Susceptibility of adults of the cerambycid beetle Hedypathes betulinus to the entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, and Purpureocillium lilacinum.

M E Schapovaloff,L F A Alves,R A Alzogaray,A L Fanti,C C López Lastra,Paul Ode

doi:10.1093/jis/14.1.127

Abstract

The cerambycid beetle Hedypathes betulinus (Klug) (Coleoptera: Cerambycidae) causes severe damage to yerba mate plants ( Ilex paraguariensis (St. Hilaire) (Aquifoliales: Aquifoliaceae)), which results in large losses of production. In this study, the pathogenicity of entomopathogenic fungi of the species Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae), Metarhizium anisopliae sensu lato (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae), and Purpureocillium lilacinum (Thom) Luangsa-ard, Hywel-Jones, Houbraken and Samson (Hypocreales: Ophiocordycipitaceae) on yerba mate were evaluated. Fifteen isolates of B. bassiana , two of M. anisopliae , and seven of P. lilacinum on H. betulinus adults were analyzed under laboratory conditions. The raw mortality rate caused by B. bassiana isolates varied from 51.1 to 86.3%, and their LT 50 values varied between 8.7 and 13.6 d. The isolates of M. anisopliae caused 69.6‒81.8% mortality, and their LT 50 values varied between 7.4 and 7.9 d. In contrast, isolates of P. lilacinum were not pathogenic. M. anisopliae and B. bassiana isolates were pathogenic against H. betulinus adults, suggesting that they may be useful in biological control programs for insect pests of yerba mate.

Highlights

Ilex paraguariensis (Saint Hilaire) (Aquifoliales: Aquifoliaceae), plantations are attacked by many pests, including the cerambycid beetle Hedypathes betulinus (Klug) (Coleoptera: Cerambycidae), which causes severe damage resulting in economical loss in this crop (Casanello 1993)
The objective of this study was to determine the pathogenicity of B. bassiana, M. anisopliae, and P. lilacinum isolates on adults of H. betulinus under laboratory conditions
Leger et al (1992) suggested that insects’ susceptibility or resistance to a particular fungus can be determined by cuticle components at the beginning of the infection. Another aspect to be considered about the increase of pathogenicity is the B. bassiana production of extracellular enzymes in a nutritious culture medium, all of which are included in host cuticle penetration and, in the infection by the fungus; their expression is influenced by cuticle composition and its own genesis in the culture medium

Summary

Introduction

Ilex paraguariensis (Saint Hilaire) (Aquifoliales: Aquifoliaceae), plantations are attacked by many pests, including the cerambycid beetle Hedypathes betulinus (Klug) (Coleoptera: Cerambycidae), which causes severe damage resulting in economical loss in this crop (Casanello 1993). Conidia that adhere to the surface of the host release extracellular enzymes, including lipases, proteases, and chitinase that help breach the host’s chitinous exoskeleton (Pendland et al 1993, Freimoser et al 2003, Tscharntke et al 2005). These fungi have been documented to occur naturally in more than 750 species of hosts and have been used in the development of microbial insecticides (Hajek and St. Leger 1994, Inglis et al 2001, Shah and Pell 2003)

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Conclusion