Comparison of Bermudagrass lines grown in different cultural conditions and the effect on screening for fall armyworm (Lepidoptera: Noctuidae) resistance.

A study was conducted to investigate the effects of different cultural conditions on the quality of bermuda grass, Cynodon dactylon (L.) Pers., and its effect on the development and survival of the fall armyworm, Spodoptera frugiperda 0. E. Smith). Fall armyworm larvae were fed four bermuda grass lines, ‘Coastal,’ ‘Grazer,’ ‘Tifton 292,’ and OSU 71 × 6-7, grown under field and greenhouse conditions. Grasses grown in the field were less favorable for fall armyworm development and survival than the same lines grown in the greenhouse. Larvae fed bermuda grasses grown in the greenhouse had significantly higher larval and pupal weights and decreased duration for larval development. The quality of field-grown grasses, as indicated by crude protein, neutral detergent fiber, and in vitro digestible dry matter, was lower and declined more from June to September than the same grasses grown in the greenhouse. Larvae fed either greenhouse- or field-grown ‘Grazer’ generally developed faster than larvae reared on the other bermuda grass lines we evaluated. ‘Tifton 292’ appeared resistant to fall armyworm when grown under greenhouse conditions but did not always differ significantly from the susceptible line, ‘Grazer,’ when grown under field conditions. Greenhouse screening of bermuda grass for fall armyworm resistance should be confirmed with field evaluations.