Biocontrol fungal seed pelletization for soil pest management in cruciferous and solanaceous crops

Overview

Soil pests including insects, nematodes, and phytopathogens cause serious damage to crop production worldwide. Biocontrol fungi such as Metarhizium, Isaria, Purpureocillium, and Trichoderma play an important role in controlling these pests, but conventional seed treatment often fails for cruciferous and solanaceous crops whose thousand-seed weight is below 5 grams. The small seed size limits how much conidia (fungal spores) can adhere to the seed surface, resulting in inadequate pest control against threats such as striped flea beetles and bacterial wilt.

This solution pelletizes small seeds with biocontrol fungal conidia, increasing the conidia loading per seed and substantially improving pest control effectiveness. The approach has been validated first with chemical pesticides and then with screened strains of Metarhizium anisopliae and Isaria javanica on Brassica campestris seeds. Primary results indicate that pelletized seeds show stronger resistance to striped flea beetles and improved plant growth compared with conventional treatment.

Technical specifications

Target crops: Cruciferous vegetables (including Brassica campestris ssp. chinensis var. utilis) and solanaceous crops with small seeds.

Biocontrol agents: Conidia of screened strains of Metarhizium anisopliae, Isaria javanica, and related fungal genera (Purpureocillium, Trichoderma) with activity against soil insects, nematodes, and phytopathogens.

Key features:

• Pelletization increases conidia loading per seed compared with conventional seed coating
• Adjuvants and dosages are selected and optimized to maintain fungal viability
• Pelletizing factors and parameters are tuned for seed compatibility and germination
• Bioactivity and stability of the formulations are monitored

Research focus areas:

• Development of two to three pelletizing technologies for cruciferous seeds targeting striped flea beetle control
• Exploration of foundational technology for seed pelletization with biocontrol fungi

Technology readiness level

The technology is at an early-to-mid development stage. Proof of concept has been demonstrated through chemical pesticide pelletization validation, and laboratory experiments with Metarhizium anisopliae and Isaria javanica on Brassica campestris seeds have produced encouraging primary results showing improved resistance to striped flea beetles and better plant growth. Ongoing and planned work includes laboratory optimization (2020-2021) covering adjuvant selection, pelletizing parameter optimization, and bioactivity and stability testing, followed by field trials (2021-2022) to evaluate effectiveness against target pests and refine application methods. The technology is not yet commercially deployed and requires further field validation before scale-up.