Effect of gamma irradiation on the susceptibility of the cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) to the infection with nucleopolyhedrosis virus

Waheed Ahmed Abd-Elhamid Sayed,Alexandra Magdalina Ahmed El-Helaly

doi:10.1186/s41938-018-0082-8

Waheed Ahmed Abd-Elhamid Sayed, Alexandra Magdalina Ahmed El-Helaly

Open Access

https://doi.org/10.1186/s41938-018-0082-8

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Abstract

The sensitivity of irradiated cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), to infection with nucleopolyhedrosis virus (SpliNPV) was evaluated. S. littoralis pupae were irradiated by four low doses of gamma radiation, 40, 60, 80, and 100 Gy, and the sensitivity to viral infection of the resultant F1 larvae was evaluated. The results indicated that the irradiated F1 larvae showed high sensitivity to different SpliNPV concentrations. In the case of 1 × 103 PIBs/ml concentration, the mortality percentages of F1 larvae drastically increased to 25.14, 46.53, 93.2, and 91.3% at the doses 40, 60, 80, and 100 Gy, respectively, in comparison to 4.9% for the un-irradiated treatment. The results revealed that the numbers of deposited eggs, hatched eggs, and survived larvae and pupae were reduced at all the radiation doses as compared to the control treatment. The results indicated that 40 and 60 Gy were the effective doses for irradiating S. littoralis male pupae to produce F1 larvae very sensitive to SpliNPV which may help in baculovirus mass production.

Highlights

Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is an economically important polyphagous pest in Egypt
Bioassay analysis A local isolate of S. littoralis multiple embedded nucleopolyhedrosis virus (SpliNPV) was used in the experimental studies originally isolated in Egypt by Abul Nasr (1956)
The present study investigated some biological parameters of S. littoralis that could be affected by the low doses of gamma radiation applied to increase NPV production

Summary

Introduction

Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is an economically important polyphagous pest in Egypt. A multifaceted approach is required because of the many records of resistance developing in this insect to several groups of pesticides (Ramakrishnan et al 1984 ; Armes et al 1997). Microbial insecticides such as baculoviruses are environmentally safe and selective bio-insecticides and can be used as alternatives to chemical pesticides (Armenta et al 2003). Baculovirus products are commercially available with trade names for use in certain parts of the world (Black et al 1997); the use of one or a combination of techniques to increase the efficacy of baculovirus production is still needed. The reduction in production time or the use of alternative hosts or vectors may enhance the efficiency of baculovirus production (Monobrullah et al 2007; Beek and Davis 2007)

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