Potential of standard strains of Bacillus thuringiensis against the tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Abstract

Background The tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the key pests of tomato worldwide, causing an estimated crop loss of 80 to 100%. This pest has developed resistance to several pesticides due to overuse, resulting in control failures in the field. The use of biological insecticides as Bacillus thuringiensis that expressed insecticidal proteins can be an alternative tool by insecticides to suppress the pest population. Main body Laboratory study investigated the efficacy of standard Bacillus thuringiensis (Bt) strains (4D1, 4D4, 4G1, 4K5 and 4XX4) against T. absoluta. Bioassay was conducted using tomato leaf discs treated with spore crystal lysates prepared from the standard strains, and mortality data was subjected to concentration-mortality probit analysis. The LC50 values for Bt 4D1, Bt 4D4 and Bt 4G1 were 6.10, 6.62 and 8.18 μg/ml for the 2nd instar; 9.90, 10.20 and 11.12 μg/ml for the 3rd instar; and 19.82, 23.16 and 24.54 μg/ml for the 4th instar, respectively, while the Bt 4K5 and Bt 4XX4 were not toxic to T. absoluta. Conclusion This study suggests that Bt strain 4D1 is effective against different larval instars of the pest and can be used in its management.

The Potential Activities of Two Bacillus thuringiensis Strains Against the Neonate Larvae of Pectinophera gossypiella

“…thuringiensis against the cotton leaf roller, Syllepte derogata (Gahramanova et al, 2020), Bacillus thuringiensis CAB109 on Spodoptera exigua (Huang et al, 2018), Bt against the pod borer, Helicoverpa armigera (Bouslama et al, 2020;Fite et al, 2019), Bt against P. gossypiella (Abbas et al, 2017). The LC50 values for Bt 4D1, Bt 4D4 and Bt 4G1 were 6.10, 6.62 and 8.18 μg/ml for the 2nd instar; 9.90, 10.20 and 11.12 μg/ml for the 3rd instar; and 19.82, 23.16 and 24.54 μg/ml for the 4th instar, respectively, while the Bt 4K5 and Bt 4XX4 were not toxic to Tuta absoluta (Sandeep Kumar et al, 2020).…”

Farklı Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) popülasyonlarının yerel Bacillus thuringiensis suşlarına duyarlılığı

“…Several studies have been conducted on the efficacy of Bt or Bt-based biopesticides on populations of T. absoluta. Sandeep Kumar et al (2020) tested the Bt strains (4D1, 4D4, 4G1) on the laboratory reared population and the LC50 values for the second larval stage were 6.10, 6.62 and 8.18 μg/ml, respectively. However, Sabbour & Soliman (2014) found that the LC50 values of the commercial product Dipel and the strains Bt kurstaki HD-73 and HD-234 were 140, 109, and 90 μg/ml, respectively, on the larvae of T. absoluta under laboratory conditions.…”

“…The crystal proteins shown to have lethal effect against different orders of insects such as Lepidoptera, Coleoptera, and Diptera. To date, local Bt isolates and Bt-based biopesticides have been tested to suppress T. absoluta populations under laboratory, greenhouse and open field conditions (Giustolin et al, 2001;Sandeep Kumar et al, 2020;Aynalem et al, 2021;Buragohain et al, 2021).…”