Efficacy of Zeolite and Kaolin in the Control of <i>Cacopsylla pyri</i> (L.) (Hemiptera: Psyllidae) and Compatibility With Its Natural Antagonist <i>Anthocoris nemoralis</i> (Fabricius) (Hemiptera: Anthocoridae)

ABSTRACT The pear psyllid Cacopsylla pyri is a major pest of European pear orchards, responsible for significant yield losses. Its management is increasingly challenged by restrictions on synthetic active ingredients, resistance development, and the shift towards sustainable production systems. Therefore, in order to ensure the ecological and economic sustainability of pear cultivation, psyllid control requires innovative and selective approaches compatible with biological control agents, as the predator Anthocoris nemoralis . This study evaluated the efficacy of kaolin and zeolite, applied in both liquid and powder formulations, for the control of C. pyri and their compatibility towards the natural antagonist A. nemoralis . Laboratory assays, conducted under controlled conditions (24°C ± 2°C, 65% ± 5% RH, 16:8 L:D photoperiod), examined the effects on nymphs and eggs of the psyllid (acute mortality, ovicidal activity and oviposition deterrence) and potential side effects on the predator A. nemoralis , assessing acute mortality resulting from direct and indirect exposure to both particles. Results showed that powdered zeolite caused the highest mortality in nymphs, reaching approximately 48% at 10 days after treatment (DAT), compared with about 10% in the untreated control, whereas liquid zeolite exhibited the strongest ovicidal activity, with 21.2% of eggs remaining unhatched at 7 DAT, significantly higher than the control (3.8%). All treatments reduced oviposition compared to the control, indicating a deterrent effect: the mean number of eggs per plant decreased from 27.2 in the control to 3.7, 7.1 and 4.4 in ZEO‐L, ZEO‐P and KAO‐L treatments, respectively. Regarding A. nemoralis , powder applications (both kaolin and zeolite) caused higher mortality, while liquid formulations proved more selective and therefore more compatible with biological control (&lt; 15% at 6 DAT). Overall, kaolin showed lower efficacy than zeolite, although still yielding meaningful results. This study demonstrates that these geomaterials, particularly liquid zeolite, have significant potential as non‐toxic physical tools to be integrated into sustainable pear pest management programs. Future research should investigate the persistence and field performance of these materials under different environmental conditions and evaluate their optimal integration with other biological and integrated pest control strategies.