Effects of short-term heat stress on the performance of the predatory gall midge Aphidoletes aphidimyza (Diptera: Cecidomyiidae)

Aphidoletes aphidimyza is one of the most important natural enemies of aphids, but its efficiency in aphid control is affected by temperatures. We measured the life history parameters of A. aphidimyza by exposing its different life stages to 35 degrees C for 3, 6, and 12 h. The results showed that the survival rate of eggs, first instar larvae, pupae, and mated males was decreased significantly with the increase of the exposure duration, whereas the survival rate of third instar larvae and adult females was not significant different before and after the exposure. The short-term high temperature stress also significantly decreased the predation of first and second instar larvae, whereas the predation of third instar larvae was not affected. In addition, the heat stress did not affect adult egg production, longevity, and offspring hatching rates, regardless of mating status. These results demonstrated that short periods of heat stress negatively influenced A. aphidimyza development, but the effect was dependent on duration and developmental stage. Therefore, in order to achieve the best predatory efficacy of gall midges against aphid pests, the heat stresses above 35 degrees C should be avoided.