Abstract:
A survey of domiciliary cockroaches and their oothecal parasites was carried
out in 17 districts. The study was based on empty and live cockroach oothecae
collected from dwelling houses. Five species of cockroaches; Periplaneta
americana (L.) Neostylopyga rhombifolia (Stoll) Periplaneta australasiae (F.)
Supella longfpalpa (F.) and Blatella germanica (L.) were found frequenting
houses. Of them, P. american a was the most abundant and widely distributed
species, while B. germanlca was the least abundant species. P. americana and
N. rhombifolia were present in all but one district, while P. australaslae and S.
longipalpa were confined to 12 and 08 districts respectively. Mannar district
was peculiar in that only one domiciliary species, N. rhombifolia was recorded
from there. Only two species of oothecal parasites, Tetrastlchus hagenowli
(Ratz.) and Evania appendlgaster (L.) were encountered during the study. Each
of these parasite species was characterized by the size of the emergence hole they
made in cockroach oothecae. Thus on the basis of the emergence hole alone it
was possible to categorize the empty oothecae as being parasitized. Of the
oothecae, those of P. americana and P. australiasae were parasitized by both
species of parasites, while oothecae of N. rhombifolla was parasitized by T.
hagenowii only. Oothecae of S. longipalpa and B. germanica were not parasitiized
at all. There appears to be a great paucity in the oothecal parasite fauna of
Sri Lanka, compared to India where eight species of hymenopterans are known to
parasitize oothecae of domiciliary cockroaches. The possibility of controlling
household cockroaches using local and introduced parasites remains to be explored.
The shortcomings in this preliminary survey are also reported.
