Influence of selected fruit tree pollen on life history of Euseius stipulatus (Acari: Phytoseiidae)

Euseius stipulatus (Athias-Henriot) is a predatory mite widespread in the Mediterranean region considered to be important for the biological control of spider mites in citrus orchards. Development, survival and reproduction of this phytoseiid mite feeding on seven commercially obtained pollen were studied under constant laboratory conditions (20 ± 1°C, RH 65 ± 5%, photoperiod 16L: 8D h). Mites were kept individually at rearing units with ample quantity of almond (Prunus amygdalus Batch), apple (Malus domestica Borkh), apricot (Prunus armeniaca L.), cherry (Prunus avium L.), pear (Pyrus communis L.), plum (Prunus domestica L.) and walnut (Juglans regia L.) pollen as food source. Developmental time from egg to adult varied between the several pollen tested from 8.38 ± 0.08 to 9.58 ± 0.11 days for females and from 8.23 ± 0.12 and 9.07 ± 0.12 days for males. Female longevity varied from 11.53 ± 1.22 to 51.38 ± 2.45 days, while fecundity ranged from 22.84 ± 2.30 to 43.61 ± 3.78 eggs/female. The predator was unable to reproduce when feeding on walnut pollen. Data were submitted to life table analysis and values of the intrinsic rate of increase were derived, ranging from 0.079 to 0.146 (day⁻¹). The cumulative Weibull function that was used to describe the age specific survival of females produced excellent fits to the survival data. Results show that almond, plum, cherry and apricot pollen possess higher nutritional value for E. stipulatus than pear and apple pollen and thus may contribute in sustaining and increasing the predator population in field conditions. Walnut pollen can be utilized by the predator only to survive during short periods of time when principal or alternative food sources are scarce.