Microbes Associated with Parthenogenesis in Wasps of the Genus Trichogramma

Cytological evidence is presented for a complete correlation between the presence of microorganisms in eggs and the incidence of revertible parthenogenesis (thelytoky) in wasps of the genus Trichogramma. A 2% lacmoid stain was used to visualize microorganisms in wasp eggs. Eggs of all 13 revertible parthenogenetic lines (i.e., lines that can be rendered bisexual by antibiotic treatment) carry microorganisms, while the eggs of all 5 nonrevertible parthenogenetic lines (i.e., lines that cannot be reverted to bisexual reproduction by either temperature or antibiotic treatment) are free of microorganisms. Microorganisms were not detected in eggs of 6 field-collected bisexual (arrhenotokous) lines, nor in those of 3 bisexual lines derived from revertible parthenogenetic lines by antibiotic treatment. The lacmoid stain provides a fast, easy method to detect microorganisms in the Trichogramma eggs and may be used in a modified form for the detection of microorganisms in the eggs of other species.