Integrating pesticides and predatory mites in soft fruit crops

Abstract

Incorporation of predatory mites (Phytoseiidae) as biological control agents in soft fruit integrated pest management (IPM) programmes requires understanding of the interactions between environment, other organisms and crop management practices. This knowledge is dispersed among commercial online databases and peer reviewed papers and can be contradictory or difficult to access and interpret. The review brings together findings from databases and peer reviewed laboratory, field and semi-field studies of pesticide toxicity and persistence to soft fruit phytoseiid mites and also considers resistance, spray programmes and how these interact with species sensitivity, alternative food availability and plant structure. Predictably, acaricides and insecticides are the most toxic pesticides to phytoseiid mites, but their toxicity varies. Few fungicides are harmful, but data for many is lacking; it is very scarce for herbicides. There is virtually no data on tank mixes of pesticides applied to many soft fruit crops. Persistence of pesticides varies so release times for predatory mites after application range from a few days to several weeks and some of the most toxic active ingredients are not always the most persistent. Phytoseiid species vary in susceptibility to pesticides and in some populations resistance has occurred. Interactions with the environment are more difficult to define, but fungicides, for example, may reduce alternative food items whilst plant architecture may offer phytoseiid mites protection from spray residues. This review provides a timely synopsis to inform future research needs and provides practical guidance to enable better management of predatory mites in soft fruit crops.