Studies were undertaken to establish the effects of low temperatures on the rate of respiration in larvae
and adults of a susceptible strain of the cigarette beetle Lasioderma serricorne. The results showed that there
was a consistent decrease in the rate of respiration in L. serricorne with a decrease in temperature from 251C
to 51C. The rate of respiration was slightly affected by circadian rhythm in adult beetles, but not in larvae.
The levels of phosphine taken up by different life stages of the beetle were also determined using [32P]-
radiolabelled gas. A comparison between susceptible and phosphine resistant strains showed that the
mechanism of resistance in L. serricorne involves a reduced uptake of the fumigant.
The uptake of [32P]-phosphine by different life stages of resistant L. serricorne declined with a decrease in
temperature from 251C to 51C. Similarly, the uptake by susceptible L. serricorne decreased from 251C to
101C, but there was a comparatively higher uptake at 51C and consequently a higher mortality at the end of
the exposure. The significance of the findings in relation to control strategies is discussed.
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