Population-Growth of the Pea Aphid, Acyrthosiphon pisum (Homoptera: Aphididae) after Exposure to Extreme Temperatures

Viviparous, parthenogenetic populations of 1st instars and prereproductive or teneral pea aphids, Acyrthosiphon pisum (Harris), were exposed to 39°C or −12°C for varying times. Intrinsic rates of increase for surviving populations (Gen 1) and their progeny (Gen 2) were calculated. Rate of population growth decreased with increased duration of exposure for all Gen 1 populations. This decrease, which was more pronounced in populations exposed in the teneral stage, was due to decreased fecundity and longevity and increased developmental time. These effects were carried over into Gen 2 populations, particularly after exposure in the teneral stage. It is concluded that temporary exposure of populations to extreme temperature may decrease rates of growth of surviving populations. This effect may extend over subsequent generations and the age-structure of the population at the time of exposure may affect its subsequent growth rate.