Relación entre las preferencias de oviposición de las hembras y los sitios de alimentación de las larvas del barrenador del brote de la soja, Epinotia aporema (Lepidoptera, Tortricidae)

Abstract

The oviposition behavior of phytophagous insects is crucial in deterrnining the probability of the progeny reaching a suitable feeding site. Thus, those habitats, individual plants, or plant parts, more adequate for growth and survival should be selected. Although llie preferred feeding sites of Epinotia aporema larvae are soybean buds (the most pubescent part), a greater proportion of its eggs are laid mainly on nodes (the less pubescent part), and secondarily on expanded leaves. This apparent contradiction led us to ask some questions about the moving capacity of the newly emerged larvae to the buds and the benefit of this oviposition behavior ¡n temas of survival, growth and fecundity. Egg hatching was sinuilaled by placing newly emerged larvae on nodes and expanded leaves of soybean plants and the fate of larvae under controlled conditions was recorded after 4 days. Proportions of larvae found ¡n each plant part within each treatment were analysed using a Chi-square test. Larval survival and pupal weight were estimated for groups of larvae fed on buds and leaves and data were analysed by ANOVA. Significant differences ¡n the proportion of larvae found in different plant parts between the two treatments (nodes and expanded leaves) were registered. A greater proportion of larvae . emerging on nodes reached the buds compared to those emerging on leaves. More than 60% of larvae emerged on leaves remained feeding on this site. Survival and pupal weight were significantly greater for the larvae fed with buds than for the larvae fed wills leaves. Pubescence would determine, at least in part, the oviposition behavior of ilie female. Our results indicate that this behavior maximizes some “fitness” components like larval survival and larval growth.