Aegorhinus superciliosus is an important pest on blueberry
(
Vaccinium corymbosum
L.) and other fruit trees. The use of
entomopathogenic fungi as
Metarhizium
spp. has been evaluated
for the control of this insect, but variability has been observed
among different strains. The aim of this study was to characterize
six promising strains of
Metarhizium spp. for the control of
A. superciliosus. The studied strains were QuM173c, Qu-M363,
Qu-M171a, Qu-M156a, Qu-M421, and Qu-M430, all of
which belonged to the Chilean Collection of Microbial Genetic
Resources (ChCMGR) of the Instituto de Investigaciones
Agropecuarias (INIA), Chile. Molecular characterization was
made by sequencing the ITS region (Internal Transcribed
Spacers, ITS-5.8S rDNA). The morphology of conidia was
evaluated through scanning electron microscopy and radial
colony growth was evaluated in potato dextrose agar (PDA),
Sabouraud dextrose agar (SDA), agar enriched with larvae of
Galleria mellonella
(Lepidoptera: Pyralidae) (GA), and agar
enriched with adults of
A. superciliosus (AA). Pathogenicity
was studied based on mortality of adults of
A. superciliosus
inoculated with conidia. Sequencing of the ITS-5.8S rDNA
region indicates that the strains belong to the clade of
M. anisopliae
var.
anisopliae, except for Qu-M171a, which was
identified as
M. anisopliae var.
lepidiotum. Conidia average
length for the six strains was 5.09
μm and average conidia
width was 1.92
μm. Radial colony growth differences were
observed between strains (p < 0.01) and between different
growth media (p < 0.01). The strains exhibited the highest
colony growth in the GA medium, while in the AA medium
they showed the lowest (p < 0.01). Pathogenicity tests show
that Qu-M430 reached a 90% mortality rate (p < 0.01). Results
show that there is variability between the studied strains, which
is expressed in their morphology, molecular characteristics and
pathogenicity towards
A. superciliosus.
