| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1989: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1988: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Species composition and parasitism of hymenopterous egg parasites of the pine moth, Dendrolimus spectabilis Butler were studied from 1988 to 1990 in the coastal areas of Kashima-Gun, Ibaraki Prefecture.
Total parasitism by three species of egg parasites, Telenomus dendrolimi (Matsumura), Anastatus japonicus Ashmead and Trichogramma dendrolimi Matsumura, was generally lower than 30% though it reached to over 40% at some study plots. This tendency was the same as the results from the field surveys done in the recent ten-odd years.
Among parasites, Anastatus showed the highest parasitism in the northern study plots, while Trichogramma did the highest one in the southern ones, indicating that parasitism of Telenomus was the lowest through all study plots which are scattered from south to north extending over 30km though it often became higher soon after the second emergence of host eggs occurred.
Recovering the second emergence of host eggs was tried by releasing larvae and pupae of the pine moth, and response of parasites to host eggs originated from them was observed. The emergence rate of host egg masses (No. of egg mass / No. of released) was lower than 10%, suggesting that birds preyed on much of the hosts released. Parasitism of Telenomus to host eggs of the artificial population was usually higher than that to ones of the natural populaton, but Anastatus and Trichogramma showed no different parasitism between both populations.
It is concluded that parasitism of Telenomus tends to be higher rapidly in accordance with the increase of emergence frequency of host eggs probably because this parasite is dependent strongly on the pine moth population of this district for its propagation.
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