אסיף מאגר המחקר החקלאי

Factors Affecting the Fluctuations in the Population of Toxoptera aurantii Boy. in Palestine

Year:

1938

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Volume :

25

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Abstract:

 

1. The Citrus aphis reproduces parthenogenetically continuously throughout the year; sexual reproduction has not been observed.

2. The most favourable temperature for development and reproduction of the aphis is between 22 and 25° C. Between 18 and 22° C. the rate of reproduction and development is also suflicient to bring about heavy infestation.

3. The temperature below 18° C. is unfavourable for considerable increase of the population of this hisect. At 7° C. reproduction is barely taking place.

4. At 30–32° C. the mortality of the nymphs is almost 100%. At 34–35° C. reproduction ceases, and at 36° C. adult insects die within a short period.

5. The annual fluctuations of the population of the insect based on field observations are described.

6. Food as a factor in the increase of the population of the aphis is discussed.

7. The effect of the annual fluctuations of the temperature in Palestine upon the population of the aphis is pointed out.

8. The economic status of the insect is discussed.

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