BioControl 44: 281–289, 1999. © 1999 Kluwer Academic Publishers. Printed in the Netherlands. The influence of temperature, photoperiod and plant type on the predation rate of Macrolophus pygmaeus on Myzus persicae D.CH. PERDIKIS, D.P. LYKOURESSIS and L.P. ECONOMOU Laboratory of Agricultural Zoology and Entomology, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece Received 11 May 1998; accepted in revised form 21 July 1999 Abstract. The effect of temperature and photoperiod on the rate of predation of nymphs and adults of the predator Macrolophus pygmaeus was studied using Myzus persicae prey feeding on egg-plant and pepper plants. The experiments were conducted at three photoperi- ods (16L:8D, 12L:12D and 8L:16D), three temperatures (20, 25 and 30 ◦ C), and at 65% r.h. The rate of predation increased with temperature. Predation rate was affected by photoperiod on pepper but not on egg-plant. Females and fifth instar nymphs were the most voracious stages followed by third and fourth instar nymphs and males. First and second instar nymphs consumed far fewer aphids. Predation rate was higher on leaves of pepper than egg-plant, especially at 30 ◦ C. Variation in the efficacy of this predator is discussed. Key words: Macrolophus pygmaeus, photoperiod, predation rate, temperature, predator Introduction The importance of the predator Macrolophus Fieber (Heteroptera: Miridae) in reducing populations of whiteflies and aphids on tomato and other crops has been described by several authors (Malausa et al., 1987; Arzone et al., 1990; Alomar et al., 1994; Goula and Alomar, 1994; Perdikis and Lykouressis, 1996; Sampson and King, 1996). Macrolophus caliginosus Wagner can complete its development by feeding on Trialeurodes vaporariorum West- wood, Myzus persicae (Sulzer), Macrosiphum euphorbiae (Thomas), and Aphis gossypii Glover (Fauvel et al., 1987; Alvarado et al., 1997). Like M. caliginosus, Macrolophus costalis Fieber can develop on populations of T. vaporariorum and M. persicae (Brezinski, 1988). The main biological control agent of aphids found in tomato fields in central Greece during 1992 and 1993 was Macrolophus pygmaeus Rambur. Laboratory studies indicated that M. pygmaeus can develop successfully under a relatively wide range of temperatures on whiteflies, aphids and mites feeding on tomato, egg-plant and pepper plants (Perdikis and Lykouressis,