Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/9/2009
Publication Date: 4/1/2010
Citation: Lapointe, S.L., Evens, T.J., Niedz, R.P., Hall, D.G. 2010. Artificial diet optimized to produce normative adults of Diaprepes abbreviatus (Coleoptera: Curculionidae). Environmental Entomology. 39:670-677. Interpretive Summary: Many advancements in control of insect pests depend on our ability to rear them on artificial diets. Most diets consist of a mixture of multiple ingredients. In the past, most diets were developed empirically (by trial and error). Modern statistical methods are now available that are capable of greatly simplifying the process of diet optimization, thereby leading to improvements in the quality of artificially reared insects and to reductions in cost and complexity. We used a geometric multivariate design that allowed us to reduce the number of nutritive ingredients in an artificial diet for the tropical root weevil Diaprepes abbreviatus, a major pest of citrus. We also mathematically described adult weight as a function of the concentration of diet ingredients so that it is now possible to produce adult weevils of a given target weight. The current commercially-available artificial diet for D. abbreviatus produces adults 2 to 3 time as heavy as field-collected adults. We achieved our objective of producing weevils from an artificial diet that are equivalent in weight to adults collected from the field in Florida. Our on-going hypothesis is that artifically-reared insects of normative weight are similar in terms of behavior and therefore are better for use in research.
Technical Abstract: Insect diets are often complex mixtures of vitamins, salts, preservatives, and nutrients (carbohydrates, lipids and proteins). To determine the effect of varying the doses of multiple components, the traditional approach requires large factorial experiments resulting in very large numbers of treatment combinations and multiple interaction terms that are difficult to interpret. Geometric multivariate designs can greatly reduce the labor involved in optimization of diet blends. Field-collected adults of the tropical root weevil Diaprepes abbreviatus were on average, less than one-half the mass of adults reared on a commercially-available artificial diet. Progeny of lab-reared adults and field-collected adults reared on artificial diet were of similar size (elytron length) but progeny of field-collected adults reared on artificial diet attained greater mass compared with progeny of lab-reared adults. This indicates that the large size of lab-reared adults is not the result of adaptation to the artificial diet. We constructed a four-component design that included three principal drivers identified previously and added cellulose as a non-nutritive filler that could be scaled to produce adults of a desired mass. The dataset allows us to prescribe diet recipes to produce adults within a wide range of mass, including that of feral weevils.