Bermudagrass plants endophytically colonized with Metarhizium anisopliae isolates reduces the biological performance of fall armyworm

Abstract

The knowledge of the interactions between endophytic entomopathogenic fungi and forage plants and their influence on Spodoptera frugiperda, an emerging pest of pastoral systems, is important to elucidate the multifunctionality of these microorganisms and their benefits to agroecosystems. This study investigated the influence of endophytic colonization with different isolates of Metarhizium anisopliae on Cynodon dactylon (L.) Pers (Poaceae) cv. Tifton 85 on biological and behavioral aspects of S. frugiperda. The application of a suspension of isolates (1 × 10⁸ conidia ml⁻¹) to the base (soil drench) of C. dactylon seedlings was effective to promote endophytic colonization. Spodoptera frugiperda caterpillars fed throughout their larval stage with leaves of plants colonized endophytically by the three isolates studied (CEPAF_ENT 25, CEPAF_ENT 27, and IBCB 425) of M. anisopliae showed considerable reduction in their biological performance, especially in parameters of their fertility life table. However, the tested isolates did not show pronounced effects on feeding and oviposition preference, although there was a trend of preference of caterpillars and moths for colonized plants, especially in no-choice tests. Thus, applications of mycoinsecticides based on M. anisopliae for the management of the spittlebug complex (its main use currently) may lead to the endophytic colonization of C. dactylon cv. Tifton 85 and influence S. frugiperda population density as well as the impact this pest causes to pastures. The isolates used in this study exhibit multiple spectrums of action and potential to produce new biological products for the market.