. frugiperda were determined in Burkina Faso [ 15 ]. Entomopathogenic nematodes were used to control S. frugiperda in Thailand [ 16 ]. Insecticide ‘ampligo’ was used against S. frugiperda in the coastal Savannah agroecological zone of Ghana [ 17 ].…”