Assessment of combining biosynthesized silver nanoparticles using Bacillus thuringiensis and gamma irradiation for controlling Pectinophora gossypiella (saunders) (lepidoptera: Gelechiidae)

Abstract

Purpose

Combining gamma irradiation and nanotechnology has become one of the most promising new approaches for area-wide (AW) pest management in recent years. The laboratory trials were conducted to determine the combining effects of BT-AgNPs and gamma irradiation for controlling P. gossypiella. Radio-sensitivity of male pupae at different doses of gamma radiation and the effectiveness of biosynthesized silver nanoparticles using Bacillus thuringiensis on larval instar were assayed. Additionally, the ultrastructure changes on the alimentary canal of 4^th instar larvae were studied to evaluate the impact of the combined approach at a cellular level.

Materials and methods

Laboratory- rearing technique was used for rearing Pectinophora gossypiella. The irradiation process was achieved at Co⁶⁰ - Gamma Chamber (4000 A). Alanine dosimeters were used for measuring the average absorbed dose and dose mapping. Preparation of Silver nanoparticles (AgNPs) using Bacillus thuringiensis (Bt) and their characterization has been investigated. The treated 4^th instar larvae by gamma irradiation or ∕and BT-AgNPs were dissected under the stereo microscope. The alimentary canal was obtained anatomically and Transmission Electron Microscope) was used in examining the stained sections.

Results

Based on the nonhatching eggs produced by irradiated males’ pupae, the values of effective doses were calculated. The effective doses ranged from 16 to 291 Gy for the ED₂₅ - ED₇₅. The sterility index reached 74.1% when irradiated with males by 291 Gy crossed with nonirradiated females and the adult emergence decreased to be 35.3%. The insecticidal potential of Bt-AgNPs on the 2^nd and 4^th larval instars was dose-dependent and its LC₅₀ toxicity value was 0. 3 and 0. 4 mg/ml, respectively. The lethal concentration LC₅₀ of the 2^nd instar larvae increased the larval and pupal mortality to 55% and 44.4%, respectively, and reduced the adult emergence to be 55.6%. The combining effects of Bt-AgNPs with 291 Gy induced 100% pupae mortality and there was no adult emergence in F1 generation. Such effects also severed the ultrastructure deformity of the midgut of the 4^th instar larvae after the two-day post-treatment.

Conclusions

The combining effects are recommended as an effective IPM program to control P. gossypiella by releasing sterile males (derived from pupae irradiated with 291 Gy) crossing with the normal females in the field, and reducing the fertility of the population to 31.2%. Subsequently, the resulted larvae treated with LC₅₀ of Bt-AgNPs prevented the adult emergence and stopped the life cycle of P. gossypiella.

Keywords:

• Bt-AgNPs
• gamma irradiation
• midgut-ultrastructure
• Pectinophora gossypiella

Disclosure statement

In accordance with Taylor & Francis policy and my ethical obligation as a researcher, I am reporting that I have not financial or business interests in a company that may be affected by the research reported in the enclosed paper. I have disclosed those interests fully to Taylor & Francis, and I have in place an approved plan for managing any potential conflicts arising from [that involvement].

Additional information

Notes on contributors

Ahlam Gabarty

Ahlam Gabarty, PhD, is an Associate Professor of Entomology at the National Center for Radiation Research and Technology, Egyptian Atomic Energy. Her researches are focused on topics related to sterile insect techniques, area-wide (AW) pest management, phytosanitary irradiation treatment. She has been enrolled in International Atomic Energy Agency (IAEA) Coordinated Research Projects. She is Secretary general of Egyptian Society of Radiation Sciences and Applications; Associate editor-in-chief of Journal of Radiation Research and Applied Sciences “Taylor and Francis”, and one the supervisors of this research.

Afaf Abas

Afaf Abas, PhD, is a Professor of Entomology at the Department of Zoology and Entomology, Faculty of Science, Al-Azhar University, Cairo, Egypt. Her researches are focused on topics related to embryology and ultrastructure examination of insects. She is one the supervisors of this research.

Hedaya M. Salem

Hedaya M. Salem, PhD, a Professor of Entomology and former Chairman of Biotechnology Division at National Center for Radiation Research and Technology, Egyptian Atomic Energy. Her researches are focused on topics related to sterile insect techniques. She is the Chief of Egyptian Society of radiation Sciences and Applications, Editor-in-chief of Journal of Radiation Research and Applied Sciences “Taylor and Francis”, and one the supervisors of this research.

Sawsan M. El-Sonbaty

Sawsan M. El-Sonbaty, PhD, is a Professor of Microbiology at the National Center for Radiation Research and Technology, Egyptian Atomic Energy. Her researches are focused on topics related to radiation microbiology and biotechnology. She is one the supervisors of this research.

Doaa S. Farghaly

Doaa S. Farghaly, PhD, is an Associate Professor of Entomology at the Department of Zoology and Entomology, Faculty of Science, Al-Azhar University, Cairo, Egypt. Her researches are focused on topics related to Integrated Pest Management. She is one the supervisors of this research.

Heba A. Awad

Heba A. Awad, M.Sc., is a Researcher of Entomology at the Department of Zoology and Entomology, Faculty of Science, Al-Azhar University, Cairo, Egypt. She is the main researcher of this paper which is a part of her Master’s degree.