Characterization of the Entomopathogenic Bacteria of the Fall Armyworm (Spodoptera frugiperda J.E. Smith,) in Western Burkina Faso

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Résumé

Utilizing entomopathogenic microorganisms as a means of management is a compelling technique to control Spodoptera frugiperda. This polyphagous insect poses a significant threat to maize growing given the limits of chemical pesticides control. Surveys were carried out in maize fields to collect dead larvae, live larvae and chrysalids of Spodotera frugiperda. Dead larvae were utilized to isolate bacteria, whereas live larvae were cultivated in order to carry out pathogenicity assessments of the isolated bacteria. The pathogenicity tests involved introducing the bacterial strains into the larvae's diet, which consisted of maize leaves, to observe and evaluate the larvae's growth and developmental stages across different phases. A total of 240 live and 10 dead larvae were collected from maize fields, and 259 strains were isolated. Comparative analysis of the 24 representative strains, 16 gram-positive and 8 gram-negative, revealed that gram-positive strain 5 and gram-negative strain 20 induced 100% and 56% mortality, respectively, in the larvicidal test. Gram-positive strains 1, 4, 5, 6, 11, 13, and 15 and gram-negative strains 18, 19, 23, and 24 completely inhibited the laying of eggs. In addition, gram-positive strains 5 and 11 produced 100% and 90% rate of organic essences that are out of harm’s way insect limits. For gram-negative strains 18 and 20, these rates were 80% and 88% respectively. Thus, gram-positive strains 5, 11, and 20 and gram-negative strains 18 and 20 can be considered entomopathogenic bacteria of Spodoptera frugiperda. In addition, it is important to carry out molecular identification of these strains to facilitate testing under real-life conditions.

Mots-clés

Entomopathogenic bacteria, Spodoptera frugiperda, Pathogenicity, Characterization, Biological control, Burkina Faso