Long‐term effects of imidacloprid on the abundance of surface‐ and soil‐active nontarget fauna in turf

Abstract

1 Outbreaks of root-feeding scarab larvae in turfgrass are widely managed through preventive applications of imidacloprid. Long-residual activity and application before feasible scouting probably lead to its overuse and overexposure. 2 Recent investigations revealed a selective impact of imidacloprid (not trichlorfon or halofenozide) on certain nontarget turf arthropods, motivating the present study on the persistence of abundance effects over 6 years of annual applications. 3 Arthropods were sampled monthly (July to October) in replicated plots using soil core heat extraction and pitfall traps to quantify soil-and surface-active arthropods.Captures were identified to class, order or family. The most represented taxa were analysed to test for cumulative effects and their change over season and year. 4 Imidacloprid had no impact on pitfall captures, although the abundance of Hemiptera, Thysanoptera, Coleoptera and Collembola was suppressed in soil core captures. Among beetles, impact was expressed in adults (not larvae), and in Carabidae and Staphylinidae (not Chrysomelidae or Curculionidae). Among springtails, impact was expressed in Entomobryomorpha (not Poduromorpha or Symphypleona). Impact did not diminish with year but there was variable recovery between applications. 5 There may therefore be a diverging response of soil-and surface-active fauna to the nontarget impacts of imidacloprid. The suppression of predaceous (not phytophagous) beetles indicates an indirect effect mediated through declines in prey populations. 6 The magnitude of abundance effects confirms that the balance between target and nontarget impact should be explicitly examined. Implications are discussed with respect to functional relevance for nutrient cycling and the natural regulation of pests.

Effects of clothianidin‐treated seed on the arthropod community in a mid‐Atlantic no‐till corn agroecosystem

“…A germinated seed bioassay found that clothianidin seed treatments adversely affected 16 carabid species. Six years of annual imidacloprid soil‐applications in turf reduced adult staphylinid and carabid captures . Our results agree with the findings of these studies and also provide evidence of even higher reductions (20.2 and 34.5%) in predator abundance than the levels (∼16%) reported in the meta‐analysis study…”

“…Pooled together as a feeding guild, predators (primarily minute pirate bugs, ladybird beetles, lacewings, spiders, ground beetles, and rove beetles) in the epigeal and foliage communities were significantly less abundant in the insecticide treated plots by 20.2 and 34.5%, respectively. Other studies have reported similar negative effects on insect predators after exposure to neonicotinoid residues . The predator composition and abundance in imidacloprid seed treated and untreated corn fields over a 5‐year period showed adverse effects on Heteroptera, Staphylinidae, and to a lesser extent, Carabidae .…”

“…Studies have also demonstrated non‐target effects to bees (Hymenoptera: Apoidea) via exposure to contaminated dust during planting, guttation droplets exuded from treated corn seedlings, and residues in pollen and nectar . With only 1.6–20% of the active ingredient taken up by the plant, the persistence and environmental fate of neonicotinoid parent compounds and metabolites pose potential risks to soil invertebrates and microbial communities . Furthermore, detectable residues are increasingly present in surface waters due to their high water solubility and low soil binding, which can have negative impacts on aquatic systems …”

Rhizobacterial treatments of tall fescue and bermudagrass increases tolerance to damage from white grubs

“…Preventative control measures rely on the application of insecticides, often neonicotinoids, around the time of egg hatch but before white grubs are detected . Neonicotinoid insecticides applied for preventative control of white grubs have consequences for insect pollinators and beneficials, and soil‐dwelling invertebrates . These non‐target impacts of grub control create opportunities for alternatives such as increasing plant tolerance to damage.…”

Mapping Rm2 gene conferring resistance to the green peach aphid (Myzus persicae Sulzer) in the peach cultivar “Rubira®”

“…Thus, chemical control of the GPA population has little efficiency in the peach orchard management (Cravedi and Cervato 1997). In addition, the use of effective systemic insecticides such as imidacloprid has raised concerns in an increasing number of countries because of their possible non-targeted impact on beneficial insects (Decourtye et al 2004;Peck 2009). Natural enemies as biological control means or novel approaches such as kaolin treatments have been alternatively proposed (Barker et al 2007;Gentz et al 2010).…”