Thermal requirement and temperature thresholds for development of peach-potato aphid, Myzus persicae (Sulzer) on potato in the subtropical plains of India

In India, potatoes are cultivated mainly in the sub-tropical Indo-Gangetic plains during winter. The winged morphs of peach-potato aphid, Myzus persicae (Sulzer) appear on the potato crops in the first fortnight of November and continue to reproduce parthenogenetically till March and disappear afterward. To determine its thermal requirement, we evaluated the immature development and survival of M. persicae on potato at eleven constant temperatures, for both the apterous and alate morphs. Myzus persicae nymphs developed to the adult stage at constant temperatures from 5.4 to 31 degrees C but failed to achieve adult emergence at 32 degrees C, the highest temperature. However, winged adults were produced only at set temperatures from 5.4 to 26.4 degrees C. The immature survival rate was high at 7.3 through 26.4 degrees C and decreased considerably beyond this range. The lower temperature thresholds (T-min) were estimated as 4.13 +/- 0.38 degrees C and 4.35 +/- 0.74 degrees C for apterae and alatae, respectively. The thermal requirement (degree days) for the development of alate morphs was found appreciably higher in comparison to apterae, 128.20 +/- 7.06 and 108.69 +/- 3.07, respectively. Among the non-linear models, the estimates obtained from Bayoh model reflected the actual experimental value of temperature thresholds. Based on the accumulated degree day's calculation, the alate morphs could complete 8.9 - 10.9 generations while the apterous morphs could complete 10.7 - 13.1 generations in the whole growing season. This information will help understand the population growth of the aphid in the sub-tropical plains and improve the efficacy of management practices.