The effect of some plant inhibitors on biological traits and digestive physiology of Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae)

Borzouei, Ehsan and Naseri, Bahram and Nouri Ghanbalani, Ghadir (2017) The effect of some plant inhibitors on biological traits and digestive physiology of Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae). Doctoral thesis, University of Mohaghegh Ardabili.

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Text (تأثیر برخی مهارکننده‌های گیاهی بر ویژگی‌های زیستی و فیزیولوژی گوارشی Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae)) Ehsan Borzouei.pdf Download (1MB) | Preview

Abstract

The present survey is including two experiments. In first experiment, biology and physiological traits of Sitotroga cerealella (Olivier; Lep.: Gelechiidae), a world-wide insect pest of cereals, were investigated on different grains including barley, maize, rye, sorghum, triticale, and wheat. Larval and pupal duration was the shortest on wheat and triticale, and the longest on sorghum. There were significant differences in survival rate of immature stages on different grains. The highest realized fecundity and egg fertility was observed on triticale and the lowest was seen on sorghum. Larvae fed on triticale and wheat showed higher amount of α-amylase activity than those fed on other grains. Maximum Vmax/KM ratio was determined for the midgut α-amylase of S. cerealella larvae fed on wheat. Whole-body protein, lipid, and glycogen contents of pupae reared on sorghum and rye were significantly lower than those reared on other grains. The statistical analysis showed that the clear correlation could be drawn between the biological characteristics and energy contents of S. cerealella on one side and seed hardness, amylolytic activity, and food consumed on the other. According to the findings of this study, the variable responses of S. cerealella to feeding on different host grains could be attributed to the quality of diets tested. In this experiment, wheat was selected as more suitable host and used for subsequent experiments. In second experiment, the inhibitory effects of Avena sativa L. seed extract were studied on life history and some physiological aspects of S. cerealella. The results of α-amylase inhibition in vitro by A. sativa proteinaceous extract suggested its potential effect on S. cerealella larvae. Although, chronic ingestion of A. sativa inhibitor (I10) 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 I30 and I50 concentrations of the inhibitor. The highest and lowest realized fecundity was recorded for females fed on I10 and I50 concentrations, respectively. The lightest weight of pupae of S. cerealella was observed on I50 concentration. The lowest glycogen and lipid contents of the pupae were detected on I50 concentration. The lower survival rate of pupae at sub-zero temperature indicated that S. cerealella fed on I50 concentration of the inhibitor was less cold tolerant than control insects. The inhibitory studies indicated that A. sativa proteinaceous extract had high inhibitory activity for the α-amylase of this pest. This inhibitor can be expressed in genetically engineered plants to confer resistance of grains to S. cerealella.

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