Laboratory, Glasshouse, and Field Studies of Artificially Selected Carbaryl Resistance in Metaseiulus occidentalis12

Abstract

Laboratory and glasshouse tests were conducted to assess the vigor and reproductive compatibilities of two laboratory-selected carbaryl resistant strains of a predatory mite, Metaseiulus occidentalis (Nesbitt). Traits evaluated included development time, fecundity, sex ratio, mating compatibilities and competition, diapause, persistence of the carbaryl resistance characteristic, and the capability to control spider mite populations under carbaryl sprayed and unsprayed conditions. The resistant strains did not differ significantly from the susceptible strains tested in the absence of carbaryl treatment. The resistant strains were released in almond orchards where they survived arbaryl applications, controlled spider mite populations, and overwintered. This is believed to be the first time that the field effectiveness of a biological control agent has been improved through artificial selection.