Slide mounting Techniques For Trichogramma (Trichogrammatidae) And Other Minute Parasitic Hymenoptera

Methods for preparing Canada balsam slides of Trichogramma and similarlysized parasitic Hymenoptera are presented.Included are procedures for transferring to balsam, specimens that were originally mounted in temporary, water soluble media, such as Hoyer's medium.The primary factor responsible for our poor understanding of the systematics of minute parasitic Hymenoptera such as the Trichogrammatidae is the absence of adequate study collections.Certainly this can be attributed, in part, to difficulty in collecting which usually involves searching for hosts, or, more commonly, carefully sorting through bulk collections such as Malaise trap or sweep samples.However, once specimens are found the problem of preparing them for study perhaps is even more daunting.For detailed study most parasitic Hymenoptera with a body length of 1 mm or less must be placed on slides.This includes species of Trichogramma and those of virtually all other trichogrammatid genera.Unfortunately, there has been a tradition of mounting such wasps in water soluble media such as Hoyer's (e.g.Rosen and Debach 1979) or Liquid Faure (e.g.Doutt and Viggiani 1968) which, unless carefully monitored, eventually dehydrate and damage specimens (Upton 1993).The argument against using temporary media for small chalcidoids has been well made by Noyes (1982).Additional problems with earlier collections of micro-Hymenoptera are that specimens frequently were mounted uncleared and in a lateral rather than dorsoventral position, both practices precluding adequate examination of important characters, particularly the male genitalia, which in the Trichogrammatidae are important for classification and often identification as well (Nagarkatti and Nagaraja 1971, Viggiani 1971).This paper presents the techniques developed over several years at the University of California, Riverside, primarily for preparing permanent Canada balsam mounts of Trichogramma.The methods also have been applied to other genera of Trichogrammatidae and are appropriate for other small, lightly-sclerotized wasps such as Aphelinidae.Because these groups are frequently placed in Hoyers we also describe our techniques for transferring such specimens to Canada balsam.Publication of these methods is motivated by the large number of lots of Trichogramma received from biological control workers for identification and !