Sugar-Beet Root Aphid, Pemphigus betae Doane (Homoptera: Aphididae), in Southern Alberta

Abstract

In southern Alberta the fundatrix of P. betae hatches from the overwintered egg in late April and early May and feeds on an emerging leaf of P. angustifolia or P. balsamifera, forming a gall. In the gall it produces alate fundatrigeniae, which migrate from the poplars to beets and produce apterous alienicolae. This form of the aphid reduces both yield and sugar content of beet roots. During the summer several generations of alienicolae are produced. In the fall most of the alienicolae produce sexuparae. These migrate from beets to poplars, where they produce males and oviparae. Each fertilized ovipara lays a single egg on the bark of a poplar tree. The species may overwinter as eggs on the poplars or as alienicolae in the soil. The egg has an obligatory diapause that is terminated by exposure to low temperature. The fungatrigeniae migrate from late June to mid-August and the sexuparae from early September to late October. The potential reproductive capacities of the fundatrix, fundatrigenia, sexupara, and ovipara averaged 163, 13, 6, and 1, respectively. Under greenhouse conditions 20 aphids (alienicolae) produced 9,000 in 6 weeks when the soil temperature was maintained at 27 °C. Below 15 °C. the rate of reproduction was low and death was caused by exposure to 30 °C. for 6 weeks. The most important predators of P. betae were the anthocorid A. antevolens, the flies S. bigelowi, L. pemphigae and T. glabra, and a coccinellid Scymnus sp.