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Intergenerational acclimation in aphid overwintering
- POWELL, S.J., BALE, J.S.
- Ecological entomology 2008 v.33 no.1 pp. 95-100
- Hemiptera, Sitobion avenae, acclimation, adults, cold, cold tolerance, instars, nymphs, overwintering, progeny, rearing, reproduction, siblings
- 1. When first instar nymphs and adults of the grain aphid Sitobion avenae (Fabricius) (Hemiptera: Aphidiae) were maintained in long-term cultures (>6 months) at 20 °C and 10 °C, the LT₅₀ decreased from -8 and -8.8 °C to -16.0 and -13.5 °C, respectively. 2. When aphids from the 20 °C culture were transferred to 10 °C, there was a progressive increase in cold tolerance through three successive generations. Transfer of newly moulted pre-reproductive adults reared at 10 °C for three generations back to 20 °C resulted in a rapid loss of cold hardiness in their nymphal offspring. 3. In all generations reared at 10 °C, first born nymphs were more cold hardy than those born later in the birth sequence. The LT₅₀ of nymphs produced on the first day of reproduction in the first, second and third generations maintained at 10 °C were -14.8, -17.0 and -16.6 °C, respectively. Thereafter, nymphal cold hardiness decreased over the subsequent 14 days of reproduction in each generation at 10 °C with mean LT₅₀ values of -10.3, -12.6 and -14.8 °C, respectively. By contrast, the cold tolerance of first born nymphs of aphids reared continuously at 20 °C did not differ in comparison with later born siblings. The LT₅₀ of adult aphids was also unaffected by ageing. 4. The ecological relevance of these findings is discussed in relation to the overwintering survival of aphids such as S. avenae.