Performance of corn [Zea mays] leaf aphid, Rhopalosiphum maidis (Fitch) (Homoptera: Aphididae) on selected maize [Zea] hybrids under laboratory conditions

The corn leaf aphid, Rhopalosiphum maidis (Fitch) is one of the most important pests of maize with worldwide distribution. The use of relatively resistant corn hybrids may lessen the harmful effects by this aphid; we therefore compared population growth parameters of R. maidis reared on six commonly grown maize hybrids in Iran, namely K3640/3×MO17, Simon, SC704, EXP1, VRE26×K18 and VRE27×K18. The experiments were carried out under conditions of 25±1oC, 60±10% RH, and a photoperiod of 16L8D. The development time and survival of aphid nymphs differed significantly among the maize hybrids tested. We also observed significant differences in aphid fecundity, resulting in large variations in population growth parameters, such as the intrinsic rate of natural increase (rm), net reproductive rate (R0), finite rate of increase (λ) and doubling time (DT). The rm values were highest for aphids reared on maize hybrids EXP1 and VRE27×K18, lowest for aphids reared on hybrid K3640/3×MO17, and intermediate for aphids reared on hybrids VRE26×K18, SC704 and Simon. Consequently, these results may offer useful information for planning a comprehensive program for IPM of the corn leaf aphid in Iran.