Abstract
Aim:
To evaluate the comparative parasitic efficiency and biology of
Trichogrammatid wasps on noble laboratory host Corcyra cephalonica as
well as on Helicoverpa armigera, the cosmopolitan, polyphagous and
precarious insect pest of many cultivated crops.
Methodology: The biology of Trichogramma chilonis and T.
japonicum, their sex ratio, and parasitic efficiency were studied. Host
insects were reared on artificial diet to obtain their eggs for initiating
the experiment. Egg-card pieces were prepared with the irradiated eggs of
respective host insects. Egg-cards were introduced into the tubes containing
freshly emerged adult parasitoids. Parasitized egg-cards (Trichocards) were
kept separately in plastic tube to study the biological attributes and
percent parasitization of the parasitoids. Egg cards of different host eggs
taking eggs of different age groups were prepared to study the effect of age
of host eggs on the biological efficiency of the parasitoids.
Results:
Irrespective of Trichogramma species, the duration (d) of eggs to
adult period was more when reared on the eggs of H. armigera than on
the eggs of C. cephalonica. Maximum life stage duration of T.
chilonis and T. japonicum from egg to adult was 8.2 days and 10.2
days, respectively, when reared on H. armigera eggs. There was maximum
parasitization (84.8%) of fresh eggs of C. cephalonica by T.
chilonis as compared to the egg parasitization of 73.4% by T.
japonicum. Likewise, extreme parasitization of fresh eggs of H. armigera
was recorded as 62.4% when parasitized by T. chilonisas against 59.7%
parasitization by T. japonicum.
Interpretation: According to the
study, H. armigera eggs have the finest biological and parasitic
features in terms of the highest adult longevity, sex ratio, mean progeny
female-1, and mean adult egg-1, making them the best
for mass production of the egg parasitoids, T. chilonis.
Key words: Corcyra cephalonica, Host eggs,
Helicoverpa armigera, Parasitization, Trichogramma
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