The Biology of Trichoplusia ni (Lepidoptera: Noctuidae). IV. Environmental Control of Mating12

Abstract

Among adults of Trichoplusia ni (Hubner) exposed to naturally fluctuating environmental conditions, few matings occurred on nights when the midnight temperature was less than 14°C. In the laboratory, T. ni adults mated at temperatures as low as 10°C, after having been held for 4 days at 26±1°C. The threshold-temperature range for mating in the laboratory was similar to the threshold-temperature range for male responses to female sex pheromone extracts. Light influenced both the occurrence and the timing of mating. Mating was inhibited at light intensities greater than 0.3 lux. The mean time of mating in the field and in the laboratory was after midnight. Although the timing of mating was found to be influenced slightly by the circadian rhythm of responsiveness in the male, the timing was primarily controlled by a light: dark-cycle-entrained rhythm in the female.