Infectivity prospects of both nematodes and bacterial symbionts against cotton leafworm, Spodoptera
littoralis (Biosduval) (Lepidoptera: Noctuidae) |
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| Authors: | A S Abdel-Razek |
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| Institution: | (1) Department of Pests and Plant Protection, National Research Centre, El-Tahrir Str, Dokki, Cairo, Egypt |
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| Abstract: | A study was made on the susceptibility of the cotton leafworm, Spodoptera littoralis (Biosd.), to the nematode, Steinernema carpocapsae (All) and Heterorhabditis bacteriophora. Three concentrations of each nematode species were used (75, 150, and 300 infective juveniles) for each treatment. The nematode,
H. bacteriophora, gave 100% mortality 96, 90, and 48 h, respectively, post-treatment of S. littoralis larvae with 75, 150, and 300 infective juveniles. On the other hand, S. carpocapsae (All) gave 100% mortality 120, 90, and 56 h post-treatment, respectively. Therefore, H. bacteriophora was more potent against cotton leafworm than S. carpocapsae. Studies on the infestation intensity of the nematode species against the cotton leafworm showed the predominance of H. bacteriophora over S. carpocapsae, while in studies of the reproductive rate those of S. carpocapsae predominate. The bacterial symbionts of each nematode species were isolated and tested alone against cotton leafworm at concentrations
ranging between 1×102 and 5×103 bacterial cells/larva. The results showed a higher activity of Photorhabdus luminescens than that of Xenorhabdu
nematophilus. |
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| Keywords: | Cotton leafworm Entomopathogenic nematodes Bacterial symbionts Infestation intensity Production rate |
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