DIGITALNA ARHIVA ŠUMARSKOG LISTA
prilagođeno pretraživanje po punom tekstu



ŠUMARSKI LIST 9-10/1965 str. 12     <-- 12 -->        PDF

7. Sid or, C. ((1959): Susceptibility of larvae of the large white butterfly (Pieris
brassicae L.) to two virus diseases. Ann. Appl. Biol. 47, 109—113.
8. S m i t h, K. M. and X e r o s, N. (1953): Cross inoculation studies with polyhedral
viruses. Symp. Intern. Roma.
COMPARATIVE INVESTIGATIONS INTO SUSCEPTIBILITY OF THE
CATTERPILI.ARS OF PROCESSIONARY MOTH (THAUMETOPOEA PITYOCAMPA
SCHIFF.) TO THE SPECIFIC POLYHEDRAL VIRUS DISEASE AND THE
VIRUSES FROM CERTAIN OTHER INSECT SPECIES


Summary


Through laboratory experiments it was established that the larvae of T. pityocampa
are susceptible to the cytoplasmic polyhedrosis of the Arctia caja larvae.
Cytoplasmic polyhedra obtained from naturally infected T. pityocampa larvae are
pathogenic for the larvae of A. caja. When older larvae of A. caja and T. pityocampa
were fed with polyhedra a number of them survived and produced imagos which
were abnormal and full of polyhedra. These polyhedra were found to be pathogenic
for the larvae of both species. The abnormal imagos did not copulate, but the perfect
moths which survived laid fertile eggs which produced larvae infected with polyhedrosis.
T. pityocampa moths could not be induced to lay eggs in captivity, and it was
therefore not possible to see if the virus was transmitted to the offspring.


Younger T. pityocampa larvae are more susceptible than older larvae to both
its own and to ihe A. caja polyhedral virus diseases. A four-year-old suspension of
the polyhedra of A. caja larvae did not lose its pathogenicity for T. pityocampa larvae.


Laboratory findings to the effect, that the cytoplasmic polyhedra of A. caja and


T. pityocampa larvae are pathogenic for T. pityocampa larvae was confirmed by
experiments in the forest. It was found possible to control this pest by applying a
suspension of polyhedra to infected Pine trees when the larvae were in the third
instar. 23—45"/o of the larvae were killed within two months, and those which were
still alive at that time were infected with the disease and were no longer taking food.
Older larvae on the control trees left unsprayed were healthy, and they caused
severe defoliation. The cytoplasmic polyhedra of A. caja are equally effective as the
specific polyhedra of T. pityocampa in controlling T. pityocampa larvae, and are
easier to produce.A. caja can be bred under laboratory conditions troughout the year,
while this is not possible with T. pityocampa, and although the A. caja larvae are
hairy, they do not cause any severe irritation associated with the handling of


T.
pityocampa.
At the time of spraying colonies of Diprion pini L. (Pine Sawfly) larvae were
noticed to feed on foliage. These larvae were unaffected by their feeding on needles
contaminated with the polyhedra of T. pityocampa and A. caja. The larvae of Melanostoma
mellinum L. (Syrphidac), which were feeding on T. pityocampa larvae diseased
with polyhedrosis pupated and gave imagos.