Effect of plant age and species on population growth of two Rhopalosiphum maidis (Fitch) lineages

The corn leaf aphid Rhopalosiphum maidis (Fitch) can feed on various cereal crops and transmit viruses that may cause serious economic losses. To test the impact of host plant species and age on R. maidis, we identified the survival and reproduction rates of two R. maidis populations (Beijing and Mangshi) via a direct observation method in laboratory on 10 cm high maize seedlings (small maize), 50 cm high maize seedlings (high maize) and 10 cm high barley seedlings (barley). The Beijing (BJ) population performed significantly better than the Mangshi (MS) one on 50 cm high maize seedlings and barley seedlings, while both populations could not survive on maize seedlings in 10 cm height. As smaller maize seedlings were fatal to the corn leaf aphid, we hypothesized that it may be due to the secondary metabolites synthesized by maize seedlings and our results also give the implication for aphid control on maize which will be discussed.