Carbon dioxide and chilling are sometimes used to immobilise insects for laboratory research. Both of these methods are known to have short-term effects on behaviour and physiology in Drosophila, but their long-term impacts are unknown. We exposed female D. melanogaster adults to high CO(2) concentrations (4h at 18,000ppm) and chronic cold (72h at 4°C). The carbon dioxide exposure increased chill coma recovery time, but did not result in changes in offspring number, sex ratio, or size. By contrast, the cold exposure resulted in fewer, smaller offspring, and resulted in a male-biased sex ratio compared to controls. There was no significant interaction between CO(2) and cold. We conclude that although caution must be used in choosing an immobilisation method, CO(2) appears to have less long-term impact than cold.
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