Potential of Non-chemical Control Strategies for Reduction of Soil Insect Damage in Sweetpotato

Abstract

<jats:p>This 2-year study was conducted to determine if soil insect damage could be reduced in sweetpotato <jats:italic>[Ipomoea batatas</jats:italic> (L.) Lam] by treatment with an insecticide (fonofos) and/or a parasitic nematode <jats:italic>(Steinernema carpocapsae</jats:italic> Weiser), in conjunction with sweetpotato cultivars that differed in susceptibility to soil insect damage. Analysis of field data for the first year showed that the parasitic nematode provided significant damage protection of sweetpotato from wireworms <jats:italic>(Conoderus</jats:italic> spp.), Diabrotica sp., <jats:italic>Systena</jats:italic> sp., and sweetpotato flea beetle <jats:italic>(Chaetocnema confinis</jats:italic> Crotch), but not from grubs <jats:italic>(Plectris aliena</jats:italic> Chapin; <jats:italic>Phyllophaga ephilida</jats:italic> Say). In this same test, fonofos used alone provided protection against wireworm-<jats:italic>Diabrotica-Systena</jats:italic> (WDS complex) damage. In the second test, the nematode did not provide soil insect protection for the WDS complex, but fonofos did reduce damage for these insects. Poor efficacy in the second test with the nematode probably was due to high rainfall, which saturated the soil. Resistant cultivars provided good protection for all three categories of damage. When used with the insect-susceptible check `SC 1149-19', the nematode or fonofos treatments provided better control for all insect categories in the first test. In both years, much higher control of damage by all insect classes was achieved by the use of resistant cultivars in combination with the nematode and/or fonofos treatment (64% higher crop protection than the susceptible check line). Chemical name used: O-ethyl-S-phenylethylphosphonodithioate [fonofos (Dyfonate 10G)].</jats:p>

Improved Dry-Fleshed Sweetpotato Genotypes Resistant to Insect Pests

“…SC1149-19, which has been used frequently as a susceptible control in Þeld evaluations of sweetpotato germplasm Rolston et al 1979;Schalk et al 1986Schalk et al , 1993Jackson et al 2002Jackson et al , 2003, was the most susceptible genotype in our study. This cultivar had a signiÞcantly lower percentage of uninjured roots than all other sweetpotato entries in this study (Table 1).…”

“…In some instances, insecticides fail to provide adequate protection to roots, and yield losses due to insects can exceed 50%, especially in countries where low-input agricultural systems predominate (Lawrence et al 1997). Effective, low-input, environmentally benign integrated pest management (IPM) approaches are needed as alternatives to chemical pest control (Schalk et al 1993, Lawrence et al 1997.…”

Screening Spanish isolates of steinernematid nematodes for use as biological control agents through laboratory and greenhouse microcosm studies

“…Steinernema feltiae Rioja strain might be a useful isolate for the control of this insect even though it only caused 7% mortality in 2 days. Schalk et al (1993) observed that the combined use of resistant cultivars of S. tuberosum and/or insecticides together with S. carpocapsae reduced damage caused by wireworms. The study of synergisms with other natural enemies and/or agrochemicals together with this EPN strain might provide a new tool for the control of this pest.…”

“…The European and Mediterranean Plant Protection Organization consider S. littoralis and C. capitata as A2 quarantine pests, and recommend the development of novel control methods (OEPP/EPPO, 2006). Virulence studies of EPN strains against S. littoralis, C. capitata, and Agriotes spp are rare (Abdel-Razek, 2006;Gazit et al, 2000;Phan et al, 2005;Schalk et al, 1993). Therefore, our aim was to select and characterize the activity of the most promising native EPN strain to be developed as a biological control agent against these insects.…”

Control methods and monitoring of Agriotes wireworms (Coleoptera: Elateridae)

“…For instance, larvae of Limonius californicus (Toba et al 1983) or Conoderus spp. (Schalk et al 1993) were significantly reduced by Steinernema carpocapsae. Larvae of A. lineatus were reduced by Heterorhabditis bacteriophora (Ansari et al 2009), but not by Steinernema feltiae (Ester & Huiting 2007).…”