Effect of sowing dates on the populations of three major insect pests and associated natural enemies throughout the growth stages of maize plants

Abstract

In Egypt, maize is an important crop that is attacked by various pests. In the present study, the effect of maize planting dates on the populations of insect pests and their natural enemies were investigated throughout the growth stages of maize plants. The maize planting dates were at the beginning of May, Jun, and July in the 2019 season and were repeated in the 2020 season. Samples were collected weekly to determine the populations of the insect pests, Limothrips cerealium (Haliday, 1836), Rhopalosiphum maidis (Fitch, 1856), and Sesamia cretica Lederer, 1857 and their natural predators. For the first sowing date, the infestation percentage of L. cerealium and S. cretica were most substantial, especially in the seedling and precorn formation stages. For the third sowing date, the number of R. maidis was most substantial, especially in the corn formation stage. Three predators were associated with these insect species; of these predators, Coccinella undecimpunctata (Linnaeus, 1758), Scymnus interruptus (Goeze, 1777), and Chrysoperla carnea (Stephens, 1836) were observed at the highest numbers during all sowing dates. A highly significant correlation existed between populations of S. interruptus and the three insects across the two seasons. Data suggest that the percentage of thrips, aphids, and stem borers infestations can be minimized by planting maize varieties in June.