Populations of two-spotted spider mite (Tetranychus urticae) and soybean aphid (Aphis glycines) increase with soil salinity

Abiotic factors, like soil health are important to entomological study systems. Soil salinity is a major factor that determines soil health and soil function. It also affects plant health and may affect herbivorous arthropods. This study is a continuation of research investigating the effects of varying soil salinity on crop pests. We grew corn and soybean plants in the greenhouse in soil that was manipulated to vary in salinity (0.3-8 EC 1:1). We used the same experimental methodology to test three pest/host interactions. Plants that were grown in differing saline conditions, ranging from an electrical conductivity value of zero to eight, were infested with seven adult female arthropods, either two-spotted spider mites or soybean aphids, respectively. These arthropods were left on the plant for seven days, after which population numbers were quantified. In experiment #1 two-spotted spider mites were added to soybean plants. In experiment #2 two-spotted spider mites were added to corn plants. In experiment #3 soybean aphids were added to soybean plants. Our results indicate that for each of the three experiments the arthropods; two-spotted spider mite and soybean aphid responded positively to plants grown in relatively higher saline conditions. Population sizes in each of the three experiments were greater on plants grown in soils with relatively higher salinity compared to plants grown in less saline soils. Our research is important to growers, because saline soils may lead to a potential increase in pest pressure. This could add extra motivation for them to actively manage saline issues.