Effect of Individual and Combined Treatment with Azadirachtin and Spodoptera littoralis Multicapsid Nucleopolyhedrovirus (SpliMNPV, Baculoviridae) on the Egyptian Cotton Leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)
El-Sayed H. Shaurub*, Afaf Abd El-Meguid, Nahla M. Abd El-Aziz
Abstract. The tetranortriterpenoid, azadirachtin, and the entomopathogenic virus, nucleopolyhedrovirus, are used as safe and new control measures for combating agricultural insect pests instead of the use of synthetic insecticides. They can be mixed together as an integrated pest management strategy. Thus, the current investigation was designed to determine the mortality, duration and weight gain of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) larvae, and the yield of Spodoptera littoralis multicapsid nucleopolyhedrovirus (SpliMNPV) (Baculoviridae) when the fourth larval instars were treated individually with the LC50 of azadirachtin and of SpliMNPV, and in combination with each other using the LC25, compared to non-treated larvae (control). The results obtained showed that combined treatment significantly enhanced the larval mortality by about 58.40 %, i.e. potentiation. Both individual and combined treatment significantly decreased the larval weight gain, whereas the larval duration was significantly increased, with the highest change in case of combined treatment. Azadirachtin–NPV mixture significantly decreased the viral yield (number of polyhedral inclusion bodies/g fresh larval body weight) by about 36.05 % compared to the individual treatment with the NPV. It can be concluded that although azadirachtin enhanced the pathogenicity (% larval kill) of SpliMNPV to S. littoralis, azadirachtin– SpliMNPV mixture is unlikely to be useful for the mass production of this viral isolate. Thus, these laboratory observations require validation in field studies under commercial growing conditions.
Key words: Spodoptera littoralis, azadirachtin, duration, weight gain, mortality, nucleopolyhedroviruses, viral yield.
Article № eb.14121, ICID: 1140472 [Full text - PDF]