Flight Thresholds of the Armyworm (Lepidoptera: Noctuidae)

Abstract

Flight initiation threshold temperatures for agitated and undisturbed adult armyworms, Pseudaletia unipuncta, were measured. A predefined sequence of disturbances was applied to individual moths in an empty environmental chamber at various constant temperatures. With this agitation, the minimum flight threshold observed was 4°C, and the majority of moths could initiate flight at 10°C or above. A linear trend was noted between the log of duration of preflight wing shivering and ambient temperature. There were no detectable interactions with the sex or age of moths. Undisturbed moths were placed on oat seedlings at various constant temperatures under the photoperiodic conditions of rearing and left overnight. The presence of wing scales on a surface coated with Tanglefoot indicated flight. Flight was indicated at a minimum of 8°C. Flight maintenance thresholds were determined by lowering the temperature in a small tubular enclosure containing a single flying moth. Thresholds averaged 5.0°C for females and 3.9°C for males, with a minimum observed threshold of −l°C. No significant interactions with moth age or relative humidity at testing were noted.