Antagonist Action of Endophytic Metarhizium anisopliae Isolates on Development, Reproduction, and Host Selection of Grass Bug in Bermudagrass.

Abstract

To understand the interactions of entomopathogenic fungi with forage plants and their influence on associated herbivorous, we evaluated the influence of endophytic colonization with three isolates (CEPAF_ENT 25, CEPAF_ENT 27, and IBCB 425) of Metarhizium anisopliae on Cynodon dactylon, regarding the biological and behavioral aspects of Collaria scenica, an emerging sucking pest in pastoral systems in Brazil. The application of suspensions at the base of plant (drench) was effective in promoting endophytic colonization, especially in the roots, with emphasis on isolates CEPAF_ENT25 and CEPAF_ENT27. Despite the significant reduction in damage caused by C. scenica observed in plants colonized with isolate CEPAF_ENT 27 in a choice test, our results indicated a limited influence of the isolates tested on the host selection behavior and in C. scenica development, including parameters of the fertility life table. The cluster analysis, however, indicated a significant difference between all isolates tested in terms of the chemical-bromatological composition and the levels of photosynthetic pigments in inoculated plants. The biplot analysis indicated that isolate CEPAF-ENT27 (most promising) showed a positive correlation with nitrogen, potassium, calcium, boron, copper, and zinc levels, as well as with chlorophyll a and b levels. Additionally, foliar magnesium levels were significantly higher in all isolates tested. Improvements in plant nutrition may increase tolerance in infested plants through compensation mechanisms, contributing to more resilient pastoral systems.