Bulletin of Entomological Research (2003) 93, 39–45 DOI: 10.1079/BER2002207 Biological characteristics of the mirids Macrolophus costalis and Macrolophus pygmaeus preying on the tobacco form of Myzus persicae (Hemiptera: Aphididae) J.T. Margaritopoulos 1 , J.A. Tsitsipis 1 * and D.C. Perdikis 2 1 Laboratory of Entomology and Agricultural Zoology, Faculty of Crop and Animal Production, University of Thessaly, Fytokou st., 38 446, Nea Ionia, Magnesia, Greece: 2 Laboratory of Agricultural Zoology and Entomology, Agricultural University of Athens, Athens, Greece Abstract Biological and population parameters of the predatory bugs Macrolophus costalis Fieber and Macrolophus pygmaeus Rambur preying on the tobacco aphid Myzus persicae (Sulzer) were examined. Tobacco was used as host plant and all experiments were carried out at 23°C and L16:D8. In M. costalis, the developmental time for eggs and the total duration of nymphal instars was 13.1 and 22.2 days and in M. pygmaeus 13.0 and 20.2 days, respectively. Both species completed their nymphal development feeding only on plant juices although they required significantly more time to attain adulthood than when feeding on prey. The longevity of M. costalis females and the preoviposition period were 49.9 and 5.6 days and those of M. pygmaeus were 50.3 and 6.3 days, respectively. Adult males showed a higher longevity than females in both species. The intrinsic rate of increase and the mean total number of eggs laid were 0.0644 and 121 in M. costalis and 0.0615 and 104 in M. pygmaeus, respectively. Mean total aphid consumption by nymphs of M. costalis was 61 aphids, about twice that of M. pygmaeus (37 aphids). Total aphid consumption by a male and female pair of M. costalis and M. pygmaeus until the death of the female was 244 and 285 aphids, respectively. The results of the study are discussed in relation to the impact of the two predatory bugs on tobacco aphid populations. Introduction The tobacco feeding form of Myzus persicae (Sulzer) (Hemiptera: Aphididae) is considered to be the most important pest of tobacco, Nicotiana tabacum L. (Solanaceae), in Greece, since it causes serious damage to all types of tobacco throughout all tobacco-growing regions. The aphids damage the plants either by sucking plant juices or by the honeydew they produce, resulting in lower yields and poor product quality (Feinstein & Hanna, 1951; Throne & Lampert, 1985). In addition, they cause serious indirect damage by transmitting important non-persistent viruses (Katis et al., 1992). Approximately 230 tonnes a.i. of insecticides were used for the control of the tobacco aphid in Greece in 1995 (Tobacco Institute of Greece, personal communication). A better understanding of the impact of natural enemies on the populations of the tobacco aphid might assist in reducing the use of insecticides and in improving the quality of tobacco. In Greece, various species of predators of the tobacco aphid have been reported. Among them Macrolophus costalis Fieber (Hemiptera: Miridae) and Macrolophus pygmaeus Rambur (Hemiptera: Miridae) were found on tobacco in large numbers in regions of Central and North Greece (J.A. Tsitsipis, unpublished data; Lykouressis et al., 2000). Macrolophus costalis has also been reported as an important biological control agent of Thrips tabaci Lindeman *Author for correspondence *Fax: +30 0421 93286 E-mail: tsitsipi@uth.gr