Characterization and activity of entomopathogenic fungi isolates against “paraguay tea ampul” (Gyropsylla spegazziniana) (Lizer & Trelles) (Hemiptera: Psyllidae)

Abstract

Paraguay tea is a native crop of southern Brazil and is also socioeconomically important in Paraguay and Argentina. One of the main pests of this crop is Gyropsylla spegazziniana (Hemiptera: Psyllidae). As there are no registered insecticides for this pest in Brazil, the use of entomopathogenic fungi is an alternative method for its control. This study aimed to evaluate and characterize isolates of the entomopathogenic fungi Beauveria spp., Metarhizium anisopliae, Isaria spp. and Lecanicillium spp. on G. spegazziniana. For this purpose, 5th instar nymphs were transferred to Paraguay tea seedlings, followed by spraying of conidial suspensions (1 × 109 conidia mL-1) and then placing the seedlings in polyvinyl chloride (PVC) cages and maintaining them in a temperature-controlled room (26 ± 1°C, 12h00 photophase, 60 ± 10% R.H.). Insect mortality was evaluated daily for 10 days, and the selected isolates were characterized according to their vegetative growth, conidial production in synthetic culture medium and rice and insecticidal activity as well as through molecular analyses, including sequencing the rDNA-ITS region and RAPD analysis. The genus Beauveria spp. was the most efficient, particularly the Unioeste 44 isolate, which caused the greatest total mortality of G. spegazziniana (81.7%) and showed among the highest conidial production levels on rice, indicating a significant potential to be used in an integrated management program for this pest. Molecular analysis of the rDNA-ITS region allowed the isolates to be identified as B. bassiana and B. brongniartii, and RAPD markers were found to be associated with virulence.