Oviposition Behaviour of Lygus rugulipennis and its Preferences for Plant Wounds

Little information is available on the oviposition behaviour and strategies of Lygus bugs, and these topics are unknown for most Miridae. Lygus rugulipennis, a widespread polyphagous species in the Palaearctic Region, is a serious pest of both herbaceous crops and fruit trees. Here we report on the L. rugulipennis oviposition behaviour and preferences. Experiments were carried out utilizing fresh green beans, and data were recorded using a computerized system for behavioural acquisitions. The L. rugulipennis female examines the plant substrate by means of the labial tip and then probes into the tissue using her stylets. Once the substrate is suitable, the female inserts her ovipositor precisely in the point previously probed and lays an egg. To investigate females’ oviposition preferences, their behaviour was compared on healthy green beans vs. artificially wounded green beans, with different types of wounds and at different time intervals (1 h, 6 h, 12 h, 24 h and 48 h) after wounding. Through labial and stylet examination, females distinguished healthy and wounded tissues and significantly preferred to oviposit in the latter, with different egg densities depending on the type of wound. Such preference changed at different time intervals after wounding. The lower resistance of the wounded substrate to ovipositor insertion, compared with the healthy substrate, was confirmed through a penetrometer test. Lygus preference for damaged tissues is discussed in terms of oviposition strategies in the insect-plant interaction context and strategies to escape natural enemies.