Effect of Some Environmental Factors on the Toxicity of Azadirachtin to the Egyptian Cotton Leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)
El-Sayed H. Shaurub*, Afaf Abd El-Meguid, Nahla M. Abd El-Aziz
Abstract. Although the bio-degradation of azadirachtin was well studied under storage or environmental conditions, its toxicity was not characterized so far under the impact of environmental conditions. Therefore, the present study aims to elucidate the toxicity of azadirachtin, at the level of LC50, to the fourth larval instars of Spodoptera littoralis (Boisduval) under the stress of temperature, ultraviolet radiation (365 nm) (UV-A) and of artificial sunlight. The increase in post-treatment temperatures insignificantly affected azadirachtin toxicity. Likewise, insignificant change was also attained for the increase in the exposure periods of both UV and sunlight, except for exposure to sunlight without UV filter starting from 10 h, where the toxicity of azadirachtin was significantly declined. It can be concluded that azadirachtin toxicity will last efficiently against S. littoralis larvae under the stress of the environmental factors prevailing during the season of cotton cultivation in Egypt.
Key words: Azadirachtin, Spodoptera littoralis, sunlight, temperature, toxicity, ultraviolet.
Article № eb.14204, ICID: 1140476 [Full text - PDF]