2010 Annual Report
1a.Objectives (from AD-416)
To accelerate and enhance the formulation of high performance insect diets that improve the fitness of mass reared insects used in research and insects used in the biological control of insect and weed pests by: .
1)improving the formulation of artificial diets and diet-delivery systems;.
2)determining the impact of nutrient substitutions on the efficiency of diet utilization; and.
3)developing genomic biomarkers to monitor fitness traits related to nutrition.
1b.Approach (from AD-416)
Formulation changes will be made to micronutrient levels and substitutions will be made for the fibrous, temperature sensitive and antibiotic materials in artificial diets as part of an empirical-based effort to improve artificial diets. Life history measurements will be used to assess the impact those dietary changes on the health of the insect. The impact of dietary component changes on the biochemical fate of nutrients will be monitored. Enzymatic activity and metabolism of nutrients will be used to assess the impact of dietary changes on the efficiency of nutrient absorbance and nutrient utilization. The use of genomic biomarkers as indicators of fitness for insects reared on diets varying in nutritional quality will be investigated. Differentially-expressed genes will be identified using suppressive subtractive hybridization and microarray analyses.
This project was terminated on March 25, 2010 and replaced with 3622-22000-033-00D. We fully met and exceeded the intent of objective 1 which focused on biology of natural enemies in Component 2A. As originally designed, target insects of these efforts included both beneficial and pest insects; specifically predatory insects, insects used in sterile-insect-technology programs and new invasive insects that vector plant diseases. We substantially met the intent of objective 2, which was to determine the impact of nutrient substitutions on the efficiency of diet utilization. Knowledge of the biochemical fate of several dietary components has been significantly increased and that knowledge is being used by several research groups. We fully met and exceeded the intent of objective 3, which was to develop genomic biomarkers to monitor fitness traits related to nutrition. We documented the value of the technology, identified biomarkers and transferred the methods to other researchers.
Measuring the potential impact plant fortification may have on biological control. One of the current plant breeding strategies involves plant biofortification as a means of improving the dietary quality of plants consumed by livestock and humans. It is important to understand the effect plant biofortification will have on biological control efforts. Previous studies have shown that beneficial pathogens are less effective in controlling pest insects that feed on biofortified diets. ARS researchers in Columbia, Missouri demonstrated that beneficial parasites benefit from their host insect feeding on biofortified diets. In contrast, we found that beneficial predators may be negatively impacted by their host feeding on biofortified diets. Collectively these findings indicate there will be a shift in the effectiveness of biological control agents in cropping systems comprised of nutritionally enhanced plants. Both researchers and commercial groups will find this information to be of considerable importance as they test ways to enhance a wide variety of nutritional substances in plants and as they attempt to protect those plants from insect damage.
Developing biomarkers for accessing nutritional quality. The use of artificial diets as substitutes for natural food sources has been a major advancement in rearing insects. Unfortunately, it frequently has taken years to develop a functional artificial diet. Reducing the time requirement for diet formulation and testing may now be possible through nutrigenomics, based on determining the influence of nutrition on gene expression. By interpreting gene expression response to changes in specific components in the diet ARS researchers in Columbia, Missouri correlated the physiological effects caused by dietary changes to biochemical processes. As potentially practical tools, we identified several genes and gene products that may serve as biological indicators of healthy and harmful dietary components. Having these biological indicators will assist researchers and insectaries in the production of high quality insects which will improve the outcome of research and the performance of commercially produced insects.