OVIPOSITOR STEERING MECHANISMS IN PARASITIC WASPS OF THE FAMILIES GASTERUPTIIDAE AND AULACIDAE (HYMENOPTERA)

Similar but distinct ovipositor steering mechanisms in members of the parasitic wasp families Gasteruptiidae and Aulacidae are described. In both of these there are abrupt stops near the apex of each of the upp er and lower ovipositor valves. These stops, which are closely apposed when the ovipositor is at rest, prevent the lower valves from being e xtended posteriorly relative to the upper valve. Attempts to extend th e lower valves posteriorly force the ovipositor to bend dorsally. This ability to manipulate the ovipositor tip allows the wasps to locate t heir eggs more precisely in or near their hosts. In the Gasteruptiidae the stops are opposed, raised bosses which project laterally from the main ovipositor shaft. This mechanism is clearly visible externally i n intact ovipositors. In the Aulacidae, the pre-apical stops are forme d by the abrupt termination of a longitudinal ridge on each lower valv e and of grooves on the upper valve, The ridges run within the grooves and the mechanism is not visible externally. The implications of thes e mechanisms for the classification of these two families are discusse d.