Research Objective
To establish correlations between insect number and scarring damage for various Lygus species.
Objective 4To determine whether lygus populations in canola just before harvest are correlated to numbers in faba.
To gain knowledge of damage thresholds for Lygus in faba; to gain knowledge of the amount of Lygus feeding (time) required to cause pod damage in faba bean; to gain knowledge of the relationships between Lygus populations in canola and faba; to gain knowledge of optimal sampling times and new techniques for sampling Lygus in faba; to gain knowledge of Lygus preferences between faba and other crops.
Insects in the genus Lygus are true bugs belonging to the order Hemiptera and the family Miridae (Menardet et. al., 2013). The genus Lygus is one of the most economically important as it contains many species of insect pests (Wheeler, 2001). In Western Canada, adult Lygus typically migrate into crops in spring and summer from overwintering locations. Once in crops, they reproduce often with two generations per year. Overwintering usually occurs as adults under plant debris adjacent to fields. (George et.al., 2021). Lygus feed using piercing-sucking mouth parts that repeatedly penetrate the plant tissue causing mechanical damage via the injection of salivary enzymes into the plant tissue (Williams et.al., 2005). In faba bean (Vicia faba), this damage results in both reduced yield and quality downgrades. Faba for human consumption must be at Grade No. 1, and the upper limit is <4% of seeds damaged according to the Canadian export standards, including damage due to seed perforation (1%), and zero tolerance for rotted seeds (Government of Canada, 2023). These downgrades can reduce prices of faba as much as $2/bushel, resulting in substantial economic impact. This project focuses on four main objectives: evaluating Lygus damage in faba bean, determining Lygus preferences, and identifying or quantifying the incidence and severity of Lygus infestations in the fields. To achieve these goals, a combination of laboratory assays and field collections will be employed. As of this report, one field season has been completed and laboratory bioassays are in progress.