Oviposition preference of the amaranth stem borer, Aerenea quadriplagiata (Coleoptera, Cerambycidae) under field conditions

Amaranth is currently considered a "strategic grain crop" because of its broad genetic variability, hardiness, and nutritional value. In the Argentinean Pampas Region, one of its major pests is the cerambycid stemborer, Aerenea quadriplagiata. This study aimed to evaluate the oviposition preference of this pest related to both different cultivars and morphometric characteristics of the amaranth plant. In the experimental field of the Universidad Nacional de Lujan, plots with different cultivars of Amaranthus were planted in two consecutive years. The presence and number of oviposition and oviposition effective ratio (with development of larvae) were related to the cultivar, the height and the stem diameter. The horticultural cultivar presented the lowest oviposition effective ratio, the lowest percentage of plants with oviposition and larger stem diameter with a 50% chance of being oviposited by A. quadriplagiata. These results suggest that the behavior of female stem borer is influenced by both the cultivar and stem diameter and that A. mantegazzianus L. cv horticola is the most recommended cultivar in areas where there is high incidence of the stem borer.