The Use of Insecticides to Manage the Western Corn Rootworm, Diabrotica virgifera virgifera, LeConte: History, Field-Evolved Resistance, and Associated Mechanisms

Abstract

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Dvv) is a significant insect pest of maize in the United States (U.S.). This paper reviews the history of insecticide use in Dvv management programs, Dvv adaptation to insecticides, i.e., field-evolved resistance and associated mechanisms of resistance, plus the current role of insecticides in the transgenic era. In the western U.S. Corn Belt where continuous maize is commonly grown in large irrigated monocultures, broadcast-applied soil or foliar insecticides have been extensively used over time to manage annual densities of Dvv and other secondary insect pests. This has contributed to the sequential occurrence of Dvv resistance evolution to cyclodiene, organophosphate, carbamate, and pyrethroid insecticides since the 1950s. Mechanisms of resistance are complex, but both oxidative and hydrolytic metabolism contribute to organophosphate, carbamate, and pyrethroid resistance facilitating cross-resistance between insecticide classes. History shows that Dvv insecticide resistance can evolve quickly and may persist in field populations even in the absence of selection. This suggests minimal fitness costs associated with Dvv resistance. In the transgenic era, insecticides function primarily as complementary tools with other Dvv management tactics to manage annual Dvv densities/crop injury and resistance over time.

Experimental evolution of insect resistance to two pesticide classes reveals mechanistic diversity and context-dependent fitness costs

“…In addition to physiological modifications, metabolic detoxification may contribute to patterns of cross-or multiple resistance in disease vector and insect pests (Carletto et al, 2010;Carvalho et al, 2013;Edi et al, 2014;Yunta et al, 2019). Oxidative or hydrolytic processes often underlie cross-resistance patterns observed in insects (Basit, 2019;Meinke et al, 2021), and common differential expression of esterases, GSTs, and P450s is often observed between organophosphate and pyrethroid resistant populations (Carletto et al, 2010;Carvalho et al, 2013;Edi et al, 2014;Julio et al, 2017;Yunta et al, 2019). Here, pesticide selected populations varied in the genes commonly differentially expressed with pesticide regime and exposure indicating variation in the possibility for cross-resistance in populations.…”

“…Previous studies have highlighted the importance of P450s, esterases, GSTs, and other canonical detoxification genes underlying pyrethroid resistance (Boyer et al, 2012;David et al, 2014;Meinke et al, 2021;Zimmer et al, 2017). Indeed, we found that Pyr-regime populations commonly downregulated several canonical detoxification genes including five P450s, two GSTs, and two UGTs (Figs.…”

“…Based on previous studies investigating molecular mechanisms of organophosphate resistance, we expected common differential expression of detoxification genes including cytochrome P450s, carboxyl ester hydrolases (CEHs), esterases, and glutathione S-transferases (GSTs) among OP-regime populations (Boyer et al, 2012;Meinke et al, 2021;Oakeshott et al, 2013;Pavlidi et al, 2018;Sogorb and Vilanova, 2002;Tandonnet et al, 2020). However, after organophosphate selection, each population tended to differentially express different P450, GST, and UGT genes canonically associated with detoxification (Figs.…”

“…Target site mutations are rarely the whole story, however, as changes to the expression of existing genes also play a substantial role in resistance evolution. Organophosphates and pyrethroids are mainly detoxified through oxidation and hydrolysis, and resistance associated with differential expression of diverse canonical detoxification genes has been described for both pesticide types (Boyer et al, 2012;Meinke et al, 2021;Oakeshott et al, 2013;Pavlidi et al, 2018;Sogorb and Vilanova, 2002). Increased resistance to penetration through changes in cuticle and serine endopeptidase gene expression have also been implicated in organophosphate and pyrethroid resistance (David et al, 2014;Lilly et al, 2016;Tandonnet et al, 2020;Zimmer et al, 2017).…”

RNAi for Western Corn Rootworm Management: Lessons Learned, Challenges, and Future Directions

“…Native to Central America and first identified as a pest of cultivated maize in Colorado in 1909 [3,4], populations are now found throughout the midwestern U.S. and Europe [5,6]. Once achieving pest status, various control tactics have been used to reduce damage caused by WCR larval feeding including crop rotation, soil-applied insecticides, and maize hybrids expressing insecticidal proteins from the soil bacterium Bacillus thuringiensis Berliner (Bt) [2,7,8]. However, managing WCR has been historically challenging due to its remarkable ability to evolve resistance to all available management tactics throughout various local areas in the U.S. Corn Belt [2,7,[9][10][11][12][13][14].…”