Population development of the green peach aphid and beneficial insects in potato fields in British Columbia

Abstract

Using 4 years of potato monitoring data containing insect counts, population development of the green peach aphid (Myzus persicae (Sulzer)) (Hemiptera: Aphididae), ladybird beetles (Harmonia axyridis (Pallas) and Coccinella septempunctata L.) (Coleoptera: Coccinellidae), and hymenopterous aphid parasitoids is described and used to consider revisions to current sampling plans. Depending on the year, field monitoring for aphids commenced between early May and early June. Aphid populations typically increased after 1 July and fluctuated until the end of the monitoring period (September). Winged M. persicae began to appear in sweep-net samples in late May, well in advance of the detection of aphids in visual samples. Aphid counts from field edge and interior sample sites were correlated and edge population levels were slightly and significantly greater than interior levels over the period 10 June – 14 July in 2 of the 4 years analyzed, suggesting a mild but inconsistent edge effect approaching mid season. Using an action threshold of 1 aphid/leaf to restrict the aphid-mediated spread of potato leaf roll virus (PLRV), the earliest whole-field action threshold was exceeded during 18–24 June in 1997. Using an action threshold of 10 aphids/leaf to address aphid-induced yield loss in fields not at risk to PLRV, the earliest whole-field action threshold was exceeded during 16–22 July in 1997. Therefore, monitoring for aphids can begin much later than the time it is currently commenced. A case is presented for monitoring only the edges of potato fields for an action threshold of 10 aphids/leaf, as interior samples rarely exceeded this action threshold when edge samples were below. This would further reduce the effort in sampling potato fields for aphids. Population development of ladybird beetle adults and larvae showed peaks occurring at different times during the growing season, depending on the year. Parasitism of aphids by hymenopterans occurred at low to moderate levels throughout the growing season (13% of total aphids in visual samples, on average), with peak parasitism appearing toward the end of the growing season in each year.

Resistance of WildSolanumAccessions to Aphids and Other Potato Pests in Quebec Field Conditions

“…For both S. tarijense and S. polyadenium , the difference in pest density was mainly conferred by the plant resistance characteristics since natural enemies' density was very low. This low density is not surprising as previous studies demonstrated that the density of most natural enemies in potato fields closely follows that of M. persicae and M. euphorbiae ( Karley et al 2003 ; Kabaluk et al 2006 ). The relative capacity of pests and natural enemies to adapt and become able to exploit resources on resistant plant should be evaluated: should the pest adapt more rapidly, resistant plant would become an enemy-free space plant on which pests could thrive ( Gassmann and Hare 2005 ).…”

Differential sensitivity of an invasive and an indigenous ladybeetle to two reduced‐risk insecticides

“…), and greatly contributes to aphid control (Kabaluk et al. ). Coragen mc , containing chlorantraniliprole as the active ingredient, is approved to control the European corn borer, Ostrinia nubilalis (Hübner) (Lep., Crambidae), and other pests in maize (DuPont, ), where H. axyridis and C. maculata have been recorded as the two most abundant coccinellids (Lucas et al.…”

Toward management guidelines for soybean aphid, Aphis glycines, in Quebec. II. Spatial distribution of aphid populations in commercial soybean fields

“…Edge effects have been documented in some species of aphids, with plants near the edge of fields supporting a higher population density than plants in the interior of fields (Schotzko and Quisenberry 1999;Winder et al 1999;Jones 2005), although in some cases the effect is relatively small and inconsistent from year to year (Kabaluk et al 2006). For A. glycines, however, migrant adults do not seem to preferentially colonize plants near the edge of soybean fields (Hodgson et al 2005), and population density on a given plant seems to be independent of the distance between the plant and the edge of the field (Onstad et al 2005).…”