A genetic analysis of mancozeb resistance in Typhlodromus pyri (Acari: Phytoseiidae).

A field population of Typhlodromus pyri (Acari: Phytoseiidae) tolerant to mancozeb was selected in the laboratory. After 10 mancozeb selections the LC50 value for mancozeb was 73 times higher in the selected-10 strain compared to the standard susceptible strain. A genetic analysis using reciprocal crosses and backcrosses of female F1 progeny found no maternal effect. Resistance in the selected-10 strain was codominant in expression, dominance value was about -0.1. Backcrosses between F1 females and the susceptible strain indicate that the resistance to mancozeb could be principally conferred by a predominant gene, but additional factors would also be involved.