Ecological interactions between Lygus (Hemiptera: Miridae) and their nymphal parasitoids Peristenus (Hymenoptera: Braconidae) in southern Alberta

Abstract

Lygus bugs cause significant losses in commercial crops. Parasitoids (Peristenus) attack Lygus nymphs and have been considered to manage Lygus populations. The thesis provides information on the seasonal activity of three Peristenus species in southern Alberta, and a possible outcome of the European P. digoneutis in terms of Lygus control in canola, if present in the Prairies. Three native Peristenus species (P. braunae, P. carcamoi and P. broadbenti) occur sequentially during the season in southern Alberta. Overall parasitism did not exceed 16% during the season. In greenhouse trials, P. digoneutis parasitized Lygus nymphs on alfalfa and canola. Parasitism was on average up to 19% in alfalfa, and from 10-15% in canola. Nymphs’ mortality was higher in canola than alfalfa, and it increased with the presence of P. digoneutis. The potential of P. digoneutis to attack Lygus in canola can improve the latter’s management in the Prairies.