Genetic variation in zoophagy and dietary shift in the phytozoophagous tarnished plant bug, Lygus lineolaris

Abstract

Phytozoophagous insects, whose diets mainly consist of plant resources, can also feed on animal resources. Within populations, individuals' diets may vary according to their food preferences. The environment and their genetics determine these preferences. The degree of prey voracity (zoophagy) is likely to influence the ecological interactions of individuals. In the case of crop pests, these ecological interactions determine their economic impact. This study aimed to measure the genetic variation in the degree of zoophagy of a phytozoophagous pest, the tarnished plant bug Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae). Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs were offered, as animal resources, to L. lineolaris individuals from 15 isofemale lines in a laboratory experiment, where individuals from each line did or did not have access to an alternative plant resource. The results indicate that tarnished plant bugs consume a significant quantity of E. kuehniella eggs per day and that this behaviour varies according to the availability of a plant resource. Additionally, the broad-sense heritability (H²) in zoophagy is significant, with an estimated 0.27. Moreover, highly zoophagous lines are less responsive to the availability of plant resources than lowly zoophagous lines. The results suggest that individuals within tarnished plant bug populations exhibit varying levels of prey consumption, which may indicate potential differences in trophic behaviour. However, the relationship between fitness and prey consumption in this phytozoophagous insect has yet to be established.