Endophytic Development of the Entomopathogenic Fungus Beauveria bassiana Reduced the Development of Galls and Adult Emergence of Leptocybe invasa in Susceptible Eucalyptus

Abstract

Eucalyptus cultivation in arid regions is limited by the losses caused by the galling wasp, Leptocybe invasa Fisher and La Salle, 2004 (Hymenoptera: Eulophidae); it oviposits below the epidermis of the central veins, mainly on seedlings in nurseries and/or young plants in the field, causing galls where the insects develop. Galls modify the normal circulation of sap in vascular tissues, ultimately affecting the development of infested plants and resulting in slower growth. Eucalyptus genotypes tolerant to water stress are susceptible to L. invasa, and this pest has no effective control methods. Here, we aimed to (i) determine the initial infestation dynamics of L. invasa in Eucalyptus plants inoculated with Beauveria bassiana and (ii) identify any change in the development of galls. B. bassiana-inoculated seedlings were infested with L. invasa. Susceptible plants were unaffected, and gall development was negatively affected at multiple stages. A fungal solution containing B. bassiana reduced gall development and the emergence of L. invasa adults in eucalyptus plants at considerable rates. The total number of adult emergence holes was 89.74% fewer for inoculated plants when compared to uninoculated plants. These results can help develop B. bassiana products to control L. invasa in susceptible eucalyptus plants for improved, sustainable forestry.