|Morales Ramos, Juan|
Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 4, 1999
Publication Date: N/A
Interpretive Summary: Effective methods are needed to mass rear high quality beneficial insects that attack pest insects as an alternative to the use of environmentally hazardous pesticides. Diapetimorpha introita, a parasitoid that attacks pupae of the beet and fall armyworm, is a potential candidate for managing these pests, especially in area wide management programs. Scientists at the Center for Medical, Agricultural, and Veterinary Entomology, ARS, Gainesville, FL are developing an artificial diet for rearing the parasitoid, but improvements still are needed as developmental time, weight of adult wasps and fecundity were inferior compared to wasps reared on natural pupal hosts. They examined the potential of supplementing the artificial diet with insect cells produced in the laboratory to optimize the diet. Neither of the cell lines significantly improved the overall growth and development of the artificial diet, even after providing additional nutrients to the cell line-supplemented diets. These results suggest that future research should focus on isolating potential growth factors directly from the host pupa to improve the artificial diet for the parasitoid. Improving the diet will allow production of D. introita in numbers that can be used to augment other biorational measures for control of beet and fall armyworm.
Technical Abstract: Our objective was to investigate the use of an insect cell line to improve an artificial diet (DI diet) for the pupal ectoparasitoid Diapetimorpha introita (Cresson). When reared on the artificial diet, wasps were smaller, took longer to develop, and had reduced fecundity compared with wasps reared on the natural host. Two cell lines, IPL-LdFB, derived from fat body of the gypsy moth, Lymantria dispar (Linnaeus) and Sf9, derived from ovaries of the fall armyworm, Spodoptera frugiperda were used to condition Grace's culture medium for 24 h. The cell-conditioned medium from each cell line was then used to supplement the original DI diet. The diets were also chemically analyzed for nutrients and supplemented with additional nutrients where necessary. One-half ml aliquots of each diet were encapsulated in paraffin domes and newly hatched larvae of D. introita were placed on each diet (one larva/dome) and allowed to develop to the adult stage. Providing fresh diet on day four when the larvae were in the third instar did not improve parasitoid production. Compared with the DI diet, only the Sf9 cell line-supplemented diet (Sf9CellCond) had a positive effect on the parasitoid's growth and development, increasing the size of male parasitoids. Neither of the cell lines significantly enhanced the average weight of female parasitoids, shortened developmental time, or increased % cocoons produced and % adult emergence. However, providing additional nutrients (based on chemical analyses of the cell line- supplemented diets) to both diets also enhanced the average weight of the females on the Sf9CellCond diet and males and females on the IPL-CellCond diets but did not improve the other growth qualities measured.