The Effect of Photoperiod and Temperature on Reproduction in <i>Acyrthosiphon pisum</i> (Harris) and on the Forms produced

Abstract

The effect of photoperiod and temperature on the production of the various forms of Acyrthosiphon pisum (Harris) has been studied. In this study apterous virginoparous females were exposed throughout their lifetime to two photoperiods (8 hr./24 hr. and 16 hr./24 hr.) and six different temperatures. At each of the temperatures the apterae (parent Aphids) received one of four treatments of photoperiod, i.e., (1) 8 hr./24 hr. photoperiod throughout their whole life; (2) 8 hr. /24 hr. photoperiod during the period from birth until the last (imaginal) moult (nymphal period), followed by 16 hr./24 hr. photoperiod from the last (imaginal) moult until death (the adult period); (3) 16 hr./24 hr. throughout life; (4) 16 hr./24 hr. during the nymphal period followed by 8 hr./24 hr. during the adult period. The offspring produced by the various parents were collected at successive intervals, and their form determined. Four main forms of offspring were produced: apterous and alate virginoparae, males and oviparae. In addition, a subsidiary form of the apterous virginoparae was obtained, which had sensoria on the hind tibiae.