Effects of spacing between rows on soybean arthropod populations.
Abstract
During the summer of 1976, population levels of various herbivores and all predators and parasites in fields in USA were monitored by three sampling methods (direct observation, sweep-net and vacuum net) on three different row-spacing plantings of soyabean, each planting treatment being replicated three times. Empoasca fabae (Harris) was most abundant in conventional row-spacing (96 cm) plots. Other herbivores were favoured in reduced row-spacing (high density) plots. All predators and parasites that showed significant differences among treatments reached highest population levels in the high density plantings. The reasons for the observed patterns are discussed.<new para>ADDITIONAL ABSTRACT:<new para>During summer 1976, population levels of various herbivores and all predators and parasitoids were monitored by 3 sampling methods (direct observation, sweepnet, vacuum net) on soyabean cv. Williams sown at between-row spacings of 24, 48 or 96 cm (high, medium and conventional low densities, resp.). The potato leafhopper Empoasca fabae was most abundant in conventional row-spacing plots. Other herbivores were favoured in reduced row-spacing (high density) plots. All predators and parasitoids which showed significant differences among treatments reached highest population levels in the high-density plots. Reasons for the observed patterns are discussed.