First Screening of Entomopathogenic Nematodes and Fungus as Biocontrol Agents against an Emerging Pest of Sugarcane, Cacosceles newmannii (Coleoptera: Cerambycidae).

John S Terblanche,Desmond E Conlong,Marion Javal,Antoinette P Malan

doi:10.3390/insects10040117

John S Terblanche, Desmond E Conlong + Show 2 more

Open Access

https://doi.org/10.3390/insects10040117

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Abstract

Cacosceles newmannii (Coleoptera: Cerambycidae) is an emerging pest of sugarcane in South Africa. The larvae of this cerambycid beetle live within the sugarcane stalk and drill galleries that considerably reduce sugar production. To provide an alternative to chemical control, entomopathogenic nematodes and fungus were investigated as potential biological control agents to be used in an integrated pest management system. The nematodes Steinernema yirgalemense, S. jeffreyense, Heterorhabditis indica, and different concentrations of the fungus Metarhizium pinghaense were screened for efficacy (i.e., mortality rate) against larvae of C. newmannii. The different biocontrol agents used, revealed a low level of pathogenicity to C. newmannii larvae, when compared to control treatments.

Highlights

The longhorned beetle Cacosceles newmannii Thompson 1877 is a cerambycid native to Mozambique, eSwatini and South Africa
This study is the first to assess the virulence of entomopathogenic nematodes (EPNs) and an entomopathogenic fungus in the context of biocontrol of larvae of the cerambycid C. newmannii
Larvae of this emerging crop pest appear to be resistant to the different EPN and entomopathogenic fungi (EPF) species used in this study

Summary

Introduction

The longhorned beetle Cacosceles newmannii Thompson 1877 is a cerambycid native to Mozambique, eSwatini and South Africa. The biology of this beetle is poorly known, and its host plants have not yet been fully determined, but might include species from the Myrtaceae family [1]. Cacosceles newmannii larvae were found in 2015 feeding on commercially grown sugarcane in the KwaZulu-Natal province of South Africa. Larvae dig galleries into the sugarcane stool and upwards from 8 to 20 cm into the bottom section of the stalk, but are most of the time found in the below-ground section of the sugarcane stalks, in the stool [2]. The reasons underlying the host shift of C. newmannii onto sugarcane remain unclear [3]. Regardless of the factor(s) determining the switch to sugarcane, this species has the potential to spread and cause considerable losses

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