Effects of soil applications of imidacloprid on adult butterflies

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 adult painted lady butterflies (Vanessa cardui) and monarch butterflies (Danaus plexippus). A feeding test was set up in which adult butterflies in cages were fed nectary flowers from treated Asclepias curassavica, Mexican milkweed. Preliminary data on painted ladies and monarchs showed that imidacloprid had no effect on butterflies.
 

Painted lady (Vanessa cardui) William M. Ciesla, Forest Health Management International, www.insectimages.org		Monarch (Danaus plexippus) Charles T. Bryson, USDA Agricultural Research Service, www.insectimages.org

Materials and Methods
Butterflies were placed in cages with Asclepias currissavica, Mexican milkweed. The cages were cleaned and butterflies were provided with honey-water to supplement the nectar.

The experiment was examined in Asclepias currissavica, Mexican milkweed and annual buckwheat Fagopyrum esculentum. Neotropical Mexican milkweed is strongly recommended to use in conservatories, butterflies garden and nectar feeder (Missouri Department of Conservation 2005). Mexican milkweed has small, open flowers comprising an umbel on which lacewing adults can easily feed.

References
Missouri Department of Conservation. 2005. Butterfly Gardening and Conservation. http:/www.conservation.state.mo.us/nathis/insects/butterf/.

Ware, G. 2000. The Pesticides Book. Thomson Publications. Fresno, California