Circadian activity of Lygus lineolaris (Hemiptera : Miridae) and effectiveness of sampling techniques in strawberry fields

Mobility and distribution of adult tarnished plant Lug, Lygus lineolaris (P alisot de Beauvois), was studied on a day-neutral strawberry cultivar ('Sel va') in 1991 and 1992 at L'Acadie, Quebec, Canada. On cage-covered plants, individuals were located mainly on reproductive parts Study of the flight a ctivity with sticky posts revealed that most captures were obtained <1 m fr om ground level and that the time of the day at which the maximum counts oc cur varied among seasons. Three pest-sampling methods (white sticky trap, t apping of flower clusters, and D-Vac) were evaluated over continuous 24-h p eriods, Maximum captures of adults with white sticky traps were made at mid day (1000-1400 hours), whereas the two other methods proved more effective at the beginning (0600-0800 hours) or the end of the day (2000-2200 hours) or during night time. For nymphs, maximum catches were obtained during the day with tapping and D-Vac; white stick, traps were ineffective. Because th e D-Vac captures individuals present on all parts of the plant, these count s were used to monitor the effectiveness of the two other sampling techniqu es. The data suggest that tapping newer clusters throughout the day is a ve ry effective sampling method to estimate nymphal tarnished plant bug popula tions in strawberries. However, sampling of populations with a high proport ion of adults should take into account the bias caused by their flight acti vity, and sampling should be conducted early in the morning or at the end o f the day.