Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2012
Publication Date: October 1, 2012
Citation: Tofangsazi, N., Buss, E.A., Meagher Jr, R.L., Mascarin, G.M., Arthurs, S.P. 2012. Thermal requirements and development of Herpetogramma phaeopteralis (Lepidoptera:Crambidae:Spilomelinae).. Journal of Economic Entomology. 105(5):1573-1580.
Interpretive Summary: The tropical sod webworm (TSW) is a moth pest of turfgrasses in the southeastern United States. Caterpillars eat grass blades and form matting under the plants that make it difficult for insecticides to be effective. One management tactic that may be used in the future to reduce populations is host plant resistance. Breeding turfgrass varieties to be resistant to TSW will first involve laboratory bioassays that require large numbers of caterpillars. In this report, scientists at the University of Florida and the USDA, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, investigated several commercially-available diets and St. Augustinegrass for laboratory rearing of TSW. Caterpillars completed development on St. Augustinegrass at temperatures above 15°C but below 35°C. However, caterpillars were unable to complete development on any of the artificial diets. More research on what ingredients are needed in the artificial diet for this pest is ongoing.
The tropical sod webworm, Herpetogramma phaeopteralis Guenée is a major turfgrass pest in the southeastern United States. We evaluated larval development on five artificial diets and at six temperatures (15, 20, 25, 30, 32.5, 35 ±1 °C) on St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze]. Only individuals fed on St. Augustinegrass and soy-wheat germ diets were able to complete their lifecycles. None of artificial diets tested (corn-based, soy-wheat germ, corn cob-wheat germ, corn cob-soy flour, or Pinto bean) were suitable for rearing this species, due to high mortality and slower developmental time. The total developmental time (from oviposition to adult) on S. secundatum significantly decreased from 47.8 d at 20°C to 21.1 d at 30°C, and then increased to 32.6 d at 32.5°C. Tropical sod webworm failed to complete larval development at 15 and 35°C. The relationship between temperature and developmental rate was described using two linear (common and polynomial) and two nonlinear models (Briere-1 and Briere-2). The estimated lower temperature thresholds using a linear model for eggs, first, second, third, fourth, fifth, and sixth instars, prepupa, pupa and the total development were 10.1, 6.9, 12.3, 10.5, 15.3, 13.9, 9.1, 13.1, 12.0 and 13.1°C, and the thermal constant of these stages were 62.9, 66.2, 38.2, 40.3, 24.9, 32.3, 51.9, 106.4, 109.9 and 370.4 degree-days (DD), respectively. The Briere-1 model provided the best fit with estimated lower, upper and optimum thresholds for total development of 14.9, 34.3 and 29.4°C, respectively. The developmental requirements of H. phaeopteralis can be used to help predict the distribution and seasonal phenology of this pest.