Related Experiment Video
Updated: Jul 16, 2025
Isolation and Selection of Entomopathogenic Fungi from Soil Samples and Evaluation of Fungal Virulence against Insect Pests
Published on: September 28, 2021
Metarhizium pingshaense photolyase expression and virulence to Rhipicephalus microplus after UV-B exposure
Pamella Pryscila de A B M de Lima1, Jessica Fiorotti1,2, Patrícia G Paulino1
1Programa de Pós-Graduação em Ciências Veterinárias, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropédica, Rio de Janeiro, Brazil.
Abstract:
The current study examined the impact of ultraviolet (UV)-B radiation in Metarhizium pingshaense blastospores' photolyase expression and their virulence against Rhipicephalus microplus. Blastospores were exposed to UV under laboratory and field conditions. Ticks were treated topically with fungal suspension and exposed to UV-B in the laboratory for three consecutive days. The expression of cyclobutane pyrimidine dimmers (CPDs)-photolyase gene maphr1-2 in blastospores after UV exposure followed by white light exposure was accessed after 0, 8, 12, 24, 36, and 48 h. Average relative germination of blastospores 24 h after in vitro UV exposure was 8.4% lower than 48 h. Despite this, the relative germination of blastospores exposed to UV in the field 18 h (95.7 ± 0.3%) and 28 h (97.3 ± 0.8%) after exposure were not different (p > 0.05). Ticks treated with fungus and not exposed to UV exhibited 0% survival 10 days after the treatment, while fungus-treated ticks exposed to UV exhibited 50 ± 11.2% survival. Expression levels of maphr1-2 8, 12, and 24 h after UV-B exposure were not different from time zero. Maphr1-2 expression peak in M. pingshaense blastospores occurred 36 h after UV-B exposure, in the proposed conditions and times analyzed, suggesting repair mechanisms other than CPD-mediated-photoreactivation might be leading blastospores' germination from 0 to 24 h.
Insights
UV-B radiation impacts Metarhizium pingshaense blastospores, affecting their photolyase gene expression and virulence against Rhipicephalus microplus ticks. UV exposure enhanced fungal efficacy against ticks, suggesting complex repair mechanisms in blastospores.
Area of Science:
- Mycology
- Entomology
- Molecular Biology
Background:
- Metarhizium pingshaense is a fungus with potential as a biopesticide.
- Rhipicephalus microplus is a significant cattle tick pest.
- Ultraviolet (UV) radiation can affect microbial survival and virulence.
Purpose of the Study:
- To investigate the effect of UV-B radiation on Metarhizium pingshaense blastospore photolyase expression.
- To assess the impact of UV-B radiation on the virulence of M. pingshaense against Rhipicephalus microplus ticks.
Main Methods:
- Blastospores were exposed to UV-B under laboratory and field conditions.
- Ticks were treated with fungal suspension and exposed to UV-B.
- Cyclobutane pyrimidine dimers (CPDs)-photolyase gene (maphr1-2) expression was measured post-UV exposure.
- Tick survival rates were recorded.
Main Results:
- UV-B exposure did not significantly alter relative germination of blastospores in field conditions at 18 and 28 hours.
- Fungus-treated ticks exposed to UV-B showed 50% survival, while those not exposed had 0% survival.
- maphr1-2 gene expression peaked 36 hours after UV-B exposure, indicating potential repair mechanisms beyond CPD-photoreactivation.
Conclusions:
- UV-B radiation enhances the virulence of Metarhizium pingshaense against Rhipicephalus microplus.
- The photolyase gene maphr1-2 shows a delayed peak expression, suggesting complex UV response pathways in blastospores.
- UV-B treatment could be a viable strategy to improve the efficacy of M. pingshaense as a biological control agent for ticks.
