A Preliminary survey of domiciliary cockroaches and their oothecal parasites in Sri Lanka

Abstract

A survey of domiciliary cockroaches and their oothecal parasites was carriedout in 17 districts. The study was based on empty and live cockroach oothecaecollected from dwelling houses. Five species of cockroaches; Periplanetaamericana (L.) Neostylopyga rhombifolia (Stoll) Periplaneta australasiae (F.)Supella longfpalpa (F.) and Blatella germanica (L.) were found frequentinghouses. Of them, P. american a was the most abundant and widely distributedspecies, while B. germanlca was the least abundant species. P. americana andN. rhombifolia were present in all but one district, while P. australaslae and S.longipalpa were confined to 12 and 08 districts respectively. Mannar districtwas peculiar in that only one domiciliary species, N. rhombifolia was recordedfrom there. Only two species of oothecal parasites, Tetrastlchus hagenowli(Ratz.) and Evania appendlgaster (L.) were encountered during the study. Eachof these parasite species was characterized by the size of the emergence hole theymade in cockroach oothecae. Thus on the basis of the emergence hole alone itwas possible to categorize the empty oothecae as being parasitized. Of theoothecae, those of P. americana and P. australiasae were parasitized by bothspecies of parasites, while oothecae of N. rhombifolla was parasitized by T.hagenowii only. Oothecae of S. longipalpa and B. germanica were not parasitiizedat all. There appears to be a great paucity in the oothecal parasite fauna ofSri Lanka, compared to India where eight species of hymenopterans are known toparasitize oothecae of domiciliary cockroaches. The possibility of controllinghousehold cockroaches using local and introduced parasites remains to be explored.The shortcomings in this preliminary survey are also reported.