Abstract:
The rice leaf folder, (RLF) Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)
is one of the pests attacking rice foliage. Defoliation damage caused by RLF
larvae demands the implementation of control measures, usually the application
of insecticides. This practice results the disturbances to the colonizing natural
enemies in rice ecosystem. Hence, use of non-chemical strategies to manage
RLF will enhance the colonization of natural enemy community in rice
ecosystem. Therefore, biological control of RLF was suggested using egg
parasitoids. As a first step of this endeavour, identification of naturally existing
egg parasitoids is necessary. The objective of this study was to identify the egg
parasitoids of RLF in rice ecosystem. The eggs of RLF were collected at weekly
intervals over different durations in thirteen selected rice fields in Kandy,
Anuradhapura and Kurunegala districts. The collected eggs were reared
individually until emergence of parasitoid adult or the host larvae in clear plastic
vials under laboratory conditions. The emerged parasitoid adults were dissected
and slide mounted for microscopic examination to identify the species using
taxonomic keys. The identities were verified by Natural History Museum,
London. Two species of Trichogrammatidae parasitoids were found parasitizing
the eggs of RLF: Trichogrammatoidea bactrae Nagaraja, T. nana Zehntner.
Both species were not reported in Sri Lanka as per the Universal Chalcidoidea
database, NHM, London. Characteristics of genitalia of both species well match
with the original species description. T. bactrae was found in
Megodakalugamuwa, Hindagala, Ihalawela, Penideniya, Ganegoda and
Wathurakumbura (Kandy district) and Mahailluppallama (Anuradhapura
District). T. nana was found only in Penideniya (Kandy district).
