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 Peripianeta 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. hagenowii. 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.

Rastrococcus invadens Williams, a pest of fruit and ornamental trees in West Africa, was introduced from the Oriental Region. In 1986, a search was initiated in India for natural enemies of Rastrococcus spp. with a view to selecting potential biocontrol agents for introduction into West Africa. The results of the survey, laboratory breeding of the hosts and their natural enemies and host-specificity of the natural enemies are reported. Based on host-acceptance tests, two encyrtids, Gyranusoidea tebygi Noyes and Anagyrus sp., have been sent to UK for further screening.

In a survey for oothecal parasites of cockroaches in India, 6 species of cockroaches were recorded. Of these Neostylopyga rhombifolia (STOLE.) was restricted to thatched huts while Blattella germanica (L.), Periplaneta americana (L.), P. australasiae (F.), P. brunnea BURMEISTER and Supella longipalpa (F.) were common in other types of buildings. Eight species of parasites, of which 4 are new records; were reared: Anastatus tenuipes BOLIVAR., Cornperia merceti COMPERE, Evania appendigaster (L.), Evania sp. near antennalis WESTW., Genus et sp. nov. near Anastams. Tetrastichus asthenogmus (WATERSTON), T. hagenowii (RATZEr~URG) and Tetrastichus sp. (miser group) which is hyperparasitie. The natural and experimental hosts of these parasites are discussed. The low levels of field parasitism suggest there is scope for introducing more promising parasite species into India for biological control of cockroaches.

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Intra-and interspecific bisexual encounters between Bandicota bengalensis, Rattus rattus, Tatera indica and domesticated strain of Rattus norvegicus were staged for 10 min every day for seven days. The amicable, aggressive, submissive/ avoidance and residual behaviour counts were recorded for each partner of the different species combinations and compared. The different species pair combinations were classified as amicable, aggressive and neutral, depending on the ratios of aggressive and amicable behaviour counts. These results are discussed with reference to inter-species relationships, resident-intruder status, body weight-dorainance correlation, 'bully effect' of albino rats and sex differences in agonistic behaviour.