Lygus bugs (Hemiptera: Miridae) are economically significant pests in Western Canada, threatening faba bean production through their piercing-sucking feeding mechanism. This feeding behavior causes mechanical and physiological damage to seeds, resulting in yield losses and quality downgrades that often fail to meet Grade No. 1 standards. The severity of damage depends on Lygus abundance, feeding duration, and host preferences, while environmental factors such as climate and geography influence infestation dynamics. This project integrates laboratory experiments, field studies, and statistical analyses to better understand Lygus feeding behavior and develop sustainable pest management strategies for faba bean growers.

Controlled experiments using no-choice bioassays and electrical penetration graph (EPG) technology established a quantitative link between Lygus feeding duration and seed damage. These findings provided foundational insights into the mechanisms of damage and informed subsequent experiments on host preferences. Choice bioassays identified safflower, sunflower, and canola as attractive crops for Lygus, suggesting their potential use as trap crops. Conversely, peas were the least preferred host. Behavioral differences between male and female Lygus were also noted: males showed a preference for faba beans, while females preferred canola. These results support the integration of trap crops as a sustainable approach to reducing pest pressure on faba beans.

Field studies conducted across Saskatchewan from 2019 to 2023 assessed the incidence and severity of Lygus infestations in faba bean fields. Using sweep net sampling at the R4 growth stage, we documented species composition and abundance in relation to environmental variables, including degree days (DD), total precipitation (TP), and soil zones. Statistical analyses revealed significant temporal and spatial variability in Lygus populations. Year and crop district (CD) together accounted for 40.74% of the variation in Lygus community composition, while species-specific responses to environmental factors were also noted. For example, L. lineolaris was negatively associated with DD and TP, while L. borealis was positively influenced by DD. These findings highlight the complexity of Lygus population dynamics and provide valuable insights for targeted pest management strategies.

The effectiveness of insecticides was evaluated in southern Alberta during 2022 and 2023. Matador consistently provided yield protection and improved seed quality by reducing necrotic damage, while Beleaf offered an alternative option for mitigating Lygus damage. However, field trials in central Alberta showed that while insecticide applications did not improve yield weight, they reduced the severity of necrotic damage caused by Lygus feeding.

Overall, this research demonstrates that effective management of Lygus bugs in faba bean production requires a multifaceted approach. Maintaining Lygus populations below a nominal threshold of 5–7 per 10 sweeps at the early pod stage is critical. Additional strategies include the integration of trap crops, targeted use of insecticides, and improved understanding of environmental influences on Lygus population dynamics. By combining laboratory findings with field observations, this project contributes to the development of sustainable and economically viable pest management strategies for faba bean production in Western Canada.

Key Outcomes include:

• Early intervention in Lygus management is critical to prevent feeding damage.
• Different life stages of Lygus show different feeding behaviors that influence seed damage.
• Matador and Beleaf insecticides were found to reduce necrotic seed damage effectively, with Matador consistently improving seed yield.
• Among the five plants used in the choice bioassays, alfalfa is a preferred host compared to faba bean