Larval Susceptibility of an Insecticide-Resistant Western Corn Rootworm (Coleoptera: Chrysomelidae) Population to Soil Insecticides: Laboratory Bioassays, Assays of Detoxification Enzymes, and Field Performance

Abstract Soil insecticides were evaluated in laboratory and field studies against larvae of an insecticide resistant population (Phelps County, NE) of western corn rootworm,Diabrotica virgifera virgiferaLeConte. Insecticide toxicity was evaluated by topical application of technical insecticides to 3rd instars from Saunders County, NE (susceptible) and Phelps County populations. Resistance ratios (LD50Phelps County/LD50Saunders County) for the insecticides methyl parathion, tefluthrin, carbofuran, terbufos, and chlorpyrifos were 28.0, 9.3, 8.7, 2.6 and 1.3, respectively. Biochemical investigation of suspected enzymatic resistance mechanisms in 3rd instars identified significant elevation of esterase activity (alpha and beta naphthyl acetate hydrolysis [3.8- and 3.9-fold]). Examination of 3rd instar esterases by native PAGE identified increased intensity of several isoenzymes in the resistant population. Assays of cytochrome P450 activity (4-CNMA demethylation and aldrin epoxidation) did not identify elevated activity in resistant 3rd instars. Granular soil insecticides were applied at planting to corn, Zea mays L., in replicated field trials in 1997 and 1998 at the same Phelps County site as the source of resistant rootworms for the laboratory studies. In 1997, planting time applications of Counter 20CR, Counter 15 G (terbufos), and Lorsban 15 G (chlorpyrifos) resulted in the lowest root injury ratings (1–6 Iowa scale); 2.50, 2.55, 2.65, respectively (untreated check root rating of 4.55). In 1998, all insecticides performed similarly against a lower rootworm density (untreated check root rating of 3.72). These studies suggest that resistance previously documented in adults also is present in 3rd instars, esterases are possibly involved as resistance mechanisms, and resistance to methyl parathion in adults is also evident in larvae, but does not confer cross-resistance in larvae to all organophosphate insecticides.

[1]  L. Chandler,et al.  Carbaryl Susceptibility, Diagnostic Concentration Determination, and Synergism for U.S. Populations of Western Corn Rootworm (Coleoptera: Chrysomelidae) , 1999 .

[2]  L. Chandler,et al.  Mechanisms of methyl and ethyl parathion resistance in the western corn rootworm (Coleoptera: Chrysomelidae) , 1998 .

[3]  L. Chandler,et al.  Adult Susceptibility of Nebraska Western Corn Rootworm (Coleoptera: Chrysomelidae) Populations to Selected Insecticides , 1998 .

[4]  K. Steffey,et al.  Corn Rootworm (Coleoptera: Chrysomelidae) Larval Injury and Root Compensation of 12 Maize Hybrids: an Assessment of the Economic Injury Index , 1998 .

[5]  J. Stuart,et al.  Behavioral and Feeding Assays Reveal a Western Corn Rootworm (Coleoptera: Chrysomelidae) Variant That Is Attracted to Soybean , 1997 .

[6]  Eli Levine,et al.  Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Injury to Corn Grown for Seed Production Following Soybeans Grown for Seed Production , 1996 .

[7]  M. Scharf,et al.  Comparisons of Three Insecticide Resistance Detection Methods for the German Cockroach (Dictyoptera: Blattellidae) , 1995 .

[8]  H. Preisler,et al.  Pesticide Bioassays With Arthropods , 1991 .

[9]  N. Elliott,et al.  Effect of Insecticides on Survival, Development, Fecundity, and Sex Ratio in Controlled Infestations of Western Corn Rootworm (Coleoptera: Chrysomelidae) , 1991 .

[10]  Z. Mayo,et al.  Influence of edaphological factors on residual activity of selected insecticides in laboratory studies with emphasis on soil moisture and temperature. , 1990 .

[11]  B. Siegfried,et al.  Properties of a cytochrome P-450-dependent epoxidase in aldrin-resistant western corn rootworms, Diabrotica virgifera virgifera LeConte , 1988 .

[12]  H. J. Ball,et al.  Bioassay Rating System for Predicting Mortality of Moribund Corn Rootworm (Coleoptera: Chrysomelidae) Larvae Following Exposure to Insecticide-treated Soil , 1985 .

[13]  G. R. Sutter Comparative Toxicity of Insecticides for Corn Rootworm (Coleoptera: Chrysomelidae) Larvae in a Soil Bioassay , 1982 .

[14]  R. Metcalf,et al.  Susceptibility of Four Species of Diabrotica to Insecticides , 1978 .

[15]  D. C. Peters,et al.  A method of evaluating postplanting insecticide treatments for control of western corn rootworm larvae. , 1971, Journal of economic entomology.

[16]  D. Kupfer,et al.  Determination of enzymic demethylation of p-chloro-N-methylaniline. Assay of aniline and p-chloroaniline. , 1966, Analytical biochemistry.

[17]  K. Asperen A study of housefly esterases by means of a sensitive colorimetric method , 1962 .

[18]  R. Wright,et al.  EVALUATION OF SOIL INSECTICIDES FOR CONTROL OF LARVAL CORN ROOTWORM, 2000B , 2001 .

[19]  R. Wright,et al.  Evaluation of Soil Insecticides for Control of Larval Corn Rootworm, 1997 , 1998 .

[20]  L. Meinke MP92-63 Adult Corn Rootworm Management , 1992 .

[21]  E. Levine,et al.  Management of Diabroticite Rootworms in Corn , 1991 .

[22]  Z. Mayo Field Evaluation of Insecticides for Control of Larvae of Corn Rootworms , 1986 .

[23]  J. Jackson Rearing and Handling of Diabrotica virgifera and Diabrotica undecimpunctata howardi , 1986 .