The bioecology and larval population fluctuation of Danaus chrysippus linnaeus (Lep.: Nymphalidae) in Bushehr, Iran.

Danaus chrysippus L. (Lep.: Nymphalidae) is the most important pest on Calotropis procera Aiton in Bushehr-Iran. The larvae make the main damage by feeding on leaves and shrubs. The purpose of this project was the study of bioecology and larval population fluctuation of D.chrysippus, carried out between 2006 and 2007 in Saadabad area in Bushehr-Iran. The sampling was carried out weekly by a two stage cluster sampling method in nature. For the biology studies, the eggs were collected from the nature and were developed in petri dishes and 10×12 plastic dishes from egg to adult under laboratory conditions at 25±2 ºC and 22±2 ºC, %60±10 RH and 16/8 L:D. The results showed that the first adults emerged and gradually laid eggs in February 2006. The peak of larval population was observed in 2nd and 3rd weeks in March then reduced gradually. The egg laying was observed in the first week of April. The larval population peaks were in the middle of April, the 2nd and 3rd weeks of May, the last week of June and in July. During the summer and the winter of 2007, no forms of this butterfly was observed in Saadabad. The total period from egg to adult was 37.08± 0.5 and 26.07± 0.8 days at 22 ºC and 25 ºC respectively, in laboratory conditions. This butterfly had 5 generations a year. The generations overlap was observed. In the summer, the butterfly migrated to Bushehr mountains near the Fars province. In the winter, D.chrysippus migrated to coastal lines near the Hormozgan province.