Virulence of entomopathogenic nematodes and their symbiotic bacteria, under laboratory conditions, aiming controlling Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Pseudococcidae) on sugarcane.

G G Monteiro,H H Paulo,L M Lacerda,G Pelegrini,R A Polanczyk,J Chacon-Orozco,D D Nascimento,L G Leite

doi:10.1590/1519-6984.253780

Abstract

Sugarcane crops Saccharum spp. (Poales: Poaceae) produces different derivatives to the world: sugar, ethanol and bioenergy. Despite the application of pesticides, insect pests still cause economic losses, among these the pink sugarcane mealybug Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Pseudococcidae) causing direct and indirect damage to the plant. This study assess the virulence of three entomopathogenic nematodes (EPNs) species and their symbiont bacteria against the pink sugarcane mealybug, under laboratory conditions. Fourteen treatments represented by control (distilled water), Heterorhabditis bacteriophora Poinar, 1976 (HB EN01) (Rhabditida: Heterorhabditidae), Steinernema rarum (Doucet, 1986) (PAM25) and Steinernema carpocapsae Weiser, 1955 (All) (Rhabditida: Steinermatidae) at concentrations of 25, 50, 75 and 100 infective juveniles (IJs)/insect, and the standard chemical product, thiamethoxam, were assayed. In a second experiment, the bacteria Photorhabdus luminescens (Thomas and Poinar, 1979), Xenorhabdus szentirmaii Lengyel, 2005 and Xenorhabdus nematophila (Poinar and Thomas, 1965) (Enterobacterales: Morganellaceae) at 3.0 x 109 cells/ml were assessed for each treatment. Ten replications were stablished, each one counting ten females/mealybugs inside a 10 cm Petri dish, amounting 100 individuals/treatment. All treatments were kept under stable conditions (25±1 ºC, H 70±10%, in the dark). All nematodes species infected S. sacchari. Steinerma rarum (PAM25) provided the highest mortality against the pink sugarcane mealybug (79.25%), followed by H. bacteriophora (HB EN01) (58.25%) and S. carpocapsae (All) (42.50%) (P<0.001). The mortality rate caused by X. szentirmaii, P. luminescens and X. nematophila were 40, 45 and 20%, respectively. Steinerma rarum (PAM25) has conditions to be a potential agent to be incorporate into the integrated pest management in sugarcane.

Highlights

IntroductionSugarcane crop Saccharum spp. (Poales: Poaceae) is important to the world as producing ethanol, sugar and bioenergy, standing out Brazil the world’s largest producer and exporter of sugarcane derivatives (Embrapa, 2020).In this production, many insect pests provoke economic losses, and among them, scale insects (Hemiptera: Coccoidea) cause direct and indirect damage that affect the phenology of the plant (Novoa et al, 2015; Jayanthi et al, 2016; Mohamed et al, 2009; Monteiro et al, 2021b).There are 18 species of scale insects associated to sugarcane in Brazil (Monteiro et al, 2019)
Steinernema rarum (PAM25) provided the highest mortality to the pseudococcid (79.25%), followed by H. bacteriophora (HB EN01) (58.25%) and S. carpocapsae (All) (42.50%) (P
Similar results were obtained by EL Roby (2018), with Steinernema spp. and Heterorhabditis spp. against S. sacchari, with mortality up to 48.7 and 70.8%, respectively

Summary

Introduction

Sugarcane crop Saccharum spp. (Poales: Poaceae) is important to the world as producing ethanol, sugar and bioenergy, standing out Brazil the world’s largest producer and exporter of sugarcane derivatives (Embrapa, 2020).In this production, many insect pests provoke economic losses, and among them, scale insects (Hemiptera: Coccoidea) cause direct and indirect damage that affect the phenology of the plant (Novoa et al, 2015; Jayanthi et al, 2016; Mohamed et al, 2009; Monteiro et al, 2021b).There are 18 species of scale insects associated to sugarcane in Brazil (Monteiro et al, 2019). (Poales: Poaceae) is important to the world as producing ethanol, sugar and bioenergy, standing out Brazil the world’s largest producer and exporter of sugarcane derivatives (Embrapa, 2020). In this production, many insect pests provoke economic losses, and among them, scale insects (Hemiptera: Coccoidea) cause direct and indirect damage that affect the phenology of the plant (Novoa et al, 2015; Jayanthi et al, 2016; Mohamed et al, 2009; Monteiro et al, 2021b). Sucking habit of S. sacchari facilitates the entry of phytopathogenic microorganisms, being a vector of the Sugarcane Bacilliform Virus (ScBv) (Autrey et al, 1995)

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