THE APPLE APHID, APHIS POMI (HOMOPTERA: APHIDIDAE), POPULATION ON APPLE UNDER AUTUMNAL CONDITIONS IN A CONTROLLED ENVIRONMENT CABINET

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Abstract
The apple aphid population density on 1-year-old trees under controlled conditions of decreasing temperatures and photoperiods equivalent to 1 August through 14 November 1967, remained almost static up to the time of apple tree defoliation. Alate forms disappeared and reproduction levelled off after a 13.3 hr, 17 °C light, and a 12 °C dark temperature were programmed. Aphids left the apex of the tree after vegetative growth ceased and became distributed more or less evenly over the older leaves. Egg deposition occurred after the photoperiod became shorter than 11.8/24 hr and temperatures less than 12 °C during the light period, 8 °C during darkness. This "autumn population" of aphids with no external detrimental biotic or extreme climatic effects produced winter eggs equal to one-third its numbers at the time of beginning oviposition.