Ecological Studies on the Periplaneta Americana in Taipei

Author: Tuan-Sheng Miu, Shuenn-Lian Lee

Abstract：

1. In Taipei, the American cockroaches, Periplansia americans L. are usually found in dwellings, particularly in the kitchen, water closet and food store house, but scarcely in field.
2. The American cockroaches arc polyphagous insects. They feed on var-ious kinds of food including animal or vegetable diets. During the period of star-vation, they can maintain their longevity for a long time if water supplied only. Being highly adaptive to various environment, thus they can Iive in any circumstance and propagate generation to generation.
3. This insect has a strong negative phototropism. Daring the day or when the room is lighted, it always hides itself in the dark place. It habiturally stays upon the wall or perpendicular plane at rest.
4. No hibernation apparently takes place for this insect in Taipei, no consecutive physiological zero point appears in this area during the winter.
5. The lower fatal limit temperature of this insect is at 1-2° C in 12 hours for the first instar, 45 hours for the third instar, 65 hours for the old nymph and 70 hours for the adult. The unfavorable low temperature ranges from 3 to 17° C. while the unfavorable high temperature from 36 to 45° C. The higher fatal limit tempefattute is 49-50°C for the adult, 47-49° C. for the old nymth, 45.9° C. for the third instar, and 45.0° C for the first instar. The adult resistant to fatal high temperature seems to be greater than any other inatar; the former can remain a-live for 10% miniates in 49-50° C, whereas the latter, especially in the first in-star nymph, can only withstand for 5 minntes in the aarne degrees of temperature.
6. According to the present investigation, the temperature has a direct effect on the development of this insect. As shown in Table 4 and Fig. 2, the duration of egg stage ranges from 29 to 33 days at temperature of 30° C. but prolongs 57 to 67 days under the low temperature of 22-24° C, Therefore it seem reasonable to conclude that the higher the temperature, the shorter the duration of development in the egg stage within the range of effective temperature. Likewise the same conclusion may be drawn in the nyrnphal stage, for example, the nymph at the temperature of 30° C, may become adult only for 3 to 4 months, while at die temperature of 22-24° C the nymph has not as yet become adult though it has already been reared for more than 7 months.
7. The moisture may significantly effect the higher fatal limit temperature of the American cockroach. Under the saturated moisture condition, the higher fatal limit temperature of the adult is 52.5° G. and that of the old nymph is 50.4° C whereas under the dry condition that of the adult dropped to 45.1° C, and the old nymph to 43.4° C, This clearly indicates that the higher fatal limit temperature in the saturated moisture is 7-8° G higher than in the dry moisture.
8. The water content of the body and its excreta depends upon the air mois-ture. Under the saturated moisture environment, the water content of the body averages 63% and 67% in the old nymph and adult respectively; and the excreta always becmes fluidy, while in the dry environment, it decrease to 51% and 52% respectively, and the excreta dry and solid.
9. The changes of glycogen in the midgut between day and night is minor.

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