# Effect of Pyrethroids on the Colony Growth and Metabolic Activity of Entomopathogenic Fungi of the Beauveria Genus

## TL;DR

This study examines how different doses of pyrethroid insecticides affect the growth and metabolism of Beauveria fungi, which are used as biopesticides.

## Contribution

The study reveals that λ-cyhalothrin at recommended doses has minimal negative effects on B. bassiana and no effect on B. brongniartii.

## Key findings

- λ-cyhalothrin at the recommended field dose limited B. bassiana growth the least among tested pyrethroids.
- λ-cyhalothrin increased the metabolic activity of B. bassiana at recommended and lower doses.
- Deltamethrin significantly reduced the viability of B. brongniartii at all tested concentrations.

## Abstract

The aim of the study was to determine the effect of different doses of tested pyrethroids on the colony growth and metabolic activity of EPF from the Beauveria genus. In vitro, the effect of three pyrethroids (deltamethrin, λ-cyhalothrin, and α-cypermethrin) added to SDA medium at a dose 10 times lower than the recommended field dose (A), the recommended field dose (B), and 10 times higher than the recommended field dose (C) on colony growth and metabolic activity of B. bassiana and B. brongniartii was tested. The studies conducted showed that on the 20th day of the observation, λ-cyhalothrin used in the recommended field dose limited the growth of B. bassiana to the least extent in relation to the other tested pyrethroids. However, with respect to the fungus B. brongniartii, no toxic effect of this pyrethroid was found. λ-cyhalothrin used in the recommended field dose and 10 times lower than recommended significantly increased the metabolic activity of B. bassiana. Deltamethrin used in each of the tested concentrations significantly affected B. brongniartii viability.

Pyrethroids are chemical insecticides used on a large scale in agriculture, horticulture, and forest protection. In order to reduce their use in IPM, alternative methods of controlling insect pests are introduced, such as the use of biopesticides based on entomopathogenic fungi (EPF). Species of the Beauveria genus are characterized by a very broad spectrum of action, which is why they are often used to produce preparations based on EPF. The aim of the study was to determine the effect of different doses of tested pyrethroids on the colony growth and metabolic activity of EPF from the Beauveria genus. In vitro, the effect of three pyrethroids (deltamethrin, λ-cyhalothrin, and α-cypermethrin) added to SDA medium at a dose 10 times lower than the recommended field dose (A), the recommended field dose (B), and 10 times higher than the recommended field dose (C) on colony growth and metabolic activity of B. bassiana and B. brongniartii was tested. The research carried out showed that pyrethroid insecticides used in the experiment showed various toxic effects towards the tested EPF of the genus Beauveria. The studies conducted showed that on the 20th day of the observation, λ-cyhalothrin used in the recommended field dose limited the growth of B. bassiana to the least extent in relation to the other tested pyrethroids. However, with respect to the fungus B. brongniartii, no toxic effect of this pyrethroid was found. Based on the results obtained, it was found that λ-cyhalothrin used in the recommended field dose and 10 times lower than recommended significantly increased the metabolic activity of B. bassiana. In relation to the B. brongniartii strain, detlamethrin used in each of the tested concentrations significantly affected its viability.