Virulence of the entomopathogenic fungusLecanicillium(Deuteromycota: Hyphomycetes) toPissodes strobi(Coleoptera: Curculionidae)

Abstract

The widely occurring fungal genus Lecanicillium Zare & W. Gams (formerly Verticillium) includes species that are pathogenic to insects. We collected 27 Lecanicillium isolates from soil and from dead adult Pissodes strobi (Peck) in British Columbia, Canada, and assessed their virulence against this host. Eighteen isolates were identified as L. longisporum (Petch) Zare & W. Gams and six as L. muscarium (Petch) Zare & W. Gams, while three isolates could not be identified to the species level. We assayed a subset of these isolates (14 L. longisporum, 3 L. muscarium, and 1 Lecanicillium sp.) as well as the fungal component of the commercial products Mycotal® (L. muscarium) and Vertalec® (L. longisporum) and a herbarium isolate (Lecanicillium sp.). When adult weevils were inoculated with a conidial suspension (1 × 107 conidia/mL), mycosis-related mortality at the end of a 17-day incubation period varied between 20% and 100%, depending on the isolate tested. Eight of the isolates killed >75% of weevils: a Lecanicillium sp. isolate, PFC19, which displayed the lowest LT50 value; five indigenous L. longisporum isolates; and both commercial products. In a goodness-of-fit test comparing isolate virulence among species, the unidentified PFC19 isolate was found to be more effective than either L. longisporum or L. muscarium, while L. longisporum caused somewhat greater mortality than L. muscarium. In a similar analysis, isolates extracted from soils tended to be more effective than those obtained from cadavers. Horizontal transmission to live P. strobi was observed using different isolates of Lecanicillium species. Notwithstanding the variability in virulence, the indigenous Lecanicillium species that we isolated and assayed are confirmed as pathogenic to P. strobi in British Columbia.

Fungal isolate and crop cultivar influence the beneficial effects of root inoculation with entomopathogenic fungi in strawberry

“…The inter‐ and intraspecific variability of entomopathogenic fungi in virulence against pests has been widely reported along with the variations associated to fungal morphophysiological characteristics and geographical origin . Conversely, the variability of the indirect effects of entomopathogenic fungi used as plant inoculants against pests has not been investigated.…”

Effects of temperature and water activity on Lecanicillium spp. conidia germination and growth, and mycosis of Pissodes strobi

“…Pure isolates of Lecanicillium were produced by suspending a drop of sterile water from the end of a hypodermic needle then touching this drop onto conidiophores resulting in the hydrophilic conidia (Inglis et al 2001;Hajek 1997) migrating into the droplet. The droplet was spread over the surface of a Lecanicillium-selective medium (LSM, Kope et al 2006). After 6 h incubation, open Petri plates were observed under a compound microscope at 50· magnification and single germinated conidia were removed and sub-cultured onto Sabouraud Dextrose Agar (SDA, Ingles et al 2001), grown on for 14 days, and then stored at 58C until needed.…”

An investigation onLecanicillium muscariumas a biocontrol agent of stem borer pests ofRosa damascenain Kerman Province of Iran

“…Finally, the pH was adjusted to 4.0 with 10% H 3 PO 4 . Other culture media were Sabouraud dextrose agar (SDA), Potato dextrose agar (PDA), Malt agar (MA) and SDA þ YE (Kope et al 2006).…”

“…After incubation, three droplets of lactophenol cotton blue stain (0.5% cotton blue) were added to each Petri plate to fix and stain the conidia and to prevent any further germination. The droplets were covered with a glass slide and evaluated using 4006 phase contrast magnification (Hsiao et al 1992;Kope et al 2006).…”