|Wright, Maureen - UNIV OF MISSOURI|
|Brandt, Sandra - UNIV OF MISSOURI|
Submitted to: Annual Meeting Central States Entomological Society
Publication Type: Abstract Only
Publication Acceptance Date: April 27, 1995
Publication Date: N/A
Technical Abstract: The venom of the ectoparasitoid Euplectrus comstockii (Hymenoptera: Eulophidae) causes arrestment of larval-larval ecdysis after injection by the wasp into the hemocoel of its hosts. The hemolymph of the host is believed to aid in the delivery of the venom to its target tissues. Determining the temporal stability of the arrestment activity in the venom within its host is a key step towards understanding the mechanism of actio of the venom. Hemolymph from parasitized 3rd instar Trichoplusia ni larvae arrests ecdysis when injected into 4th instar larvae. However, arrestment activity within the hemolymph decreases from 90% to < 5% within 12 hours post-parasitism, while purified venom stored in a phosphate buffer solution retains 100% of the arrestment activity over this time period. Protease degradation of the venom within the hemolymph may account for part of this inactivation since insect hemolymph has been shown to contain proteolytic activity and the arrestment activity within the venom is susceptible to inactivation by protease K. These experiments suggest that the venom component responsible for arresting larval-larval ecdysis acts on its target tissue within at least 12 hours of parasitism. The progressive decrease in the amount of arrestment activity recovered from the hemolymph of a parasitized host over time suggests that the venom is slowly inactivated within the hemolymph or is removed from the hemolymph via uptake by target tissues.