European populations of Diabrotica virgifera virgifera are resistant to aldrin, but not to methyl‐parathion

Abstract

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of cultivated corn in North America and has recently begun to invade Europe. In addition to crop rotation, chemical control is an important option for D. v. virgifera management. However, resistance to chemical insecticides has evolved repeatedly in the USA. In Europe, chemical control strategies have yet to be harmonized and no surveys of insecticide resistance have been carried out. We investigated the resistance to methyl‐parathion and aldrin of samples from nine D. v. virgifera field populations originating from two European outbreaks thought to have originated from two independent introductions from North America. Diagnostic concentration bioassays revealed that all nine D. v. virgifera field populations were resistant to aldrin but susceptible to methyl‐parathion. Aldrin resistance was probably introduced independently, at least twice, from North America into Europe, as there is no evident selection pressure to account for an increase of frequency of aldrin resistance in each of the invasive outbreaks in Europe. Our results suggest that organophosphates, such as methyl‐parathion, may still provide effective control of both larval and adult D. v. virgifera in the European invasive outbreaks studied.

Role of dispersal in resistance evolution and spread

“…This is surprising given that cyclodienes were withdrawn from use over a decade before the species reached the east coast and may represent an example of gene surfing [31]. Unlike populations in the United States, introduced European populations of D. v. virgifera are uniformly resistant to cyclodienes and susceptible to organophosphates [32]. Neither class of insecticide has been used extensively to control D. v. virgifera in Europe, so the current pattern of insecticide resistance there is probably a consequence of the North American populations that acted as the sources for introductions in Europe and bottlenecks during the introduction process [32].…”

“…Unlike populations in the United States, introduced European populations of D. v. virgifera are uniformly resistant to cyclodienes and susceptible to organophosphates [32]. Neither class of insecticide has been used extensively to control D. v. virgifera in Europe, so the current pattern of insecticide resistance there is probably a consequence of the North American populations that acted as the sources for introductions in Europe and bottlenecks during the introduction process [32]. The frequencies of an organophospate resistance allele in L. decemlineata show a surprising spatial distribution.…”

Estimating Diabrotica virgifera virgifera damage functions with field trial data: applying an unbalanced nested error component model

“…A major concern is that the western corn rootworm population in Europe will also develop resistance to control methods or that an introduction from North America has or will introduce resistance genes or the soybean variant into current European populations (Igrc Barcic et al. 2007; Ciosi et al. 2008b; Gray et al.…”

Global estimation of invasion risk zones for the western corn rootworm Diabrotica virgifera virgifera: integrating distribution models and physiological thresholds to assess climatic favourability

“…For this reason, the biology, physiology and ecology of the WCR have been the subject of study for decades in the USA (Krysan & Miller 1986), and are receiving increasing attention because of recent invasion events outside the USA (Miller et al. 2005; Vidal, Khulmann & Edwards 2005; Ciosi et al. 2009).…”