Pesticides and phytoseiid mites: what the IOBC-WPRS Pesticide Side Effects Database can(not) tell us about selectivity?

Abstract: In the context of Integrated Pest Management (IPM), pesticide selectivity is defined
as compatibility of pesticides with natural enemies of phytophagous species as their biological
control agents. The choice of pesticides selective to Phytoseiidae, as the most significant natural enemies of phytophagous mites, implies the testing of effects of acaricides, as well as other pesticides (insecticides, fungicides, herbicides) with which the predators may come into
contact. The IOBC-WPRS Working Group “Pesticides and Beneficial Organisms” has
developed standard methods for over 30 beneficial species, tested over 200 pesticides and set
up a database of information gained by applying those methods. At the beginning of 2021, the
database comprised 1768 test results on the selectivity of 379 pesticides to 16 phytoseiid
species. Among acaricides, 98 compounds and 567 test results, neuroactive acaricides account for 70 % of the results, followed by those acting on growth and development (19 %) and respiration (11 %). Other tested pesticide compounds included 143 herbicides, 111 fungicides and 27 insecticides. The species Typhlodromus pyri stands out among phytoseiids (with 346 tested pesticides, 76 % of total results and 60 % of acaricide results), followed by Phytoseiulus persimilis, Amblyseius andersoni and Euseius finlandicus. Although widely adopted, the IOBC-WPRS sequential testing of selectivity has also been critically discussed. The key question is the accuracy of predictions drawn from the laboratory bioassays alone, which may be affected by various methodological and ecological factors. Besides, there is often a need to evaluate the compatibility of pesticides with predatory species/strains that are important in local environments. A complementary approach that integrates laboratory and field data, is needed as a sustainable solution to the evaluation of pesticide selectivity to phytoseiids.