Susceptibility of Four Maize Hybrids to Infestation with Corn Leaf Aphid, Rhopalosiphum maidis and Population Dynamics of Ladybug (Coccinellidae) Aphid Predator in Iraq

Abstract

A field study was conducted in Nineveh Governorate during the spring and fall seasons of 2023 to determine the population density of corn leaf aphids, Rhopalosiphum maidis (Fitch), and test the susceptibility of corn hybrids to R. maidis and its relationship to the numbers of ladybug (Coccinellids) aphid predator. The results obtained showed that there was a variation in the sensitivity of the corn hybrids to infestation with R. maidis. The infestation on all four hybrids began in April and the population density started to increase and reached its peak during the spring season in mid-May, reaching 180.40 120.50, 54.19, 35.29 individuals/10 plants for the hybrid varieties Konsens, Zoan, Jameson and Samurai, respectively. Whereas in the fall season (September), the aphid population reached 190.81, 140.50, 70.60 and 45.50 individuals/10 plants of the same four hybrids, respectively. As for the ladybug predator, it was recorded in small numbers at the beginning of the spring season, and reached in May 15.4, 20.4, 27.6 and 13.1 ladybugs per plot for the same hybrids, respectively, whereas, their numbers in the fall season (September) reached 20.7, 22.1, 25.3 and 35.0 ladybugs/plot for the same corn hybrids, respectively.

Keywords:

Corn hybrids, insects, ladybug, corn aphid, Rhopalosiphum maidis.