Experience with the Diaprepes root weevil: implications for mass rearing the red palm weevil

Red palm weevil has become a major concern of date, coconut, oil and ornamental palm industries throughout the tropics and subtropics. Initiatives to control the weevil through sterile or genetically modified males will require methods for mass rearing. This could be the primary obstacle to implementation of innovative control strategies for this species. Typically, insect diets are complex mixtures of vitamins, salts, preservatives, and nutrients arrived at empirically. To determine the effect of varying the proportions 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. A commercially available diet blend has been used to rear the neotropical root weevil Diaprepes abbreviatus since the 1980s. With that diet as a starting point, we identified principal drivers, eliminated unnecessary ingredients and described a design space within which it is possible to arrive at diet recipes that produce adults of widely varying mass including that of feral weevils. Instead of a single diet, we derived a multidimensional space within which it is possible to navigate to achieve insects with the attributes desired by the researcher. Lessons learned may be applicable to optimization of an artificial diet for the red palm weevil.