Natural prevalence of entomopathogenic fungi in hibernating pupae of Cameraria ohridella (Lepidoptera: Gracillariidae) and virulence of selected isolates

Abstract

Schemmer R., Chládeková P., Medo J., Barta M. (2016): Natural prevalence of entomopathogenic fungi in hibernating pupae of Cameraria ohridella (Lepidoptera: Gracillariidae) and virulence of selected isolates. Plant Protect. Sci., Spontaneous infection of hibernating Cameraria ohridella pupae by entomopathogenic fungi was monitored at two localities of south-western Slovakia and efficacy of selected fungal isolates against the pupae was evaluated in laboratory. Natural prevalence of fungal infection in pupal populations was low (< 7%) and varied depending upon collecting date, locality, year, and pathogen. Ten isolates of three fungal species, Beauveria pseudobassiana, Isaria fumosorosea, and I. farinosa, isolated from the naturally infected pupae and three isolates of non-insect origin of two fungi, B. bassiana and metarhizium anisopliae, were screened for colony growth, conidial production in vitro, and virulence to C. ohridella pupae. A significant variability in the evaluated traits was detected among the isolates. Pupae demonstrated vulnerability to all the isolates irrespective of their origin, however virulence of isolates varied significantly. I. fumosorosea was the most virulent fungus with median lethal concentration of 0.09 × 10 4 conidia/ml (isolate CO10-IFu) and mean survival time of pupae of 7.14 days (isolate CO8-IFu). No correlation between conidial yield of isolates and fungal virulence was observed, but a moderately strong relationship was detected between virulence and mycelial growth rate of isolates.

Efficacy of Beauveria bassiana and Beauveria pseudobassiana isolates against the pine processionary moth, Thaumetopoea wilkinsoni Tams, 1926 (Lepidoptera/Notodontidae)

“…Studies on the effectiveness of B. pseudobassiana in insects of the order Lepidoptera are few. Of these, Schemmer et al (2016) reported that six different B. pseudobassiana strains were applied to Cameraria ohridella Deschka & Dimić (Lepidoptera/Gracillariidae), and all strains caused 100% mortality on the tenth day. Gürlek et al (2018) stated that B. pseudobassiana caused death in Cydia pomonella Linnaeus (Lepidoptera/ Tortricidae).…”

Parasitoids and fungal pathogens of Phyllonorycter issikii (Kumata, 1963) from Bulgaria

“…The most widely distributed fungus in insects populations B. bassiana was registered in dead larvae or pupae of C. ohridella (Draganova and Tomov 2000b;Prenerová et al 2008;Metla et al 2013). Another fungal species isolated from the horse chestnut leafmining moth were Isaria fumosorosea Wize (Zemek et al 2007;Schemmer et al 2016), B. pseudobassiana S.A. Rehner & Humber and Isaria farinosa (Holmsk.) Fr.…”

“…Fr. (Schemmer et al 2016), fungi belonging to the genera Aspergillus, Hirsutella, Metarhizium and Lecanicillium (Metla et al 2013). As Schemmer et al (2016) reported the mean mortality rate of pupae due to fungal infection was low and it reached 4.20%; however, the level of mortality varied depending upon collecting date, locality, year, and fungus.…”

Fungi Associated with Horse-Chestnut Leaf Miner Moth Cameraria ohridella Mortality

“…However, information on C. ohridella-related fungal entomopathogens remains scarce, and most investigations of fungi involved in moth mortality have been performed in a single country only, namely in the Czech Republic [26][27][28][29][30]. Fungi belonging to the genera of known fungal entomopathogens (Beauveria Vuill., Lecanicillium W. Gams and Zare, Metarhizium Sorokin, and Paecilomyces Bainier) were isolated from C. ohridella habitat and some strains showed entomopathogenic activity against pupae and moth caterpillars [31][32][33][34][35]. Unfortunately, information on fungi virulence throughout moths' developmental stages remains scarce.…”