الفهرس 
Materials and mithodsOnly 14 pages are availabe for public view
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Abstract
The main objective of the present work was to study the development of resistance in the red flour beetle (Tribolium castancum
Herbst) to phosphine, carbon dioxide and their mixture. Also to investigate
some biological characteristics of the resistant strain to a combination of
phosphine plus carbon dioxide in comparison to the parental stock.
This work was conducted at the Plant Protection Dept., Faculty of
Agriculture at Moshtohor, Zagazig University. Data obtained could be summarized as follows : 1- Development of resistance in T castancum - adults to phosphine, carbon dioxide and a combination of the two gases:
Adult populations of ’Lcastancum were exposed in the laboratory for 16 generations to a fixed concentration of 40 vpm phosphine (56.52 /.l
gil) a controlled atmosphere containing 46% carbon dioxide and a
combination of 40 vpm PH3 + 46% CO2 at varying exposure periods, 26 ±
1°C and 6 ± 1°C,.in order to select strains resistant to phosphine, carbon
dioxide and their mixture. Selection pressure was carried out at the median
lethal dose/time inducing mortalities ranged from 50-70%. I.I-Development of resistance in T.castaneum adults to
phosphine, Results indicated, that the lethal time values (LT50 LT 90, LT99)
were significantly higher at the lower temperature 6 ± 1°C than at the
higher one (26 ± 1°C) and at the 16th generation, the lethal times needed
for a certain kill were markedly longer for the phosphine resistant strain
than the laboratory strain.
Results of selection indicated that T castancum adults have the
genetic potential to develop resistance to phosphine and the treatment of
the successive generations of this insect with the median lethal dosages of
phosphine produced insects with increased tolerance to the fumigant at the two test temperatures. The adults of the 16th generations showed 15.J-fold
resistance to phosphine at 26 ± 1°C and 10.2 - fold resistance at 6 ± 1°C
when compared with the laboratory stock at the LT50 - level.1.2 - Development of resistance in T.castaneum to carbon
dioxide : Results indicated that at the 16th generation. the lethal time values
achieved for certain mortality were significantly higher at the two test
temperatures, when compared with the laboratory strain. The adults of the 16th generation showed at 26 ± IOC 1.8 and 1.9 fold at LT50 and LT90 - level. respectively. At 6 ± 1°C the 16th generation revealed 1.7 and 1.8 fold at LT50 and LT90 -level, respectively.
This result indicated that T.castaneum adults was capable to develop low resistance to an atmosphere contained 46% CO2. 1.3- Development of resistance in T.castaneum to a
combination of phosphine + carbon dioxide : Results showed that the lethal time values recorded to obtain certain kill were significantly higher for the 16th generation at the two test
temperatures than for the laboratory strain (Parent). At the 16th generation,
the adults of Ticastaneum showed 19.4 - fold resistance to a combination
of phosphine plus carbon dioxide at 26 ± 1°C and 18.5 - fold resistance at
6 ± ] °C when compared with the laboratory stock at the LT 50 - level.
This result indicated clearly that ’Lcastaneum adults have the
genetic potential to develop resistance to an atmosphere containing a
combination of 40 vpm PH3 + 46% carbon dioxide. 2.1. The biological characteri tic of the re i tant train of
T.castaneum to a combination of P 3 + C02 in compari on to the parental stock.
Results showed that, the resistant strain of T’castaneum (F 12)
selected to a mixture of 40 vpm phosphine + 46% carbon dioxide laid
ignificantly higher number of eggs than the laboratory strain. But no
significant differences were found between the laboratory and PH3 CO2
resistant strain (F 12) of 7: castaneum in the average pre-ovipostion period
and sex ratio. The total developmental period was significantly longer for
the laboratory strain than the PH3 + CO2 - resistant strain. The average
incubation period was significantly longer in the laboratory strains than the PH ... + CO2 resistant strain. The larval mortality was considerably higher
for the PH3 + CO2 resistant strain. The average hatching rate of the eggs
significantly increased for the PH3 + CO2 resistant strain. The mortality
rate of the larval instars was significantly higher for the PH3 + CO2 -
resistant strain than for the laboratory strain. It was also observed that the emergence rate of the adults was unaffected and amounted to 100% for the two strains.2.2. The population dynamics of Tribolium castaneum resistant strains (PH3 - RS, PH3 + C02 - RS) in comparison to the
parental stock (laboratory strain).
Results revealed that the mean adult mortalities were 2.23%, 4.44%
and 13.63% for the laboratory, PHrRS, and PH3 + C03 - RS,
respectively. These values were obviously higher in case of the PH3 +
CO2 - RS than the other strains. The population growth rates were 0.054,
0.053, and 0.053 for the labortory, ~H3 - RS and PH3 + CO2 - RS
respectively. It is evident that his value was slightly greater for the
laboratory strain than the other strains.The maximum number of the alive adults recorded in the food
during an observation period of six months was 1090 805, 664 for the
parental stock, phosphine resistant strain, and PH3 + CO2 - RS. resistant
strain, respectively. These values were reached after 120 days in all tested
strains.Although the resistant strains to phosphine and the strain resistant to
a combination of PH3 + CO2 laid significantly higher numbers of eggs in
comparison to the laboratory strain, the adult populations recorded during
the observation period of six months were in contrary lower for the two
resistant strains than the laboratory strain.Thi could be due to the lower hatchability of egg in the phosphine
resistant strain and higher mortalities during the various developmental
tages of the two resistant strains in comparison with the parental stock.