Diapause Induction in the Stem Corn Borer, Sesamia nonagrioides (Lepidoptera: Noctuidae)
Eizaguirre, Matilde; Albajes, Ramon
Sesamia nonagrioides (Lefèbvre 1827) is one of the main insect pests of maize in Mediterranean regions located below the 45th parallel. The number of generations in the year largely depends on the timing of the onset of diapause. The present work obtaines in laboratory experiments thermal (T) and photoperiodic (Php) critical levels which induce diapause in local populations (Lleida 41° N). T affects the Php response curve. A 50 % diapausing response was recorded at daylengths of 14 h 22 min, 13 h 55 min and 13 h 45 min when larvae were reared at 18°, 21.5° and 25°C respectively. These critical Php levels were validated when diapause intensity was measured in the developed larvae collected in the field from VII to II. Indications on the effect of maize phenology on diapause induction in S. nonagrioides were obtained.