Selection and genetic analysis of permethrin resistance in Amblyseius fallacis (Garman) (Acari: Phytoseiidae) from Ontario apple orchards

Abstract

Gravid female phytoseiid mites, Amblyseius fallacis (Garman), were selected for resistance to permethrin using a table-top Petri dish (PD) technique. After 55 selections, the LC50 of the R population increased 964-fold to 12 241 p.p.m. (PD) and 3.6-fold to 167 p.p.m. by a slide-dip (SD) method. A genetic analysis was conducted to examine the mode of inheritance by a series of single-pair reciprocal interstrain crosses and backcrosses of female F1 progeny. Concentration-mortality regressions (PD) for parental populations showed a 69.4-fold difference between R and S strains. Regressions for F1 females resulting from both interstrain crosses were intermediate between parental strains and not significantly different, showing no obvious maternal effect. Resistance in the R strain was not completely dominant or recessive and the estimated dominance, D, for the F1 females from combined data of both reciprocal crosses was-0.18, for the female R x male S cross it was 0.24 and for the female S x male R cross it was-0.01. We concluded that more than one gene was responsible for the resistance in the selected R strain. No incompatibility was observed in any reciprocal interstrain crosses or backcrosses between the S strain and R strain.