| dc.description.abstract | This project focused on improving the in vitro rearing methods of Toxoneuron
nigriceps, an important biological control agent of Heliothis virescens, by supplementing
the rearing media with the host hemolymph. T. nigriceps larvae of different ages were
incubated in the artificial rearing media. The growth (increase in length and width),
development (molting), and survival of the incubated larvae were observed. Changes in
osmotic pressure of the rearing media before and after incubation were evaluated. The
protein profiles of day 1, 3 and 5 hemolymph samples of the parasitized and
unparasitized H. virescens fifth instar larvae, used in the artificial rearing media, were
determined.
Host hemolymph improved the growth and development of T. nigriceps larvae in
the artificial rearing media except in the case of new and early first instar larvae.
Osmotic pressure of all media showed a significant decrease after the incubation of the
larvae except media incubated with the new first instar larvae indicating that the older
larvae absorbed and utilized more of the nutrients from the rearing media than the
younger larvae. Growth and development was higher in the semisolid media than in the
liquid media. In the artificial rearing media, the late first instar T. nigriceps larvae
molted to second instars and a few of them molted to third instars. The early and late
second instar larvae incubated in the artificial media also grew well and molted to third
instars. Some of the in vitro reared third instar larvae demonstrated behavioral changes
that could be expressed as the preparation for cocoon formation or pupation, however
neither a cocoon nor pupation occurred.
No qualitative differences in the protein titers were detected between hemolymph
of the parasitized and unparasitized fifth instar H. virescens larvae. There was a
significant increase in the protein concentration in both unparasitized and parasitized H.
virescens larvae as the age increased. This increase in the protein concentration showed
a positive effect on the growth and development of T. nigriceps larvae indicating that
availability of nutrients was an important factor for the growth of T. nigriceps larvae
in vitro. | en |
