# Unlocking the Potential of Bacillus Strains for a Two-Front Attack on Wireworms and Fungal Pathogens in Oat

## TL;DR

Scientists found two soil bacteria that can help oat plants grow better and protect them from pests and fungi, offering a natural alternative to chemical pesticides.

## Contribution

Two Bacillus strains were identified that simultaneously promote oat growth and combat wireworms and Fusarium fungi.

## Key findings

- Bacillus velezensis BHC 3.1 reduced wireworm damage by 63.33% and inhibited multiple Fusarium species.
- Oats treated with the bacteria showed increased biomass, grain yield, and nitrogen content.
- The strains show potential as sustainable bio-inoculants for pest and disease control in oat crops.

## Abstract

Oats are an important crop for human nutrition and animal feed, but they can be damaged by both insects and fungi. In particular, wireworms and Fusarium fungi can attack the roots and other parts of the plant, making it weaker and reducing yield. Traditional chemical pesticides are becoming less effective against these pests and fungi, so scientists are looking for alternative, environmentally friendly solutions. In this study, we tested bacteria from the soil around oat roots to see if they could help plants grow better while also protecting them from pests and diseases. Two bacteria, Bacillus velezensis BHC 3.1 and Bacillus thuringiensis BHC 2.4, were especially effective. They reduced damage caused by wireworms and slowed the growth of several Fusarium fungi. When oats were treated with these bacteria in pot experiments, plants grew bigger, produced more seeds, and had higher nitrogen content than untreated plants. These findings show that these bacterial strains could be used as natural bio-inoculants to improve oat growth and protect against pests and diseases, offering a sustainable alternative to chemical pesticides.

(1) Background: Oat (Avena sativa L.) is a crop that is widely used in human nutrition, while it also plays an important role in animal husbandry as a high-quality forage crop. However, this crop is particularly susceptible to combined biotic stressors, including insect pests (Agriotes lineatus) and fungal infections (Fusarium spp.). These stresses act synergistically: root damage caused by wireworms increases the plant’s susceptibility to fungal infection, while pathogens further limit nutrient uptake and root system development. In recent years, the reduced efficacy of chemical pesticides against both insect pests and fungal pathogens has highlighted the need for alternative strategies in oat protection, leading to an increased focus on developing bacterial bio-inoculants as sustainable and effective biocontrol agents. (2) Methods: This study aimed to identify bacterial strains capable of suppressing wireworms (Agriotes lineatus) and Fusarium spp. in oats, while simultaneously promoting plant growth. Bacterial isolates were screened for key Plant Growth Promoting (PGP) and biocontrol traits, including IAA and siderophore production, phosphate solubilization, and the presence of toxin- and antibiotic-coding genes. (3) Results: The highest insecticidal effect against wireworms was recorded for Bacillus velezensis BHC 3.1 (63.33%), while this isolate also suppressed the growth of F. proliferatum for 59%, F. oxysporum for 65%, F. poae for 71%, and F. graminearum for 15%. The most effective Bacillus strains (with insecticidal and antifungal activity) were identified and tested in two pot experiments, where their ability to enhance plant growth in the presence of insects and fungi was evaluated under semi-controlled conditions. An increase in plant biomass, grain yield, and nitrogen content was observed in oat inoculated with B. velezensis BHC 3.1 and B. thuringiensis BHC 2.4. (4) Conclusions: These results demonstrate the strong potential of both strains as multifunctional bio-inoculants for enhancing oat growth and mitigating the adverse effects of wireworm damage and Fusarium infection.