U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Commodity Protection and Quality Research: Parlier, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Research Units
                        San Joaquin Valley Agricultural Sciences Center
                                    Crop Diseases, Pests and Genetics Research
                                    Water Management Research
                                    National Arid Land Plant Genetic RepositorySearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Parlier, California San Joaquin Valley Agricultural Sciences Center Commodity Protection and Quality Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            DEMKOVICH, MARK - UNIVERSITY OF ILLINOISitem
                                            Siegel, Joelitem
                                            HIGBEE, BRADLEY - PARAMOUNT FARMING COMPANY, INC.item
                                            BERENBAUM, MAY - UNIVERSITY OF ILLINOIS
  Submitted to: Environmental Entomology
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 3/23/2015
                                    Publication  Date: 4/23/2015
                                    Citation: Demkovich, M., Siegel, J.P., Higbee, B.S., Berenbaum, M.R. 2015. Mechanism of resistance acquisition and potential associated fitness costs in navel orangeworm (Amyelois transitella) exposed to pyrethroid insecticides. Environmental Entomology. 44(3):855-863.Interpretive Summary: The navel orangeworm, Amyelois transitella, is the most destructive pest of almonds and pistachios grown in California. These two crops are planted on more than 1.1 million acres and have a direct value to the grower of more than $7 billion. Insect damage is controlled by a combination of methods including field sanitation and insecticide use when necessary. As the value of these crops has increased, so has insecticide use, and resistance to a widely used family of insecticides known as pyrethroids has been reported in Kern County. We established a colony from these resistant insects and used this colony to test the degree of resistance relative to a susceptible strain. Our assay method consisted of feeding studies on artificial diet, to which were added insecticides and other chemicals to test how the larvae detoxified the chemicals present in their diet. Our studies revealed that two classes of enzymes, cytochrome P450 monooxygenases (P450s) and carboxylesterases (COEs), contribute to resistance in this population. Resistance is primarily metabolic and is not caused by a change in the target site for pyrethroids. We also found differences in development time between the resistant and susceptible strains. We conclude that resistance is inherited and has a fitness cost because resistant larvae are smaller than their susceptible counterparts. This may influence their spread into regions where pyrethroid use is less frequent.
                                Technical Abstract: The polyphagous navel orangeworm (Amyelois transitella) is the most destructive pest of nut crops, including almonds and pistachios, in California orchards. Management of this insect has typically been a combination of cultural controls and insecticide use, with the latter increasing substantially along with the value of these commodities. Possibly associated with increased insecticide use, apparent insecticide resistance has been observed recently in navel orangeworm populations in Kern County, CA. In studies characterizing a putatively pyrethroid-resistant strain (R347) of navel orangeworm, susceptibility to bifenthrin and ß-cyfluthrin was compared to that of an established colony of susceptible navel orangeworm (CPQ). Administration of piperonyl butoxide and S,S,S-tributyl phosphorotrithioate (DEF) in first instar feeding bioassays with the pyrethroids bifenthrin and ß-cyfluthrin produced synergistic effects and demonstrated that cytochrome P450 monooxygenases (P450s) and carboxylesterases (COEs) contribute to resistance in this population. Resistance is therefore primarily metabolic and likely the result of overexpression of specific P450 and COE genes. Resistance was assessed by median-lethal concentration (LC50) assays and maintained across nine generations in the laboratory. Life history trait comparisons between the resistant strain and susceptible strain revealed significantly lower pupal weights in resistant individuals reared on the same wheat bran-based artificial diet across six generations. Time to second instar was greater in the resistant strain than the susceptible strain, although overall development time was not significantly different between strains. Resistance was heritable and may have an associated fitness cost, which could influence the dispersal and expansion of resistant populations in nut-growing areas in California.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov