In Vitro and In Vivo Effects of α-Amylase Inhibitor From Avena sativa Seeds on Life History and Physiological Characteristics of Sitotroga cerealella (Lepidoptera: Gelechiidae)

The inhibitory effects of Avena sativa L. seed extract were studied on life history and some physiological aspects of Sitotroga cerealella (Olivier; Lepidoptera: Gelechiidae). The inhibition of α-amylase activity in vitro by A. sativa proteinaceous extract suggested its potential antimetabolic effect on S. cerealella larvae. Although, chronic ingestion of A. sativa inhibitor (I(10): 0.108 mg protein/artificial seed) did not show significant reduction of the growth and development of S. cerealella. However, a delay in the developmental time of immature stages was detected when S. cerealella larvae were continuously fed on I(30) and I(50) concentrations (0.429 and 1.11 mg protein/artificial seed, respectively) of the inhibitor. The highest realized fecundity was recorded for females which came from larvae fed on I(10) concentration (102.46 ± 2.50 eggs/female), and the lowest fecundity was observed for females which came from larvae fed on I(50) concentration (31.64 ± 3.17 eggs/female). The lightest weight of pupae of S. cerealella was observed on I(50) concentration (2.76 ± 0.07 mg). The lowest glycogen and lipid contents of the pupae were detected on I(50) concentration (50.00 ± 3.53 and 289.57 ± 29.00 µg/pupa, respectively). The lower survival rate of pupae at low temperature indicated that S. cerealella fed on I(50) concentration of the inhibitor was less cold tolerant than control insects. The inhibitory studies indicated that A. sativa proteinaceous extract is a good candidate as an inhibitor of the α-amylase of this pest. This inhibitor can be expressed in genetically engineered plants to confer resistance to S. cerealella.