A spray-dried microencapsulated<i> Bacillus</i><i> thuringiensis</i> subsp.<i> kurstaki</i> formulation with enhanced environmental stability while maintaining insecticidal efficacy against lepidopteran pests
CROP PROTECTION, cilt.211, 2027 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 211
- Basım Tarihi: 2027
- Doi Numarası: 10.1016/j.cropro.2026.107848
- Dergi Adı: CROP PROTECTION
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Environment Index, Geobase, Zoological Record
- Karadeniz Teknik Üniversitesi Adresli: Evet
Özet
A spray-dried starch-protein-based microencapsulated wettable powder formulation (SP-Btk-WP) was developed from a local isolate of Bacillus thuringiensis subsp. kurstaki (Btk-Bn1) and evaluated for its physicochemical properties, environmental stability, and laboratory and field performance against major lepidopteran pests. Preliminary growth assessment indicated favorable bacterial growth under near-neutral pH conditions and at 30 degrees C. The developed formulation exhibited a high viable spore content (3 & times; 1010 CFU/g), acceptable moisture content (8.01%), rapid wettability (15 s), and high suspensibility (80%); scanning electron microscopy confirmed the successful microencapsulation of spores and crystals. Accelerated storage experiments at 54 +/- 1 degrees C demonstrated significantly improved thermal stability of the SP-Btk-WP formulation compared with the unformulated spray-dried preparation. Similarly, the formulated product retained significantly higher viable spore counts and relative spore survival after prolonged UV-B exposure, indicating the enhanced photoprotective capacity of the starch-protein matrix. Laboratory bioassays against second-instar Spodoptera littoralis larvae confirmed that the formulation preserved considerable insecticidal activity despite slightly lower acute toxicity relative to unformulated spores. Field trials further demonstrated strong efficacy against Tuta absoluta in tomato greenhouses and Lobesia botrana in vineyards. At the highest tested application rates, the field efficacy of SP-Btk-WP did not differ significantly from that of the corresponding commercial reference treatments under the conditions of the respective field experiments. Overall, these findings demonstrate that integrating spray drying with a starch-- protein microencapsulation matrix improves physicochemical quality, thermal storage stability, and protection against UV-B irradiation while maintaining effective field efficacy under the conditions evaluated, supporting the potential of this formulation as a practical Bt-based biopesticide for sustainable management of lepidopteran pests.