The response of two strains of Hylemya antiqua (Diptera: Anthomyiidae) to a constant and an alternating temperature regime

The effect of an alternating and a constant temperature regime on some aspects of the biology of two strains of Hylemya antiqua were studied. One strain was a laboratory strain, the other a newly colonized wild strain. Several population statistics were assessed and life tables constructed. Significant differences between the strains were recorded. The laboratory strain mated significantly better under both environments than the wild strain, it also oviposited earlier and lived longer. No difference between the strains was recorded for either total egg production or oviposition rate. The wild strain larvae survived significantly better than the laboratory strain larvae and produced larger pupae. As the weighted mean temperature of the alternating regime was 16.6"C compared with the constant regime of 23°C many temperature dependent processes were retarded. Nevertheless as the alternating temperature increased larval survival and increased pupal size, this temperature regime has now been adopted for the routine laboratory rearing of H. antiqua larvae. The net reproductive rate, R,, and the intrinsic rate of increase, r, were calculated for both strains in both environments. The wild flies had the highest R, at the alternating temperature and the lowest at the constant temperature. This trend was completely reversed when r was calculated as this statistic takes into account generation time, which was much shorter in the constant temperature. The results were discussed in the framework of the quality of the laboratory stock in relation to its use in a genetic control programme.