Stage-specific parasitism of Diadegma semiclausum：Consequence for the parasitoid and its host,Plutella zylostella
The Ichneumon wasp，Diadegma semiclausum，is an important larval-prepupal endoparasitoid of the dianaondback moth.Plutella xylostella.Parasitism of Plutella larvae of different instars and different developmental ages of the 4th instar of the pest and the consequences for both the parasitoid and the host were investigated at 24℃ in laboratory.Diadegma semiclausum preferred parasitizing host larvae in 2nd and 3rd instars over 4th instars.Parasitism decreased with increasing host age of the 4th instars.Development time，final aduIt size.adult fecundity and longevity of the parasitoid varied with the host instar at initial parasitization.Parasitoids with initial parasitism in the 4th instar host had the shortest development time，and had the largest bodv size，followed by those in the 3th instar，and then by those in the 2nd instar.Parasitoid females starting parasitism in 3rd instar host had the highest fecundity and the greatest longevity.However，the survival rate of the parasitoid during immature stages and the fecundity of the parasitoid adult female in the first day post-emergence did not vary with the host instar at initial parasitization.Parasitized host larvae exhibited longer development time compared with unparasitized ones，no matter when the larvae were parasitized initially. The host prepupae developed from parasitized larvae were not able to pupate，and the duration of the host staying in the prepupal stage increased with increase of host instar at parasitism. The parasitized larvae consumed similar amounts of cabbage leaf as the healthy larvae with the exception that parasitized larvae consumed significantly less cabbage leaf than healthy larvae during their 4th instar，when parasitism occurred at early 2nd instar.
Zhong-Ping Hao Zu-Hua Shi
Institute of Insect Sciences,Zhejiang University,Hangzhou 310029,China
国际会议
北京
英文
190-201
2006-10-24（万方平台首次上网日期，不代表论文的发表时间）