Project Number: 6602-22000-035-03
Project Type: Reimbursable

Start Date: Jul 01, 2006
End Date: Sep 30, 2008

Objective:
Development of an efficient massrearing operation is critical to the successful mitigation of the invasive cactus moth, Cactoblastis cactorum. Initial trials in South Africa and in our USDA-ARS laboratory in Tifton, GA, demonstrated that C. cactorum could be reared on an artificial diet. However, low weight, low survival, and long developmental times indicated that improvements in the diet formula and presentation were needed. Subsequently, studies conducted in our laboratory demonstrated that wax-coated diet blocks and improved diet formulations could increase pupal weight and % survival, and could decrease the developmental time. Nevertheless, several challenges remain before efficient massrearing protocols can be established. For example, low fecundity results in a lower intrinsic rate of increase per generation and thereby increases the size of the brood colony required to produce the moths needed in the sterile insect technique releases. Observations have revealed that cactus moths that have developed in the laboratory on artificial diet are smaller, less fecund and have poorly developed fat bodies when compared with wild moths that developed in the field on live Opuntia. Therefore, to improve production in the massrearing of the cactus moth, we conclude that the artificial diet is lacking in appropriate feeding stimulants, sources of fat, and/or essential vitamins.

Approach:
Conduct a series of experiments to investigate the relationship between increasing concentrations of selected diet additives on developmental and reproductive parameters of the cactus moth. Diet additives will include sources of fatty acids, plant sugars, freeze-dried Opuntia cladode powder, vitamins and salts. Developmental and reproductive parameters will include developmental time, pupal weight, fat deposition, fecundity and fertility, mating propensity, and longevity. Experiments will be replicated 4-6 times. Regression analysis will be used for each ingredient to identify significant relationships and the optimum concentration. Additional experiments will be designed to examine the combination of ingredients that demonstrate significant positive effects.