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, 5 th instar nymphs were transferred to Paraguay tea seedlings, followed by spraying of conidial suspensions (1 × 10 9 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. Key words: Biological control, Ilex paraguariensis, rDNA-ITS ResumoA erva-mate (Ilex paraguariensis St. Hil.) é uma cultura nativa do Sul do Brasil, tendo grande importância socioeconômica também para o Paraguai e Argentina. Uma das principais pragas da cultura é a Gyropsylla spegazziniana (Hemiptera: Psyllidae), e pelo fato de não existirem inseticidas registrados para essa praga no Brasil, o uso de fungos entomopatogênicos pode ser uma alternativa para o seu controle. O objetivo desse trabalho foi caracterizar isolados dos fungos entomopatogênicos Beauveria spp., Metarhizium anisopliae, Isaria spp. e Lecanicillium spp. sobre G. spegazziniana. Para tal, ninfas de 5 o ínstar foram transferidas para mudas de erva-mate, seguido da pulverização das suspensões de conídios (1 × 10 9 conídios mL -1 ), e então as mudas foram acondicionadas em gaiolas de PVC (cloreto de polivinila), e mantidas em sala climatizada (26 ± 1°C; 12h00 de fotofase e U.R. 60 ± 10%). A mortalidade dos insetos foi avaliada diariamente, por 10 dias, e os isolados selecionados foram comparados entre si por meio do crescimento vegetativo, produção de conídios em meio sintético e em arroz, atividade inseticida e análises moleculares, utilizando-se o sequenciamento da região rDNA-ITS e marcadores RAPD. O gênero Beauveria spp. foi o mais eficiente, em especial o isolado Unioeste 44 que apresentou a maior mortalidade total s...

Caracterização morfofisiológica de fungos entomopatogênicos para o controle biológico de <i>Oncideres impluviata</i>

“…Martins (2014), caracterizando isolados de Beauveria bassiana, encontrou valores entre 0,2 a 26,2 x 10 8 conídios/colônia. Fomentini et al (2015) encontraram valores entre 2,2 e 3,2 cm para o diâmetro da colônia e produção de 0,1 a 13 x 10 7 conídios/colônia.…”

Using Sticky Card Traps to Evaluate Entomopathogen Fungi Occurrence in Insect Populations: A Cautionary Tale

“…The leaves of this plant also are used as a raw material for medicines and cosmetics (Cardozo & Morand 2016). Immatures of the psyllid, Gyropsylla spegazziniana Lizer & Treles (Hemiptera: Aphalaridae) cause galling (ampules) and disfiguration in the leaves of I. paraguariensis (Formentini et al 2015). For this reason, the psyllid's common name is 'ampolada-erva-mate' (yerba mate ampule).…”

“…(Hypocreales: Cordycipitaceae) (Alves et al 2013). Further screening identified a certain strain, B. bassiana (sensu lato) strain Unioeste 44, as being highly toxic to G. spegazziniana (Formentini et al 2015). Since then, efforts have focused on developing spore formulations and adjuvants to improve conidiospore performance and designing an "attract and infect" device (autodisseminator) to efficiently dispense the spores in yerba mate orchards (Loeblein 2019).…”

Bioassay Technique and Maintenance of Gyropsylla spegazziniana (Lizer, 1719) (Hemiptera: Psylloidea: Aphalaridae) in vitro Conditions

“…Descriptions of bioassay methods for ampule of yerba mate are scarce. There is one method for studying their biology (Leite & Zanol, 2001) and other where last-instar nymphs of the ampule were collected in a crop and transferred directly to yerba mate seedlings with a fine damp brush (Formentini et al, 2015(Formentini et al, , 2016.…”

“…The plastic containers used had numerous perforations at the bottom (approximately 1 mm in diameter) and a cross-shaped central opening in the lid ( Figure 1B). Twenty adults were transferred into each container, composing one replicate, and using five replicates per treatment, according to Formentini et al (2015). After that, 0.2 ml of 0.01% Tween solution in distilled water were sprayed onto the insects with an airbrush sprayer coupled to an air compressor (Figure 2A), with outlet pressure of 0.5 kgf/cm 2 .…”