Integration of leaf extracts from Helianthus annuus and varietal resistance in the control of Sitotroga cerealella (Lep.: Gelechiidae) infesting paddy rice

The bioactivity of leaf extracts of Helianthus annuus L. against Sitotroga cerealella (Olivier) in stored paddy rice varieties was evaluated in the laboratory of the Federal University of Technology, Akure, Nigeria at ambient temperature of ۲۸ ± ۲ °C and ۷۵ ± ۵% relative humidity. Standard methods were used to determine toxicity of the plant powders and extracts, to S. cerealella based on weight loss, adult emergence, adult mortality and developmental periods. Paddy rice from previously categorized susceptible and moderately susceptible varieties was used for the research work. The adult mortality was assessed at ۲۴, ۴۸ and ۷۲ hours of application. The solvent extracts of the plant significantly reduced or prevented adult emergence of S. cerealella. Also there was an increase in the developmental period (P > ۰.۰۵) and reduction or prevention of seed weight loss. Adult mortality of ۱۰۰% was observed in S. cerealella in paddy treated with ۴% petroleum ether leaf extract in FARO ۴۴ as compared with ۱۰۰% mortality in FARO ۵۲ paddy treated with ۳% petroleum ether leaf extract. Lowest adult moth mortality of ۳۰.۳۳% and ۳۵.۲۰% were observed in ۱% ethanolic leaf extract treated in FARO ۴۴ and FARO ۵۲ respectively. Results showed that H. annuus plant parts in combination with the susceptible paddy variety, FARO ۵۲ increased mortality of adult S. cerealella and prolonged developmental periods. Both the powder and the extracts of this plant could be produced on commercial scale and incorporated into pest management programmes.

کلیدواژه ها:

Helianthus annuus ، Sitotroga cerealella ، paddy rice varieties ، Susceptibility ، mortality