Date of Award

4-2016

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Entomology

First Advisor

Brandon Schemerhorn

Second Advisor

Jeffrey Holland

Committee Chair

Brandon Schemerhorn

Committee Co-Chair

Jeffrey Holland

Committee Member 1

Jeff Stuart

Abstract

The effects of Hessian fly (Mayetiola destructor Say) infestation on the putative tolerant wheat line Pioneer ®brand variety 25R78 were investigated at the seedling stage. Measurements, including leaf and tiller number, leaf growth rate, and total leaf lengths were recorded for two time intervals, 16 and 32 days post infestation (dpi). At 16 dpi, total leaf length changes and leaf growth rates were significantly lower for infested tolerant plants versus uninfested plants. No permanent growth effects occurred in the 32-day set. There were no significant differences in change in leaf length and leaf growth rate in infested tolerant plants compared to uninfested plants. Infested tolerant plants exhibited significantly higher leaf numbers per plant, but no significant difference in tiller numbers compared to uninfested plants. No dead red larvae were observed, differing from resistant plants commonly used and preventing selection pressure on fly populations.

Tolerant plants showed no significant effects on leaf or tiller number, total leaf length, or leaf growth rate due to infestation. The larvae observed on the tolerant plants were smaller compared to larvae on susceptible lines ‘Newton’ and Pioneer variety 25R75 with no significant difference from larvae on ‘Iris’ plants. Additionally, tolerant plants had significantly more visible larvae with greater distances of visible larvae from the soil and from the first ligule and were the only plants with visible larvae above the first ligule. Tolerant plants showed no effect from infestation on head or tiller number, total seed number and weight, average seed number and weight, head height, head length, and other measurements. This was comparable to the infested resistant line, Pioneer® brand variety 25R32.

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