Coordinating Supplies of Southwestern Corn Borers (Lepidoptera: Pyralidae) and Fall Armyworms (Lepidoptera: Noctuidae) by Manipulating Development Time Using Temperature1

Abstract

To better coordinate the supply of larvae with plant growth for resistance studies, laboratory and field studies were conducted to determine if development of southwestern corn borers, Diatraea grandiosella Dyar, and fall armyworms, Spodoptera frugiperda (J. E. Smith), could be better controlled in the laboratory by alternating the numbers of days that the insects were held at either 21.1 or 26.7°C (day–temperature combinations). When reared on artificial diet and held continuously at 26.7 and 21.1°C southwestern corn borers developed from 1-d-old larvae to adults in 31 to 57 d. Fall army worms completed development between 24 and 41 d. No significant differences were detected among day–temperature combinations for overall survival and normality of adults in either species. Days to hatch for southwestern corn borer and fall armyworm ranged from 5 to 9 and 3 to 5 d, respectively, when eggs were held at different combinations of time and temperature. Percent egg hatch and establishment of larvae on an artificial diet did not differ significantly among egg day–temperature treatments for either insect. Larvae from eggs that were held at different day–temperature combinations caused the same amount of leaf-feeding damage when comparisons were made within a resistant or a susceptible corn hybrid.