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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-BASED MANAGEMENT OF INSECT PESTS OF CORN, WITH EMPHASIS ON CORN BORERS, ROOTWORMS, AND CUTWORMS

Location: Corn Insects and Crop Genetics Research

Title: Development of a Tier-1 assay for assessing the toxicity of insecticidal substances against Coleomegilla maculata

Authors
item Li, Yunhe -
item Ostrem, Jared -
item Romeis, Jorg -
item Chen, Mao -
item Liu, Xiaoxia -
item Hellmich, Richard
item Shelton, Anthony -
item Peng, Yufa -

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 6, 2011
Publication Date: April 1, 2011
Citation: Li, Y., Ostrem, J., Romeis, J., Chen, M., Liu, X., Hellmich II, R.L., Shelton, A., Peng, Y. 2011. Development of a Tier-1 assay for assessing the toxicity of insecticidal substances against Coleomegilla maculata. Environmental Entomology. 40(2):496-502.

Interpretive Summary: A laboratory testing system was developed to assess the potential dietary effects of insecticidal substances on the predacious ladybird beetle, Coleomegilla maculata. Artificial diets utilizing shrimp eggs were developed, and a bioassay examining lady beetle development and survival was designed based on those diets. To further evaluate the artificial diet in a testing system, lady beetle larvae were fed the diet treated with different concentrations of an inorganic stomach poison, potassium arsenate, or a cysteine protease inhibitor, E-64. The results demonstrated that the testing system was capable of detecting the dietary effects of both substances on the survival and development of larvae. This study describes a robust testing system that will be useful for assessing the potential hazard (or toxicity) effects following dietary exposure of insecticidal compounds produced by genetically-engineered plants or conventional insecticides on this beetle. This information is useful to all scientists and regulators interested in evaluating the potential impact of genetically-engineered plants on non-target organisms.

Technical Abstract: A Tier-1 laboratory testing system was developed to assess the potential dietary effects of insecticidal substances on the predacious ladybird beetle, Coleomegilla maculata. Artificial diets utilizing shrimp eggs were developed, and a Tier-1 bioassay examining C. maculata development and survival was designed based on those diets. To further evaluate the artificial diet in a Tier-1 testing system, larvae of C. maculata were fed the diet treated with different concentrations of an inorganic stomach poison, potassium arsenate (PA), or a cysteine protease inhibitor, E-64. The results demonstrated that the testing system was capable of detecting the dietary effects of both substances on the survival and development of C. maculata. With increasing concentrations of potassium arsenate in the diet, fewer larvae developed to adults, with only 22.7% larvae surviving to the adult stage in the treatment with the highest content of PA (32 ug/g of diet). Likewise, dose-dependent responses were also found for other life-table parameters of C. maculata. Similar to the assays with potassium arsenate, the survival rates of C. maculata consistently decreased with increasing E-64 content in the diet. Survival analysis showed that the insects fed E-64 at 50, 150 and 450 ug/g in the diet had significantly lower survival rates compared to those on the untreated artificial diet. The study presented here describes a robust testing system that will be useful for assessing the potential hazard (or toxicity) effects following dietary exposure of insecticidal compounds produced by genetically-engineered (GE) plants or conventional insecticides on the ladybird predator, C. maculata.

Last Modified: 10/22/2014
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