Conservation biological control in strawberry: effect of different pollen on development, survival, and reproduction of <i>Neoseiulus californicus</i> (Acari: Phytoseiidae)

Abstract

Wild vegetation surrounding crops may provide temporary habitat and potential food sources for phytoseiids in different seasons. Monthly vegetation samples of wild plants adjacent to strawberry plants and wild plants in a vegetation strip close to the crop were taken. The frequency of <i>Neoseiulus californicus</i>, <i>Tetranychus urticae</i> and other mites and insects was recorded. In addition, in a laboratory assay, the survival, developmental time and fecundity of females fed on pollen of strawberry and pollen of wild plants where <i>N. californicus</i> was recorded during their flowering, were estimated. Pollen from <i>Urtica urens</i>, <i>Lamium amplexicaule</i>, <i>Convolvulus arvensis</i>, <i>Sonchus oleraceous</i>, <i>Galega officinalis</i>, and <i>Fragaria</i> x <i>ananassa</i> (strawberry) allowed development of <i>N. californicus</i> to adult, but not reproduction. Survival was 70-80 % when fed on pollen from <i>S. oleraceus</i>, <i>G. officinalis</i> and <i>C. arvensis</i>, 80-90 % when fed on pollen from <i>U. urens</i> and <i>F.</i> x <i>ananassa</i>, and more than 90 % when fed on <i>T. urticae</i> and on pollen from <i>L. amplexicaule</i>. In autumn and winter, <i>U. urens</i>, <i>L. amplexicaule</i> and <i>S. oleraceous</i> could promote the persistence of <i>N. californicus</i> when prey density in strawberry is low, offering <i>T. urticae</i>, thrips and pollen. In summer, pollen of <i>C. arvensis</i> and <i>G. officinalis</i> would contribute to the persistence of <i>N. californicus</i> when the strawberry crop is ending and offers scarce food resources. Although the pollen of these plants would not enable the predator population to increase, the presence of these plants in the vicinity of strawberry could contribute to the persistence of <i>N. californicus</i> population and help to limit <i>T. urticae</i> growth when this pest begins to colonize the crop.