Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/1999
Publication Date: N/A
Interpretive Summary: One requirement delaying the increased use of beneficial organisms, such as parasites, predators, or microorganisms, to control pest insects and invasive plants is the limited technology available to produce large numbers of high quality beneficial organisms. The development of artificial diets to feed the beneficial organisms will aid in their mass production. However, poor reproductive capacity of artificially-reared beneficial organisms is common and adds to the expense of their production. A better understanding of the impact of artificial diets on the reproductive capacity of a beneficial organism is essential to the development of an economical and effective method for their production. The spined soldier bug (a beneficial insect predator) was studied to observe its ability to produce viable offspring when reared on natural prey and on an artificial diet. Also, a microscopic measurement method was used to evaluate the maturation rate of the ovaries in these predators. Result showed that the artificial diet slows down ovarian maturation and markedly reduces the ability to produce viable offspring in females. These findings define a method to measure the impact of artificial diets on the reproductive capacity, and provide some of the tools needed to determine the physiological level at which reproduction breaks down in artificial diet-fed insects. Development of highly efficient artificial diets for insect rearing will advance the cost-effective mass production of beneficial insects. That in turn should make beneficial insects more readily available, and will hopefully result in the reduction of crop damage, decrease in insecticide usage, and overcome insecticide resistance problems, thereby benefitting both the grower and the environment.
Technical Abstract: The fecundity and ovarian maturation rate of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) was examined under various feeding regimes. The effect of a meat-based artificial diet on the reproductive development of the females was determined, including the ability of their reproductive capacity to be recovered by feeding at the adult stage on natural prey larvae. A quantitative scoring method is utilized to evaluate the maturation rate of the ovaries in prey-fed, diet-fed, recovered and switched adult females. Results showed that the artificial diet slows down ovarian maturation and markedly reduces fecundity. Adult weights and oviposition rates were lower in insects fed artificial diet from early nymphal stage to adult. Partial improvement of ovarian maturation rates and fecundity was obtained when artificial diet-fed individuals were given prey as adults (recovered). Feeding the artificial diet to adults which were reared as nymphs on prey (switched) reduced both ovarian maturation rate and fecundity to levels significantly lower than continuously prey-fed females. Diet-fed (as nymphs and adults) males did not interfere with the reproductive capacity and fecundity of prey-fed females. Likewise, prey-fed males did not improve the low fecundity of diet-fed females.