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Back to Non-Target Effects of Imidacloprid or Dr. Vera Krischik's Lab

Non-Target Effects of Imidacloprid: Lady Beetles

Effects of soil applications of imidacloprid on adult lady beetles

Imidacloprid is a systemic insecticide with soil, foliar and seed uses for control of sucking insects, including aphids, thrips, whiteflies and fungus gnats in the greenhouse. It is also used by botanical gardens, nurseries and golf courses to control white grubs feeding on roots, foliar feeding insects and borers that feed directly under tree bark. Imidacloprid is part of the neonicotinoids class of insecticides and acts upon the nervous system, causing blockage of postsynaptic acetylcholine receptors (Ware 2000).

The objective of this experiment was to investigate the effects of soil applications of imidacloprid (Marathon 1G) on nectar-feeding by four species of lady beetles: Coleomegilla maculata, Harmonia axyridis, Hippodamia convergens, and Coccinella septumpunctata. Beetles were allowed to chose between treated and untreated flowers to determine if they could detect and avoid imidacloprid in flower nectar.

Pink lady beetle (Coleomegilla maculata)
Jeff Hahn, University of Minnesota
  Asian lady beetle (Harmonia axyridis)
David Cappaert, Michigan State University
Convergent lady beetle (Hippodamia convergens)
Russ Ottens, University of Georgia
  7-spotted lady beetle (Coccinella septumpunctata)
Whitney Cranshaw, Colorado State University

Materials and Methods

Asclepias currissavica, Mexican milkweed, was untreated (C) or treated with imidacloprid (Marathon 1G) at label rate (1x) and twice label rate (2x). Each bioassay treatment contained 10 bioassay chambers each with 4-6 beetles. 3 replicate experiments were conducted.


Chamber treatments: C-C, 1x-C, 2x-C, 1x-1x, 2x-2x.

Residue analysis on flower nectar was performed at 21 d.

  buckwheat nectar milkweed nectar
  2004 June 2007 2 applications: Feb. & Sept. 2007
Control 0 ppb 2 ppb 0 ppb
1x 16 ppb 26 ppb 53 ppb
2x 29 ppb 61 ppb 110 ppb

Research shows that >20 ppb imidacloprid alters behavior of honey bees.

Results: Effects of imidacloprid on Coleomegilla, Harmonia, and Hippodamia



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Last modified on March 06, 2013