Abstract:

 To establish the basis for identifying and synthesizing the sex pheromone of Holcocerus vicarius (Walker), the eclosion, mating and oviposition of H. vicarius adults were studied by means of observations and experiments both in the fields and laboratory. The circadian rhythm of sex pheromone production and release of H. vicarius was studied by means of electroantennogram (EAG) response. The results showed that the eclosion of H. vicarius happened throughout the day, especially from 15:00 to 19:00. Mating behavior started on the 1st night after the eclosion and the nuptial flight and mating took place from 21:30 to 0:30. The peak of mating occurred at 23:00 or so. The mating behavior was not observed during the photophase. Calling varied with the age of female, with older (2 to 3-day-old) virgin females calling earlier and for longer duration than younger (1-day-old) females. They had shorter time of mating when they were young. Females became sex mature one day later. The percentage of mating of 2-day-old was the highest (41.8%). The females searched the gap with ovipositor, and then began to oviposit. They oviposited at various places. The maximum of oviposition was up to 720 eggs, and the minimum was 105 eggs. The egg stage lasted 12-22 d. The hatch rate was from 72% to 88%. The amount of pheromone in the gland was relatively low on the first night after the eclosion, with a peak during the second night, and then decreased gradually when they aged. The amount of pheromone of 2-day-old virgin females began to increase gradually post 17:00, with the peak between 21:30 and 22:00, and then decreased gradually post 22:00. EAG response was the greatest at 22:30. The peak of sex pheromone production and release of H. vicarius occurred between 21:30 and 23:00. There was a circadian rhythm in the eclosion and mating of adults. The sex pheromone release and mating behavior of H. vicarius were synchronized, which was confirmed by tests of using virgin females to trap males in the fields.

Key words: Holcocerus vicarius, reproductive behavior, eclosion, mating, sex pheromone, circadian rhythm