This study aims to investigate the effectiveness of different
concentratiois of carbon dioxide in controlled (modified) atmospheres as well as
a controlled atmosphere of more than 99 % nitrogen in controlling the active
and diapausing larvae of the Khapra beetle. Trogoderma granarium (Everts) at
various temperatures. Results of the experiments conducted at 16, 21. 26 and
31°C and 55±5 % RH. in the laboratory using the following five controlled
(CA) atmospheres :
1- 96% CO2 : 3.2% N2 : 0.8% 02
2-68%C02 : 25.6 %N2 6,4%02
3-46 0/ CO2 : 43.2 % N2: 10.8 0/ 02
4-23 % CO2 : 61.6 % N2 + 15.4 % 02
5- CA of around 99.5 % N2 + 0.5 0/ 02
Showed the following : The exposure time required to obtain 99 % mortality at
16°C was 17, 34, 39, 75 and 8.1 days for the active larvae; and 25.6, 38, 46, 109
and 11.1 days for the diapausing larvae at the different aforementioned
atmospheres, respectively. Exposure periods needed lo achieve 99 % kill at
21°C were 13.9. 23.1. 48.5. 62.5 and 7.3 days for the active larvae; and 216,
29.8, 58.0, 61 .6 and 7.4 days for the diapause one at the various CA.
respectively.
Time recorded to achieve 99 % mortality at 26°C was 8.9, 16.5, 20.3,
36.7 and 5.7 days for the active larvae and 10.7, 24.0, 36.4, 47.1 and 5.9 days for
the diapausing larvae at the aforementioned CA, respectively. Exposure periods
needed for 99 % mortality at 31°C were 7:8, 10.8, 18.7, 22.7 and 4.2 days for the
active larvae: and 10.3, 20.1. 30.3, 42.0 and 5.7 days for the diapausing larvae at
the aforementioned five controlled atmospheres, respectively.
The results indicate clearly. that the diapausing larvae of T granariuin
were more tolerant to time various tested atmospheres than the actïve one at all
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