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Compatibility of different Metarhizium spp. propagules with synthetic acaricides for controlling Rhipicephalus
Adriani da Silva Carneiro1, Emily Mesquita1, Laura Nóbrega Meirelles1
1Programa de Pós-graduação em Ciências Veterinárias, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro - UFRRJ, Seropédica, RJ, Brasil.
Abstract:
The inappropriate use of synthetic acaricides has selected resistant Rhipicephalus microplus populations. The present study evaluated the compatibility of different Metarhizium spp. propagules (conidia, blastospores, and microsclerotia) by incubating them with synthetic acaricides (amitraz, deltamethrin, and a combination of cypermethrin, chlorpyrifos, and citronellal) for 1 h, 5 h, 10 h, and 24 h. Conidia and microsclerotia of the tested isolates were usually more tolerant to synthetic acaricides than blastospores. Our study also analyzed the in vitro effect of deltamethrin associated with fungal propagules for controlling a population of R. microplus females that were not susceptible to this synthetic acaricide. The use of entomopathogenic fungi in association with deltamethrin in this tick population caused a greater tick control than did the use of the fungus or the synthetic acaricide separately.
Insights
This study explored combining Metarhizium fungi with synthetic acaricides to control resistant Rhipicephalus microplus ticks. Fungal conidia and microsclerotia showed better tolerance to acaricides, enhancing tick control when used together.
Area of Science:
- Veterinary Entomology
- Agricultural Mycology
- Pest Management
Background:
- Synthetic acaricide overuse has led to resistant Rhipicephalus microplus populations, a significant threat to cattle health.
- Developing integrated pest management strategies is crucial for sustainable tick control.
- Metarhizium spp. are entomopathogenic fungi with potential for biological control of arthropod pests.
Purpose of the Study:
- To evaluate the compatibility of different Metarhizium spp. propagules (conidia, blastospores, microsclerotia) with common synthetic acaricides.
- To assess the efficacy of combining Metarhizium spp. with deltamethrin against acaricide-resistant Rhipicephalus microplus.
- To determine the optimal combination strategy for enhanced tick control.
Main Methods:
- Incubation of Metarhizium spp. propagules with synthetic acaricides (amitraz, deltamethrin, cypermethrin/chlorpyrifos/citronellal) for various durations (1-24 h).
- In vitro assessment of fungal propagule survival and efficacy.
- Evaluation of the combined effect of deltamethrin and fungal propagules on Rhipicephalus microplus female mortality.
Main Results:
- Conidia and microsclerotia of Metarhizium spp. demonstrated greater tolerance to synthetic acaricides compared to blastospores.
- The combination of Metarhizium spp. and deltamethrin resulted in superior control of Rhipicephalus microplus compared to individual treatments.
- This synergistic effect was observed even against a Rhipicephalus microplus population resistant to deltamethrin.
Conclusions:
- Metarhizium spp. conidia and microsclerotia are compatible with synthetic acaricides, offering a basis for integrated tick management.
- Combining entomopathogenic fungi with synthetic acaricides presents a promising strategy to overcome acaricide resistance in Rhipicephalus microplus.
- This integrated approach enhances tick control efficacy, contributing to more sustainable livestock pest management.
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