Biocontrol of <i>Cassida vittata</i> Vill. (Coleoptera: Chrysomelidae) in Sugar Beet Crops Using <i>Streptomyces</i> sp. Strains
<i>Cassida vittata</i> Vill. is a major pest of sugar beet crops worldwide. This study evaluated the efficacy of <i>Streptomyces</i> sp. strains E23-2, E23-9, E23-3, and E25-12 in managing this pest under both laboratory bioassays (26 ± 2 °C, 60 ± 10% RH, and 12 h of photoper...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-02-01
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| Series: | Microbiology Research |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2036-7481/16/3/57 |
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| Summary: | <i>Cassida vittata</i> Vill. is a major pest of sugar beet crops worldwide. This study evaluated the efficacy of <i>Streptomyces</i> sp. strains E23-2, E23-9, E23-3, and E25-12 in managing this pest under both laboratory bioassays (26 ± 2 °C, 60 ± 10% RH, and 12 h of photoperiod) and field conditions. In the laboratory bioassays, insecticidal and repellent activities were assessed using topical and leaf dip methods. The insecticidal activity test involved five concentrations of bacterial suspensions (10<sup>2</sup> to 10<sup>10</sup> cfu. mL<sup>−1</sup> (Colony-Forming Units per milliliter)) against pest larvae and adults. Only E23-2 and E23-9 strains at concentrations of 10<sup>1</sup>⁰ and 10⁸ cfu. mL<sup>−1</sup>, exhibiting the highest insecticidal activity, were used for the field bioassay. Carbosulfan at 0.25 g/L served as a positive control. Results indicated E23-2’s high efficacy against <i>C. vittata</i>, with the lowest LC<sub>50</sub> values: 323.5 (larvae) and 5.1 × 10<sup>3</sup> (adults) cfu. mL<sup>−1</sup> in topical contact, and 1.9 × 10<sup>3</sup> (larvae) and 3.1 × 10<sup>4</sup> (adults) cfu. mL<sup>−1</sup> in the leaf dip method. LT<sub>50</sub> values of 3 days for larvae and adults in the topical contact method supported E23-2’s efficacy. E23-2, at 10<sup>1</sup>⁰ cfu. mL<sup>−1</sup>, displayed notable repellency against <i>C. vittata</i> adults (RI = 84.9% at 48 h). In field trials, Henderson–Tilton adjusted rates revealed E23-2’s substantial reductions of 88.6% (larvae) and 85.9% (adults), aligning closely with Carbosulfan’s efficacy. Enzymatic analysis underscored the versatile biocontrol attributes of E23-2, E23-3, and E23-9, providing insights for targeted pest management strategies. Field conditions, notably temperature, can influence the establishment and efficacy of EP bacteria. Further field studies are imperative for a comprehensive understanding of these influencing factors. |
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| ISSN: | 2036-7481 |