Differences in within-plant oviposition preferences and immature survival between Orius predators and the importance of spatial availability of prey.

Oviposition preferences of plant-feeding predators remain a complex topic, as such omnivores choose oviposition sites by assessing both plant characteristics and the quality and quantity of nearby animal food sources. Orius predators are omnivores that oviposit endophytically, thus plant characteristics play an important role in their oviposition choices. In this study, we assessed the oviposition and foraging preferences of O. laevigatus and O. majusculus on vegetative and flowering chrysanthemum plants, and assessed the survival of their offspring on differently aged tissues. Our results show a preference of O. laevigatus for young and tender chrysanthemum tissues, where the survival of the nymphs was longer on a plant diet. In contrast, O. majusculus selected older plant parts when laying its eggs, and nymphs did not survive long on any of the plant tissues offered. The foraging activity of Orius females for animal prey (Ephestia kuehniella eggs) did not reveal any specific pattern for either of the two predators. Furthermore, we tested the plasticity of the within-plant oviposition preferences of O. laevigatus, by offering sentinel prey (E. kuehniella eggs) on distinct plant parts. We found that more eggs were laid in older plant tissue when animal prey was offered lower on the plant. Overall, our findings show that oviposition choices of Orius predators are based on a dynamic interplay between plant characteristics, presence of animal and/or floral food sources among other factors, and that differences may well occur between closely related species based on the importance of plant resources in their diet.