The Development of the Clover Mite, Bryobia praetiosa (Acarina, Tetranychidae) in Relation to the Nitrogen, Phosphorus, and Potassium Nutrition of its Plant Host

Abstract

Mites were isolated on leaves of bush lima beans that were supplied, respectively, with three different concentrations of nitrogen, and four of phosphorus and of potassium, in nutrient solutions otherwise complete for plant growth; also, on leaves of plants supplied, respectively, with three different concentrations of the macronutrients of a complete nutrient solution. The nitrogen, phosphorus, and potassium content of the leaves was found to increase with increased supply of these elements. About six times as many mites developed on medium-nitrogen plants, and about 11 times as many on high-nitrogen plants, as on low-nitrogen plants. Larger mite populations developed with medium phosphorus or potassium supply than at lower or higher levels of these respective elements. Increase in nitrate-free nitrogen of the foliage was accompanied by increases in longevity of first-generation adults, duration of oviposition, number of eggs laid, and total number of adult second-generation mites (per parent mite) that reached maturity; and decreases occurred in duration of postembryonic development and total length of life cycle. Data are presented on various phases of the life cycle of 585 individuals observed under greenhouse conditions.