Does feeding behavior of a zoophytophagous mirid differ between host plant and insect prey items?

Many mirid bugs are omnivores, and several species are key pests of agricultural crops. While mirid feeding behavior on plant hosts is relatively well studied, little attention has been paid to foraging, acceptance, and consumption of insect prey items. In this study, we investigated the feeding behavior and stylet penetration of the green mirid bug Apolygus lucorum on insect prey (Helicoverpa armigera eggs), plant hosts (green bean Phaseolus vulgaris pod), and combined plant + prey diets. Direct observation and electrical penetration graph (EPG) assays were used to assess feeding on either food item. Overall feeding time was highest on combined diets (48.18 ± 4.92 % of total time) and plant foods (42.23 ± 3.36 %), compared with only 28.95 ± 2.27 % feeding time on H. armigera eggs. When exposed to combined diets, A. lucorum spent 3.8 times longer feeding on green bean pod than on H. armigera eggs. The overall duration of stylet penetration was 5866.27 ± 800.39 s on green bean pod versus 3644.81 ± 715.19 s on H. armigera eggs, representing a 37.87 % reduction in duration. Similarly, the duration of a single probing event was significantly higher on green bean pod (355.76 ± 50.13 s) versus H. armigera eggs (236.20 ± 25.17 s), with a 33.61 % reduction. This first work in which omnivory is studied by combined use of observational studies and EPG assays (1) provides further insights into A. lucorum omnivory, (2) further elucidates its trophic position in agroecosystems, and (3) guides the development of artificial diets for this pest species.