Colonzation of Tobacco Plants by Fungal Entomopathogens and the Effect on Consumption over Diabrotica speciosa (Coleoptera: Chrysomelidae)

Abstract

Entomopathogenic fungi are naturally occurring microorganisms that attack insect pests,making them exceptional allies when developing biocontrol strategies. A particular aspect of theecology of these fungi is that they interact not only with insects but also with plants, being able tocolonize them endophytically without causing symptoms of disease. The objectives of this studywere to determine the endophytic capacity of different species of entomopathogenic fungi in tobacco plants by means of foliar spraying, to evaluate the persistence in planta of the entomopathogens and the effect of endophytes on consumption by coleopteran pests. A total of 24 strains were analyzed to test endophytic capacity at 7, 14, 21 and 28 days post inoculation. A significant effect of the strains was found. On days 7, 14 and 21, the strain that showed the highest colonization percentages was B. bassiana LPSc 1215, and at day 28 B. bassiana strains LPSc 1215 and LPSc 1212 exhibited the best endophytic capacity, maintaining elevated colonization percentages. Choice test results indicated that D. speciosa fed indiscriminately on colonized and non-colonized leaves. The results indicate that B. bassiana LPSc 1215 constitutes a strain that would merit further investigation for the purpose of pest management in tobacco cultivation.