Environmental Entomology (1991) 20, 53-60

James E. Baker, Stanley M. Woo, James E. Throne and Patrick L. Finney (1991)
Correlation of alpha-amylase inhibitor content in eastern soft wheats with development parameters of the rice weevil (Coleoptera: Curculionidae)
Environmental Entomology 20 (1), 53-60
Abstract: The alpha-amylase inhibitor content in saline extracts of 104 Eastern soft wheat cultivars was determined by assay against a purified alpha-amylase preparation from the rice weevil, Sitophilus oryzae (L.). A two-fold range of inhibitor levels, expressed as amylase inhibitor units per gram of dry weight (AIU/g), was found across all cultivars. Inhibitory activity was lowest in cultivar 'Augusta' (5,084 ± 124 AIU/g) and highest in cultivar 'Logan' (110,410 ± 61 AIU/g). No correlation of inhibitor content with progeny production (r = -10.161) or rate of emergence (r = -0.292) was found among weevils reared on 30 cultivars having relatively low, medium, and high inhibitor levels, but there was a positive correlation between inhibitor content and average number of days to adult emergence (r = 0.569). Although mean development times were significantly different on cultivars with low and high AIU/g (35.9 ±.0.2 and 36.6 ± 0.1 d, respectively), the differences were only slight and indicated that, for these cultivars of soft wheats, alpha-amylase inhibitors have little practical effect on initial population reductions. Nevertheless, based on a population model for S. oryzae developing on wheat at 25°C and 75% RH, the slight delay in mean development time (0.7 d) on cultivars with relatively high AIU/g results in a 20.9% reduction in total number of weevils after 180 d. Simulations also indicate that physical or biochemical resistance factors in wheat have to delay development time for about 6.2 d or reduce fecundity by about 40% to prevent wheat from being graded 'weevily' 180 d after a single pair of weevils infests a hypothetical 6,000-bushel wheat bin.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): James E. Throne

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Sitophilus oryzae	Stored grain