Seasonal abundance of the corn leaf aphid, Ropalosiphum maidis (Fitch) and Coccinillid beetles on sorghum cultivars
ANBAR JOURNAL OF AGRICULTURAL SCIENCES,
2010, Volume 8, Issue 4, Pages 482-491
AbstractField studies were conducted at the college of Agriculture/ Abu-Ghraib, Baghdad during the spring season/ 2008 to evaluate the Sesonal abundance and susceptibility of three sorghum cultivars (Inkhad, Rabih, Kafir) and hybrid money maker against the infestation by the leaf corn aphid, Ropalosiphum maidis (Fitch) and its relationships with the predator Coccinillid beetles. Results indicated the susceptibility of all sorghum cultivars & the hybrid money maker to infestation by aphid to a varying degrees , Infestation by the leaf corn aphid, R. maidis had started after germination during April and population density has increased gradually and reached its peak of 301,117.75 ,107.75 and 33.5 individual /10 plants for cultivars Rabih, Inkhad, Kafir and money maker respectively, While the general means of Sesonal abundance aphids were, 108.60, 64.20, 47.38 and 30.08 individual/10 plants for the cultivars above respectively during the spring season. Coccinillids beetles began to arrive to sorghum fields early in few numbers (3-4) beetle/plot during April, then began to increase gradually to reache its peaks of, (49.50, 43.50,40.50and 37.75) beetle/plot on cultivars Inkhad,Rabih, kafir and money maker respectively during May. This increase coincide with aphid peaks and the arrival of sorghum plants to flowering. Results indicated an association under a high significant level of 0.01 between numbers of R. maidis and the Coccinillids, (a value of r= 0.964). Mainly, two species of coccinillids were observed feeding on aphid, R.maidis, The seven- spot ladybird, Coccinella septumpunctata L. and 11-spot ladybird, Coccinella undecimpunctata L. The role of the hybrid money maker , and the importace of leaving a low level of corn leaf aphid as food for the Coccinillid predators in sorghum field also discussed .
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