Article

Insecticides Suppress Natural Enemies and Increase Pest Damage in Cabbage

Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-75007 Uppsala, Sweden.
Journal of Economic Entomology (Impact Factor: 1.51). 06/2011; 104(3):782-91. DOI: 10.1603/EC10444
Source: PubMed

ABSTRACT

Intensive use of pesticides is common and increasing despite a growing and historically well documented awareness of the costs and hazards. The benefits from pesticides of increased yields from sufficient pest control may be outweighed by developed resistance in pests and killing of beneficial natural enemies. Other negative effects are human health problems and lower prices because of consumers' desire to buy organic products. Few studies have examined these trade-offs in the field. Here, we demonstrate that Nicaraguan cabbage (Brassica spp.) farmers may suffer economically by using insecticides as they get more damage by the main pest diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), at the same time as they spend economic resources on insecticides. Replicated similarly sized cabbage fields cultivated in a standardized manner were either treated with insecticides according common practice or not treated with insecticides over two seasons. Fields treated with insecticides suffered, compared with nontreated fields, equal or, at least in some periods of the seasons, higher diamondback moth pest attacks. These fields also had increased leaf damage on the harvested cabbage heads. Weight and size of the heads were not affected. The farmers received the same price on the local market irrespective of insecticide use. Rates of parasitized diamondback moth were consistently lower in the treated fields. Negative effects of using insecticides against diamondback moth were found for the density of parasitoids and generalist predatory wasps, and tended to affect spiders negatively. The observed increased leaf damages in insecticide-treated fields may be a combined consequence of insecticide resistance in the pest, and of lower predation and parasitization rates from naturally occurring predators that are suppressed by the insecticide applications. The results indicate biological control as a viable and economic alternative pest management strategy, something that may be particularly relevant for the production of cash crops in tropical countries where insecticide use is heavy and possibly increasing.

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Available from: Riccardo Bommarco, Sep 15, 2014
    • "However, they also indirectly affect crop yields by suppressing the positive effects of bird and insect activity. Pesticides are associated with declines in insectivorous birds (Hallmann et al. 2014), pollinators and natural enemies (Bommarco et al. 2011; Rundlöf et al. 2015), thereby suppressing beneficial animal activities that enhance marketable yields (Bommarco et al. 2011; Gillespie et al. 2014) and affecting ES in the long term (Chagnon et al. 2015). "
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    ABSTRACT: Ecological interactions between crops and wild animals frequently result in increases or declines in crop yield. Yet, positive and negative interactions have mostly been treated independently, owing partly to disciplinary silos in ecological and agricultural sciences. We advocate a new integrated research paradigm that explicitly recognizes cost-benefit trade-offs among animal activities and acknowledges that these activities occur within social-ecological contexts. Support for this paradigm is presented in an evidence-based conceptual model structured around five evidence statements highlighting emerging trends applicable to sustainable agriculture. The full range of benefits and costs associated with animal activities in agroecosystems cannot be quantified by focusing on single species groups, crops, or systems. Management of productive agroecosystems should sustain cycles of ecological interactions between crops and wild animals, not isolate these cycles from the system. Advancing this paradigm will therefore require integrated studies that determine net returns of animal activity in agroecosystems.
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    • "This also affects the functioning of natural pest control, as natural habitats provide shelter for a broad spectrum of natural species that operate as pest control for all crops (Thies and Tscharntke, 1999; Barbosa, 2003; Gurr et al., 2003, 2004; Altieri and Nicholls, 2004; Perfecto et al., 2004, 2009; Ponti et al., 2005; Bianchi et al., 2006; Macfadyen et al., 2009; Crowder et al., 2010; Rand et al., 2012). Research demonstrates that insecticides disrupt the communities of pest natural enemies, reducing the effectiveness of pest control and leading to increased pest damage in crops (Van den Bosch, 1989; Winston, 1997; Crowder et al., 2010; Bommarco et al., 2011). Hoy (1998) points out that effective resistance mitigation requires a holistic approach to pest management. "

    Full-text · Dataset · Aug 2015
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    • "This also affects the functioning of natural pest control, as natural habitats provide shelter for a broad spectrum of natural species that operate as pest control for all crops (Thies and Tscharntke, 1999; Barbosa, 2003; Gurr et al., 2003, 2004; Altieri and Nicholls, 2004; Perfecto et al., 2004, 2009; Ponti et al., 2005; Bianchi et al., 2006; Macfadyen et al., 2009; Crowder et al., 2010; Rand et al., 2012). Research demonstrates that insecticides disrupt the communities of pest natural enemies, reducing the effectiveness of pest control and leading to increased pest damage in crops (Van den Bosch, 1989; Winston, 1997; Crowder et al., 2010; Bommarco et al., 2011). Hoy (1998) points out that effective resistance mitigation requires a holistic approach to pest management. "

    Full-text · Dataset · Aug 2015
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