Rearing the oligophagous cactoblastis cactorum (Lepidoptera: Pyralidae) on meridic diets without host plant materials

Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), an oligophagous Opuntia spp. herbivore from South America, has been used successfully as a biological control agent for several invasive Opuntia species around the world. However, its unintentional arrival in Florida raised serious concern over its possible effect on native Opuntia biodiversity and Opuntia-based industries. Development of control tactics to mitigate the threat of this invasive pest to North America relied upon a constant supply of all life stages of this insect species. Therefore, 3 strains of C. cactorum were established in a laboratory insectary and trials were initiated to optimize rearing methods using an artificial diet. Because monophagous or oligophagous lepidopterans may be sensitive to the balance of nutrients and/or the presence of specific feeding cues and because different strains of an oligophagous lepidopteran may respond differently to various meridic diets, we compared the development and survival of 3 strains of C. cactorum on several meridic diets without host plant materials. Although C. cactorum is an oligophage within the genus Opuntia, it accepted and developed on several diets containing non-host plant ingredients, yeast, and fish meal. The source and balance of non-host nutrients significantly affected all reproductive parameters of C. cactorum. The best performance of C. cactorum was on diets that contained white kidney beans, brewer's yeast, wheat germ and/or soybeans.