A new promising biocontrol agent Neoseiulus idaeus, in comparison with the phytoseiid’s star Phytoseiulus persimilis

Biological control of tetranychid mites on various agricultural crops is mainly conducted using phytoseiid mites. Specialised (type-I) phytoseiids are more effective in controlling phytophagous populations but generalist predators (type-II and III) can be more competitive in some field conditions. In the present work, biological, demographic and predation parameters of the native type-I Phytoseiulus persimilis and the alien type-II Neoseiulus idaeus, naturally coexisted in Sicilian crops, are compared in laboratory trials. Both phytoseiids showed the same short postembryonic development (≈4.5 days) and similar duration of the oviposition period (23.2 and 19.3 days for P. persimilis and N. idaeus respectively). However, the latter species showed a longer lifespan (50.9 days) but a lower reproduction activity (44.5 eggs/female) in comparison to the specialised P. persimilis (58.6 eggs/female). The demographic parameters of P. persimilis were better than those of N. idaeus but the latter species showed a good performance too. The predation ability of N. idaeus was higher during the postembryonic development but the situation inverted during the adulthood. Both unmated and mated females of P. persimilis preyed more Tetranychus urticae eggs than N. idaeus ones. However, the conversion index (eggs laid/preyed eggs) was higher in the latter species indicating it as more competitive at low T. urticae population densities. This study shows that N. idaeus has all the necessary characteristics to effectively control two-spotted spider populations.