The tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae) is a polyphagous pest that causes important economic damages in several crops including strawberry. This phytophagous insect feeds on more than 350 hosts, of which about 120 are economically relevant. Organic strawberry growers have few tools to fight the TPB, and so up to 100% of their yield can be lost due to this pest. The TPB is the main barrier that prevents transitioning from conventional to organic strawberry farming.
The TPB has several predators that can reduce its density in agroecosystems (e.g. predatory bugs, ladybeetles, spiders). However, these predators are not used in classical or inundative biological control because their potential is not yet determined. The role of predators as biological control agents of TPB has been overlooked for two reasons. First of all, the high reproduction rate of the TPB and secondly, the relatively low economic threshold may prevent a sole predator to effectively protect crops. In a recent study on the effect of trap crops on TPB in strawberry fields, we observed that both the damsel bug Nabis americoferus (Carayon) (Hemiptera: Nabidae) and the minute pirate bug Orius insidiosus (Say) (Hemiptera: Anthocoridae) naturally colonize plots exploited by the TPB and are suspected to be the main contributors to the TPB's mortality (about 50% from large nymphs to adults). The damsel bug feeds on every one of the TPB's developmental stages and has a life cycle that matches the TPB (besides having high fertility). The smaller but voracious pirate bug feeds on younger TPB stages and could be an adequate complement to the damsel bug. Both species are omnivorous and feed on several crop pests and pollen. Hence, these predators have interesting potential as biological control agents of the TPB. Moreover, both species oviposit on several plant hosts and could be relevant contributors to TPB mortality in various crops, including trap crops.
The aim of this project is to determine the potential of both N. americoferus and O. insidiosus bugs against the TPB and optimize their role in organic strawberry fields. An increase in these predators’ efficiency could be achieved through artificial selection on economically-relevant traits (e.g. predator consumption rate, diet specialization, host preferences etc.). Hence, this project includes a genetic improvement program (by artificial selection) in order to develop Nabis lines specifically efficient against the TPB (in a Nabis-Orius-Lygus system) and the compatibility of the predator with trap cropping and banker plant approaches. Once selected under laboratory conditions, that lines will be tested in organic strawberry fields. The optimal intervention threshold and predator release rate will be determined. The project should provide a new tool for organic strawberry growers to reduce TPB populations that will be compatible with others methods such as trap crops and the use of entomopathogenic fungi (e.g. Beauveria bassiana).
This project will propose a new pesticide alternative method that may be used under organic but also conventional production. Such new tools will reduce the use of synthetic/biological insecticides while also being effective in reducing TPB populations. Reduced application of insecticides has major impacts on the environment (soil, non-target organisms, water) and human health. Moreover, this IPM approach will be optimized in order to reduce costs and to increase economic outcomes, mainly by increasing productivity, reducing losses and by higher quality (and thus value) of organic fruits.
