Behavioural study on host plants shared by the predator Dicyphus errans and the prey Tuta absoluta

In the Mediterranean basin, tomato has been attacked seriously by the exotic tomato borer, Tuta absoluta (Lepidoptera: Gelechiidae), reported also on other Solanaceae. Some generalist predators, belonging to the tribe Dicyphini (Hemiptera: Miridae), have demonstrated a good potential in controlling this pest. Among them, the Palaearctic Dicyphus errans occurs naturally in organic tomato in NW Italy, preys upon several pests and lives omnivorously on several plants. This predator seems to share various host plants with the tomato borer, characteristic that could be exploited by means of proper habitat modifications to enhance its predation during all the year. Therefore, host plant selection of both predator and prey was investigated in multi-choice assays with 10 plant species (aubergine, common bean, broad bean, courgette, datura, European black nightshade, herb-Robert, pepper, potato, tomato). Development and emergence rate of both predator and prey was assessed on tomato and European black nightshade, which is abundant in agro-ecosystems in NW Italy. Furthermore, behavioural responses of D. errans reared on tomato or European black nightshade were tested in olfactometer. Both predator and prey females oviposited on all tested plant species. However, significantly higher numbers of D. errans nymphs emerged on herb-Robert, whereas T. absoluta larvae were found almost exclusively on species of the genus Solanum. Despite the numerous eggs, no larvae could develop on courgette. No significant differences were found in developmental time on tomato and European black nightshade for both predator and prey. In olfactometer, D. errans did not show any significant preference between tomato and European black nightshade, independently of the rearing plant. In a perspective of conservation biological control, herb-Robert and courgette seem to be suitable plants to use as companion plants and in consociation with tomato to favour the predator and hamper the prey, respectively.