Investigation of imidacloprid resistance in blackmargined aphids (Monellia caryella)

Blackmargined aphid (BMA, Monellia caryella) is the primary arthropod pest in western pecan production. Imidacloprid, a nicotinic acetylcholine receptor (nAChR) agonist, has been the primary insecticide used to control BMA. During the past several years, reduced BMA control following foliar and soil applications of imidacloprid has been documented. Imidacloprid resistance in arthropods is linked to one or more mechanisms including genetic mutation in the nAChR subunits and enhanced detoxification due to increased production of the cytochrome P450 (CYP) gene. Research directed at investigating imidacloprid resistance mechanism(s) in BMA, and methodology to identify imidacloprid resistance in western BMA populations was initiated at New Mexico State University. Research progress is presented including a methodology to extract and clone BMA DNA. A sonication DNA extraction method was found to produce adequate amounts of BMA DNA, which was used to test 16 primer sets fabricated to match the nAChR sequence associated with brown planthopper resistance. Due to a number of unspecific PCR products, BMA DNA was cloned into plasmids and increased using Escherichia coli. Sequences did not match the nAChR gene due to the presence of multiple stop codons. The primers developed for this research were not successful in sequencing the specific BMA nAChR subunit. Additional primers were identified and used on the nAChR subunits and the CYP gene to successfully amplify BMA RNA. It is expected that results presented will consist of identifying the presence or absence of the mutation in the nAChR subunits, and quantification of the CYP gene.