R. Atılhan and M.S. ¨ Ozg¨ okc ¸e (2002) Phytoparasitica 30(5):443-450 Development, Fecundity and Prey Consumption of Exochomus nigromaculatus Feeding on Hyalopterus pruni R. Atılhan and M.S. ¨ Ozg¨ okc ¸e Development, survival and reproduction of Exochomus nigromaculatus (Goeze) were studied in the laboratory at four constant temperatures from 20 C to 35 1 C in 5 C increments, 60 5% r.h. and 16 h of artificial light (5000 lux). Development time from egg to adult ranged from 22.4 days at 20 C to 10.6 days at 35 C, and required 278 degree-days above a threshold estimated to be 9.11 C. Survival was the highest at 25 C and the lowest at 35 C. Longevity of females declined significantly with increasing temperatures, ranging from 120.7 days at 20 C to 46.6 days at 35 C. Mean generation time became shorter with increasing temperatures. The intrinsic rate of increase of individuals kept at 30 C was significantly greater than that of individuals kept at the other temperatures tested. Fourth larval instars and adults of E. nigromaculatus displayed a Type II functional response to H. pruni densities. Searching rate of fourth instar larvae and adults was similar, but handling time was shorter for female adults. Results obtained in this study showed that the optimal temperature for population growth of E. nigromaculatus was 30 C and this coccinellid predator may have potential as a biological control agent for H. pruni because of its feeding capacity. KEY WORDS: Exochomus nigromaculatus; development; fecundity; prey consumption; Hyalopterus pruni; mealy plum aphid. INTRODUCTION Hyalopterus pruni (Geoffroy) (Homoptera: Aphididae), the mealy plum aphid, is a major pest of stone fruit trees, especially apricot and plum, in the Van region of eastern Turkey (2,20). A cosmopolitan species with worldwide distribution (3,4,5,9,17), it sucks plant sap, inducing plant deformation and producing copious amounts of honeydew. It has been reported also as a virus vector, specifically of plum pox virus (4,13). Chemical control measures applied against this pest may disrupt other biological control. Therefore, biological control or integrated management should be considered options for controlling this pest. There have been some studies indicating that natural enemies may be effective against H. pruni. For instance, integrated management experiments carried out with Praon volucre Haliday (Hymenoptera: Aphidiidae) against H. pruni in Czechoslovakia (17) and against Aphidius transcaspicus (Hymenoptera: Aphidiidae) in Georgia (USSR) (18) gave good results. Coccinellids are well known all over the world as important natural enemies of aphids (7,8). In surveys carried out in the Van region, many natural enemies of H. pruni were found, among them the coccinellid predator Exochomus nigromaculatus (Goeze) Received Jan. 6, 2002; received in final form July 23, 2002; http://www.phytoparasitica.org posting Aug. XX, 2002. Y¨ uz¨ unc¨ u Yl ¨ Universitesi, Ziraat Fak¨ ultesi Bitki Koruma B¨ ol¨ um¨ u, 65080 Van, Turkey. *Corresponding author [Fax: +90-432-2251104; e-mail: remziatlihan@hotmail.com]. Phytoparasitica 30:5, 2002 443