Sustainable control of Dalbulus maidis: A field study with entomopathogenic fungi

Abstract

Since its first report in Brazil in 1938, Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae) has been considered a secondary pest for maize. However, this insect has now become a key corn pest and the main phytosanitary threat to production in Brazil due to its potential to transmit pathogens. This study investigates sustainable tactics for managing the corn leafhopper in an integrated field approach. We evaluated the potential synergistic effects between formulations based on entomopathogenic fungi and corn hybrids with varying resistance levels to maize stunt complex. Along with assessing the incidence and severity of diseases, we evaluated the corn leafhopper's infestation in symptomatic and asymptomatic plants and the correlation with the symptoms caused by the disease at various plant development stages. We studied the following management practices, comprising applications of (i) Beauveria bassiana Balsamo (Hypocreales); (ii) B. bassiana + Cordyceps fumosorosea Wize (Hypocreales); (iii) C. fumosorosea; (iv) Metarhizium anisopliae Metschnikoff (Hypocreales); (v) M. anisopliae + B. bassiana; (vi) chemical control (methomyl—positive control). Dalbulus maidis preferentially infested the low-resistance hybrid, and this hybrid plant also showed higher disease symptom scores. There was a significant interaction between control timing and pathogen incidence; this correlation occurred up to the V6 phenological stage. The combined management of M. anisopliae + B. bassiana and M. anisopliae (alone) resulted in a reduction in D. maidis infestation. We found lower disease scores when these treatments were applied. Our results showed that combining resistant hybrids with entomopathogens results in more productive harvests.