الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
This work was carried out at the Institute of
stored products protection of the Federal Biological
Research Centre for Agri. and Pbrestry in Berlin
Dahlem (Fed. Rep. of l}ermany). The main objective- of
these investieations was to study the effect of the
inert gas carbon dioxide on the effecaoy of phosphine
against some stored product insects. Larvae and pupae
of Sitotroga cerealella and adults of Sitophilus oryzae
and Tribolium castaneum were used in the Experiments.
A recirculatory multi-flask apparatus was designed
to prOVide a fumigation chamber for test insects. Phosphine
was generated from PHOSTIXI~-Pelletts.
Biological studies were carried out to determine
the appearance times of larval and pupal stages of
Sitotroga cerealella and adult emergence of Sitophilus
oryzae and Tribolium .castaneum • It esults obtained were
recorded.
Data achieved could be summarized under the following
topioar
I. Effect of phosphine on the tested insects:
I.l. Larvae and pupae of Sitotroga cerealella:
Probit analyses for toxicological data, obtained
to find the relative toxicity of phosphine to larval
and pupal stages of Sitotrolljacerealella exposed to
varying phosphine concentrations for 2, 4, 8, 24, 48
and 72 hr. at 20°C and 28°C, showed that the LC50 of
phosphine decreased from average, 1609~g/L at 2 hr.
to 4.59~g/L at 72 hr. for larvae at 200C and from
1397 ~g/L to 4.36 ~5/Lat ~80C.
In case of pupae the LC50 of phosphine declined
from 3056 ~g/L to 8.17 ~g/L at 20°C and from 2297 ~g/L
to 8.00 ~g/L at 280C.
from these results we find that there was inver-
sible relationship between the concentration and exposure
period. Pupae of Sitotroga cerealella were more
tolerant to phosphine than larvae. PHOSTOXI~ at 280C
was more effective than at 200C.
I.2. Adults of Tribolium castaneum and S1tophllus oryzae:
The toxicological data obtained to find the relative
toxicity of phosphine to adults of Tribolium
castaneum ~nd Sitophilus oryzae exposed to different
concentrattons and for 2, 4, 8, 24. 48 and 72 hr.
exposure prriods at 28°C showed that the LC50 of
phosphine decr-eased from 70.4 /lg/L at 2 hr. to 2.)
~/L at 72 hr. for Tribolium castaneum and from 128
~/L at 2 hr. to 1.8/lg/L at 72 hr. for SitophiluS
oryzae.
There was also inversible relationship between
the concentration and the exposure period.
II. Effect of carbon dioxide alone on the tested insects:
The results indil~ated that carboh dioxide at short
exposure periods of 2, 4 and 6 hr. had a negligible
effect on the mortality of larval and pupal stages of
.§. cerealella.
At longer exposure periods of 24. 48 and 72 hr.
the effect of CO2 on the mortality of larvae and pupae
of .§. cerealella was noticeable. especially at 50 and
78% concentrations.
With respect to adults of Tribolium castaneum and
Sitophilus oryzae the effect of CO2 on the mortality
was very low at 2. 4 and 8 hr. at all carbon dioxide
concentrations but was high at 24, 48 and 72 hr. at 50
and 78% concentrations of CO2•
III. Ettect of mixtures ot phosphine and CO2:
Results obtained trom using mixtures ot LC50 of
phosphine and carbon dioxide concentrations showed high
increase in the mortalities ot larvae ot -S. cereal ella
at all exposure periods than of phosphine or carbon
dioxide alone.
In case of pupae the resu.1ts revealed an increase
in the mortalities at all exposure periods but this
increase was lower than for larval stage. The morta1ities
at 28°C were higher than at 200C.
Complete mortalities were recorded at all exposure
periods by using the mixtures ot carbon dioxide concentrations
and LC50 ot phosphine against adults ot T.
castaneum and §. oryzae at 280C.
Accordingly, llIixturesot vaI’3fingconcentrations
ot CO2 + LC50 ot PHJ induced higher insect-mortalities.
Therefore we could re~l1ce the phosphine dose requiered
in the tumigation , besides the potentiation ot the
action ot the gas.