Tetrastichus hagenowii (Ratz.) and T. asthenogmus (Wtstn.) are parasitic in cockroach oothecae and may themselves be attacked by a species of Tetrastichus of the group of T. miser (Nees). In Bangalore in 1976–79, the primary parasites were reared from oothecae of Periplaneta americana (L.), P. australasiae (F.) and P. brunnea Burm., and laboratory colonies of them were established on oothecae of P. americana. The hyperparasite, reared from field-collected oothecae of Periplaneta spp., was bred in the laboratory on oothecae of P. americana containing larvae of T. hagenowü. The immature stages of the three species of parasites were compared and their biologies studied. The eggs of the three species can be differentiated on the basis of their shape as can the pupae, but the larvae of the two primary parasites are indistinguishable. The duration of the developmental stages of the three species overlapped but the hyperparasite had a slightly shorter pupal period. Host finding by the T. hagenowii female was investigated. The two primary parasites were similar in most of their biological attributes. However, T. asthenogmus was inherently superior to the Bangalore strain of T. hagenowii in having lower levels of female sterility and its greater preference for the oothecae of P. brunnea, the predominant species of cockroach in Bangalore. T. hagenowii proved to be more tolerent of low temperatures than T. asthenogmus. The hyperparasite had an advantage over the other two species in possessing longer life-span and synovigenic females, and individual females parasitised more oothecae in their life-span than the primary parasites; but it was unable to distinguish healthy oothecae from those containing larvae of the other two species until it had drilled into them.
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