Level of Larval Atack on Maize Roots as a Consequence of Artificial Infestation With Western Corn Rootworm Eggs

Abstract

The Western corn rootworm (WCR), Diabrotica virgifera sp. virgifera(Col.,Chrysomelidae), is an oligophagous pest native in America. WCR is a maizepest present in all regions of the Corn Belt. It is an invasive species which was, inEurope, first identified in Serbia, in 1992, near the Belgrade airport. The presenceof this pest in maize field can cause losses and plant damages up to 100%. A fieldexperiment was carried out in Bečej, Vojvodina province (Serbia), during 2014 and2015. In the field, 96 plants (maize cultivar NS 640), arranged in 48 pairs wereselected. Each pair consisted of one plant artificially infested with WCR eggs (Dplant) and the control plant (C plant). In both years, the experiment in the field wasregularly inspected, once a week. During each observation, the presence of "gooseneck" symptoms was recorded, and the number of plants damaged by the mostimportant stem boring and leaf feeding insects (Ostrinia nubilalis, Helicoverpaarmigera, H. zeae, aphids, mites, cicadas, etc. ) was counted. Root damages wereassessed at the end of the experiment (September), according to Ostlie and Notzel(1987), on scale 1-6. Comparing the root damages on C and D plants, less rootdamages were established on C plants. Only six i. e. four D plants had healthy roots(rate 1) during 2014 and 2015, respectively. Between D plants in 2014, the mostdamaged were14 plants, with the rate 3 (least one root chewed to within 1½ inches(3. 8 cm) of the plant). In 2015, severe damages were registered on 18 plants,which were ranked as level 6 (with three or more nodes destroyed). Only two Cplants during vegetation 2014-2015were registered with damages with rate 5 (twonodes destroyed) and rate 6 (three or more nodes destroyed), respectively.

Volatile‐mediated oviposition preference for healthy over root‐infested plants by the European corn borer

“…ECB females were previously found to be able to distinguish between healthy plants and plants infested with conspecifics or with heterospecific leaf feeders through plant volatile emissions (Binder et al, 1995;Harmon et al, 2003). It is further consistent with the fact that WCRinfested plants suffered lower ECB infestation in the field (Tanaskovic et al, 2018). In our study, the distinction of healthy plants from rootinfested plants, was likely chemically-mediated, although possible visual cues cannot be fully excluded at this stage.…”

“…The two herbivores cooccur in nature, with WCR infestation preceding ECB oviposition (Meissle et al, 2011; Priesnitz et al, 2016). In the field, WCR‐damaged maize plants showed lower ECB infestation, although the underlying mechanisms could not be investigated (Tanaskovic et al, 2018).…”