• Korean journal of applied entomology
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• v.5_6
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• pp.39-46
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• 1968

This experiment was conducted to study the effects of nitrogen, phosphorus, potassium, and sugar contents in the loaves of five different host plants on tile larval period, pupal period, pupal period, number of eggs in the ovary, and the tolerance of fall webworm larvae (Hyphantria cunea DRURY) to gamma-BHC. The results obtained in this study were as follows; 1. The contents of nitrogen, phosphorus, potassium, and sugar in tile leaves tested were varied with the species of the host plants and sampling time. 2. The larval and pupal periods were also varied with the host plants and generation of the fall webworm. The shortest larval and pupal periods were found in the mulberry and the longest ones in the apple tree, and their periods were shortened much more in the second generation. Except the relation between the larval period and tile nitrogen content in the first generation, significant correlation could not be found between their periods and nitrogen, phosphorus, potassium and surgar contents. The nitrogen contents among the other chemical factors, however, might be much more influenced on their developing period. 3. The pupal weight and number of eggs in the ovary were also varied with the host plants. sex, and generation. In both generations, the greatest pupal weight and number of eggs per female were found in the mulberry and the least ones in the apple tree. No significant correlation could be found between the pupal weight and number of eggs per female and the chemical factors analyzed. However, only the nitrogen content seemed to be highly related to the pupal weight and number of eggs. 4. The tolerance of the fall webworm larval to gamma-BHC was highly varied with the host plants. The host order o( the larval tolerance level to gamma-BHC was box-elder, popla, platanus, apple tree, and mulberry. There was no significant correlation between the larval tolerance to the BHC and the chemical factors analyzed. However, the larvae fed on the host plant with higher pottassium content were shown a tendency to be higher tolerant.

• Korean journal of applied entomology
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• v.4
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• pp.59-64
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• 1965

This study was planned to find out the effects of several food-plants on the pupal weight and the number of eggs in the ovary of the fall webworm, Hyphantria cunea $D_{RURY}$. The larvae were separately reared on different food-plants in the Petri dish. Four to six day old pupae were used for the study of the pupal weight. The number of eggs in the ovary was counted under the binocular dissecting microscope. The loaves of the food-plants were sampled on Juiy 16, and analyzed by Kjeldahl method for the determination of total nitrogen content. The results obtained in this study were as follows; (1) The pupal weights were highly different according to the species of plants and sexes. The greatest pupal weight found in the pupae reared on the mulberry and the least one in the pupae reared on the apple tree. The weight female pupae was greater than that of male pupae in every case. (2) The number of eggs in the ovary was positively correlated to the pupal weight. (3) The nitrogen content of the food-plants used in this experiment was varied with the species of the plants. However, the nitrogen content of the food-plants was not significantly correlated to the pupal weight and the number eggs in the ovary.