Populations of Foliage‐Inhabiting Arthropods on Soybean with Reduced Tillage and Herbicide Use

Abstract

Modification of tillage and herbicide use patterns to reduce adverse environmental effects on soybean [Glycine max (L.) Merr.] production may impact arthropod populations and damage in soybean. The objectives of this field study were to examine the effect of reduced tillage and herbicide use on populations of foliage‐inhabiting phytophagous and beneficial arthropods and their damage in soybean. Tillage treatments of no‐tillage, chisel‐plow with disking, and moldboard plow with disking and herbicide regimes of high (preplant and postemergence control), reduced (postemergence control), and no herbicide use were established in a 2‐yr rotation of corn (Zea mays L.), winter wheat (Triticum aestivum L.), and soybean. Phytophagous and predatory arthropods were sampled from soybean foliage with the shake‐cloth technique throughout the season in 1988, 1990, and 1992. Tillage treatments did not consistently affect any arthropod groups except stink bugs (Pentatomidae), which were more abundant in no‐tillage than plow‐tillage treatments, and bigeyed bugs (Geocoris spp.), which were more abundant in both plow‐tillage treatments than in no‐tillage. Herbicide regime also had no consistent effect on abundance of any taxa. Additionally, tillage and herbicide regimes had little consistent effect on soybean lepidopteran defoliation and pod damage caused by the bean leaf beetle [Cerotoma trifurcata (Forster)] over the 3 yr. There were extensive stand losses due to rodent damage (cotton rat; Sigmodon hispidis Say & Ord) in the no‐tillage, no‐herbicide system in 1992, where crabgrass [Digitaria sanguinalis (L.) Scop.] was prevalent. These results suggest that tillage and herbicide use practices can be modified without greatly affecting arthropod populations and their damage in soybean. However, these results imply that the potential for managing arthropod populations by modified tillage and herbicide use is limited in soybean.

Effects of Weed Management Systems on Canopy Insects in Herbicide-Resistant Soybeans

“…This Þnding is in agreement with those by Buntin et al (1995) when they looked at tillage effects on bean leaf beetle. However, studies by House and Stinner (1983) showed higher numbers of beetles in less weedy plots, whereas Þndings by Troxclair and Boethel (1984) were mixed.…”

“…Furthermore, other insect species such as Mexican bean beetles, Epilachna varivestis Mulsant; velvetbean caterpillars, Anticarsia gemmatalis Hü bner; southern green stink bugs, Nezara viridula (L.); and corn earworms, Helicoverpa zea (Boddie) have been shown to be more abundant in weed-free soybean , Shelton and Edwards 1983, Alston et al 1991, Buntin et al 1995 than in soybean systems with weeds. Clearly, understanding changes in weed control in soybean will help in understanding changes to the insect populations within those systems as well.…”

Ocorrência de insetos na parte aérea da soja em função do manejo de plantas daninhas em cultivar convencional e geneticamente modificada resistente a glyphosate

“…Vários autores mencionam que o controle adequado de plantas daninhas pode afetar a abundância de artrópodes pragas (SHELTON & EDWARDS, 1983;BUNTIN et al, 1995;LAM & PEDIGO, 1998). SHELTON & EDWARDS (1983) verificaram que na soja livre de plantas daninhas ocorreu maior número de pragas e na presença destas plantas predominaram espécies predadoras.…”

Efeitos do plantio direto e da consorciação soja-milho sobre inimigos naturais e pragas

“…Tonhasca Junior (1993) também não observou diferença na ocorrência de predadores encontrados na parte aérea da soja sob plantio direto e convencional, enquanto Buntin et al (1995) constatou menor número de Geocoris spp. em plantio direto de soja.…”