Biomedical Engineering Reference
In-Depth Information
(L.) in various atmospheres of CO
2
, N
2
, or He, and in various combinations of CO
2
-
air and CO
2
-O
2
. Adults of both species when exposed to either of the three gases
had an increase in mortality with an increase in temperature from 16 to 27°C. It
was noted that 100% CO
2
was less toxic to both species than any combination of
CO
2
(40 to 90%) with either air or O
2
. Adults of
S
.
granarius
were the most
susceptible to atmospheres of CO
2
, N
2
, or He, followed by larvae, pupae, and eggs.
Likewise, adults of
S
.
oryzae
had the highest susceptibility followed by larvae, eggs,
and pupae under similar gas conditions. Jay and Pearman
63
tested the susceptibility
of the adults of
T
.
castaneum
,
T
.
confusum
(duVal), and a malathion-resistant strain
of
T
.
castaneum
under several gas compositions. In most cases an increase in CO
2
or N
2
combined with a decrease in O
2
resulted in an increase in insect mortality.
Three days of exposure to <1% O
2
coupled with >95% CO
2
or >99% N
2
resulted
in 100% mortality of all insects. Both inter- and intra-specific differences in mortality
were observed under altered gas conditions when other variables like temperature,
relative humidity, and insect age were kept relatively constant. In a similar study,
Aliniazee
64
investigated the effect of several binary gas mixtures containing CO
2
,
N
2
, or He with O
2
(2 to 20%) on the mortality of
T
.
castaneum
and
T
.
confusum
.
The adults of both species were killed when exposed to <2% O
2
in combination
with N
2
or He for about 96 h. Carbon dioxide (80 to 98%) alone appeared to be
responsible for mortality of insects when used in combination with O
2
concentration
ranging from 20 to 2% as all combinations produced similar results. The data
obtained by exposing mature and immature stages of both species to 100% CO
2
indicated that adults were the most susceptible stage followed by larvae, eggs, and
pupae. The insect mortalities increased with an increase in temperature (15.6 to
26.7°C), and a decrease in relative humidity. Under airtight conditions, the adults of
T
.
castaneum
were able to use the available O
2
more efficiently (O
2
concentration
reduced from 20.9 to 1.7% in 7 d) than those of
T
.
confusum
(O
2
concentration reduced
from 20.9 to 1.6% in 5 d) indicating differential respiration rates of these species.
The adults of five stored-grain insects (
S
.
granarius
,
T
.
castaneum
,
Oryzaephilus
surinamensis
(Linnaeus),
Cryptolestes ferrugineus
(Stephens), and
Rhyzopertha
dominica
(F.)) were exposed to atmospheres similar to those obtained by the com-
bustion of hydrocarbon fuels (10 to 30% CO
2
, 0.5 to 2.6% O
2
, and balance N
2
) at
20°C and 70% relative humidity.
65
The gas mixtures containing 1.0 to 1.6% O
2
and
>10% CO
2
were lethal to all species after 7 days of exposure.
C
.
ferrugineus
was
relatively more tolerant than any other species when O
2
concentration was 2.0 to
2.6%.
S
.
granarius
survived the longest at an O
2
concentration of 0.5%. Jay
59
treated
immature stages (1 to 5 week old) of
S
.
oryzae
and
R
.
dominica
with an atmosphere
containing high concentration of CO
2
(>50%) and low O
2
(<12%) at high relative
humidity (>50%), and at two different temperatures (2 and 16°C). After an exposure
for 2 weeks to 60% CO
2
, 100% reduction in emergence was obtained at both
temperatures.
S
.
oryzae
was relatively more susceptible than
R
.
dominica
at low
temperature. He also studied the mortality of
Trogoderma glabrum
(Herbst) and
T
.
variabile
(Baillon) larvae when exposed to 61 and 99% CO
2
at elevated tem-
peratures (33 and 38°C). Complete mortality was obtained only with 99% CO
2
at
38°C. The mortality ranged from 15 to 32% at 61% CO
2
at both temperatures.
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