Effects of temperature, feeding position and crop growth on the population dynamics of the rose grain aphid, Metopolophium dirhodum (Hemiptera: Aphididae)

The population dynamics of Metopolophium dirhodum were studied on winter wheat seedlings at constant (10-degrees-C, 15-degrees-C, 20-degrees-C, 25-degrees-C and 30-degrees-C) and fluctuating (12(night)-22(day)-degrees-C) temperatures, and during booting to early inflorescence, and anthesis to early milky ripe stage, at 19-degrees-C. The pre-reproductive development time was decreased by increasing the temperature from 10-degrees-C to 25-degrees-C. It was significantly shorter when the aphids were feeding during booting to early inflorescence than during anthesis to early milky ripe stage but was similar when the aphids were feeding on the flag, second or third leaves. The total number of nymphs produced/apterous adult was not significantly affected by temperature from 10-degrees-C to 25-degrees-C but adult reproductive lifespan was reduced by increasing temperature from 10-degrees-C and 12-22-degrees-C to 15-degrees-C, 20-degrees-C and 25-degrees-C. The daily intrinsic rate of increase changed from 0.11 to 0.25, and the cohort generation time decreased from 31 to 12 days, with increase of temperature from 10-degrees-C to 25-degrees-C. Reproductive rate was similar when the aphids were feeding on the flag, second or third leaves during booting to early inflorescence at 19-degrees-C. The reproductive rate was higher when the aphids fed from mid-inflorescence to mid-milky ripe stage than from mid-milky to early ripe stage. These results were compared with those from other studies. Predictions from a simulation model using development and reproductive rates from this study and literature were compared and the former rates resulted in a more accurate prediction of field observations in 1979, an outbreak year.